Derm

Question 1

4 causes of pseudoepitheliomatous hyperplasia?

Answer 1

Prurigo nodularis, some deep fungal infections (including Blastomycosis), granular cell tumors, halogenodermas (iododerma, bromoderma).

Question 2

Carney Complex. AKA (3)?

Answer 2

AKA LAMB syndrome (Lentigenes, Atrial myxomas, Mucocutaneous myxomas, Blue nevi), NAME syndrome (Nevi, Atrial myxomas, Myxoid neurofibroma, Ephelides), or Swiss syndrome. AD condition. The majority (Carney Complex type I) are caused by mutations in the PRKAR1-alpha gene on 17q24, which has been suggested to function as a tumor-suppressor gene. Carney Complex type II involves chromosome 2. 7% of all cardiac myxomas are associated with Carney complex. M=F. Mean age at Dx: 10-20 years.

Question 3

DDx of Merkel cell carcinoma.

Answer 3

The histologic features of MCC are similar to those of various other tumors, such as metastatic small cell carcinoma, the small round cell tumors, blastic hematologic malignancies of skin/soft tissue, and melanoma. Immunostains can help distinguish them.

Question 4

Examples of pseudoneoplastic lesions in the skin and their related neoplastic mimes.

Answer 4

Adnexal nevi [adnexal neoplasms]. Lymphoid hyperplasias [lymphomas]. Reactions to Monsel solution [sarcomas; sarcomatoid carcinomas]. Acroangiodermatitis AKA acroangiodermatitis of Mali AKA dermatitis hemostatica AKA Bluefarb-Stewart syndrome AKA pseudo-Kaposi sarcoma [Kaposi sarcoma]. Proliferating scars and posttraumatic spindle cell nodules [sarcomas; sarcomatoid carcinomas]. Intravascular papillary endothelial hyperplasia (Masson lesion) [angiosarcoma]. Pseudocarcinomatous (pseodoepitheliomatous) epithelial (epidermal) hyperplasia [squamous cell carcinoma]. Rudimentary meningocele [angiosarcoma]. Mycobacterial pseudotumors [mesenchymal neoplasms]. Bacillary angiomatosis [hemangiomas]. Other pseodoneoplasms include Der Wulst AKA central facial folliculocentric basaloid proliferation AKA hair follicle “bulges”, pseudosarcomatous fibroepithelial polyps (acrochordons), proliferative noninfectious granulomatous lesions, reactive angioendotheliomatosis, and intravascular histiocytopathy.

Question 5

Grover disease.

Answer 5

AKA Transient Acantholytic Dermatosis. Is a self-limited, primary, nonfamilial, non-immune-mediated acantholytic skin disorder that manifests are pruritic, discrete, edematous papules and/or a vesiculopapular rash. The term TAD may be misleading, since this entity may be persistent, recurrent and show morphologies other than acantholysis. M:F = 2.4:1. The lesions are mostly on the trunk (99%) and proximal extremities (35%). Grover disease has been found to coexist with numerous other dermatoses in 11% of cases, hematologic malignancies in 8% of cases, and has also been associated with skin cancers. Histologically, the acantholysis seen in Grover disease occurs in a variety of different patterns in small, circumscribed foci, with the patterns occuring singly, or pathognomonically in combination. Patterns of acantholysis seen in Grover disease: pemphigus vulgaris-like (47%), Darier-like (18%), spongiotic (9%), pemphigus foliaceous-like (9%), mixed (9%), and Hailey-Hailey-like (8%). Pathogenesis is unknown, but a strong relationship with heat, sunlight, exercise, and bed confinement places the eccrine apparatus as a primary suspect.

Question 6

Immunostains in melanocytic neoplasms in dermatopathology: S100, HMB-45, Melan-A/Mart-1, Tyrosinase, Ki-67.

Answer 6

S100: most sensitive marker for melanoma and spindle cell/desmoplastic melanoma. HMB-45: higher specificity for melanoma (primary-metastatic) can help distinguish nevi from melanoma. Melan-A/Mart-1: similar sensitivity and specificity to HMB-45, but with more diffuse and intense staining. Tyrosinase: higher sensitivity than HMB-45 and specificity of 97-100%, sensitivity decreases with increased clinical stage and in metastases. Ki-67: less than 5% of cells in nevi, and 13-30% of cells in malignant melanoma; higher percentages have been noted in Spitz nevi as well.

Question 7

Lentigo maligna.

Answer 7

The preinvasive/in situ form of melanoma located on chronically sun-damaged skin. The appellation lentigo maligna has been used b/c of the lesion’s clinical resemblance to an actinic/solar lentigo and/or b/c of some authors’ unwillingness to label these lesions as a malignancy per se. Most patients present with a slowly enlarging macule or patch. Areas of partial regression within the lesion are not uncommon. Amelanotic lentigo maligna may develop spontaneously or may arise from a previously treated pigmented lentigo maligna. Histologic features related to chronic sun damage such as epidermal atrophy, increased pigmentation in basal keratinocytes, and prominent solar elastosis are present. The melanocytes are increased in number, and as in solar lentigenes, often are disposed as single cells along the basal layer. Nests of melanocytes may be present, but are unevenly distributed across the lesion. A few melanocytes may permeate superficial epidermal layers; involvement of cutaneous adnexal structures is common. Nuclear atypia is variable and may be subtle.

Question 8

Lichen planus vs. lichenoid drug eruption?

Answer 8

LDE should be considered in all pts with clinical features of LP. LDE may appear clinically and histologically identical to LP. The drugs MC associated with LDE are ACEIs, thiazides, beta-blockers, gold salts, antimalarial agents, and penicillamine. The mean age of onset is ~60 yo, about 10 years later than idiopathic LP. LDE has a variable latency period of weeks to years that is dependent on multiple factors. Although the pathogenesis of LDE is unclear, offending drugs likely alter epidermal proteins, acting as haptens to induce an immune response. Idiopathic LP is characterized by monomorphic, violaceous, shiny, flat-topped papules and plaques, characteristically with a fine reticulated pattern of white scale (Wickham striae, which is the macroscopic correlate to histologic hypergranulosis). The flexural surfaces of the wrists, anterior lower legs, and mucous membranes are often affected. LDE is often more polymorphic and may include lesions with a more eczematous, scaly appearance, and is also more likely to present with an atypical distribution of lesions, esp truncal or photodistribution, and to resolve with more pronounced hyperpigmentation. Characteristic histologic features of idiopathic LP include a dense band-like lymphocytic infiltrate at the dermal-epidermal junction, damage to the basal layer, colloid bodies (eosinophilic hyaline bodies originating from apoptosed keratinocytes), irregular acanthosis with “saw-toothed” rete ridges, and overlying hypergranulosis. Although no histologic features can reliably distinguish between idiopathic LP and LDE, certain findings such as the presence of eosinophils, plasma cells, focal parakeratosis, and a deeper perivascular infiltrate may support a diagnosis of LDE.

Question 9

Metastatic Crohn disease.

Answer 9

MCD is an entity characterized by cutaneous, noncaseating granulomas at sites anatomically separate from the GI tract. It is the least common dermatologic manifestation of Crohn disease. In adults, the age of onset of MCD ranges from approximately 29 to 39 years, and the majority of patients have a previous diagnosis of Crohn disease. Twenty percent of patients with MCD may present without classical manifestations of Crohn disease. In these patients, Crohn disease manifests in 2 months to 4 years after the initial presentation of MCD. Cutaneous lesions of MCD may present as papules, plaques, nodules, and ulcerations, which may involve the arms, legs, genitalia, and face. Lesions have also been noted to have predilection for the moist environment of skin folds, including submammary and abdominal creases as well as the perineal and inguinal regions. MCD may present as a solitary lesion or occur in multiple sites and may be painless or tender upon palpation. In the pediatric population, MCD typically presents from the ages of 10 to 14, with about 50% of these patients having concurrent Crohn disease. Of these patients, approximately one-half have active gastrointestinal symptoms. In children who present with MCD lesions without evidence of Crohn disease, subsequent onset of gastrointestinal manifestations occurs from 9 months to 14 years after the initial presentation of MCD. The genitalia appear to be the most common area of involvement in children with MCD; the most common cutaneous manifestation presents as labial, penile, and/or scrotal swelling with or without accompanying erythema. Genital ulcerations have also been reported. MCD presents microscopically as sterile, noncaseating granulomatous inflammation located primarily in the superficial papillary and deep reticular dermis with occasional extension into the subcuticular fat. The granulomas consist of Langerhans giant cells, epithelioid histiocytes, lymphocytes, and occasional plasma cells. The underlying etiology of MCD is currently unknown. It has been suggested that antigens or immune complexes stemming from the GI tract in primary Crohn disease travel through the circulatory system and deposit in the skin, creating perivascular granulomatous features seen on microscopic examination of MCD lesions. Autoimmune cross-reactivity has also been suggested, where antibodies specific to antigens in the GI tract that may be responsible for inflammatory Crohn disease react with skin antigens of similar structure. The differential diagnosis of MCD consists of any granulomatous entities that may involve the skin, including but not limited to cutaneous sarcoidosis, erythema nodosum, pyoderma gangrenosum, hidradenitis suppurativa, mycobacterial disease, and foreign body reaction.

Question 10

Painful skin lesions mnemonic (variation 1 of 3).

Answer 10

ANGEL: Angiolipoma, Neuroma, Glomus tumor, Eccrine spiradenoma, Leiomyoma.

Question 11

Painful skin lesions mnemonic (variation 2 of 3).

Answer 11

LEND AN EGG: Leiomyoma, Eccrine spiradenoma, Neuroma, Dermatofibroma (sometimes), Angiolipoma, Neurilemmoma, Endometrioma, Glomus tumor, Granular cell tumor.

Question 12

Painful skin lesions mnemonic (variation 3 of 3).

Answer 12

BLUE ANGEL: BLUE rubber bleb nevus, Angiolipoma, Neuroma, Glomus tumor, Eccrine spiradenoma, Leiomyoma.

Question 13

What is seen histologically in skin and GI biopsies from patients with acute GVHD?

Answer 13

The skin biopsy initially shows epidermal basal vacuolization and focal epidermal apoptosis with lymphoid infiltration. Bullae formation with epidermal separation can extend to erythroderma, and necrosis is observed in later stages. In grade I, there is vacuolization of the basal keratinocytes; in grade II, there are dyskeratotic keratinocytes and basal cell vacuolization; in grade III, there is increased keratinocyte necrosis and focal basal layer clefting; in grade IV, there is necrosis of the entire epidermis and complete separation from the dermis. There are various degrees of lymphocytic infiltration. The microscopic findings of early GVHD are similar to erythema multiforme, while the severe form resembles toxic epidermal necrolysis.
The GI biopsy shows diffuse edema and mucosal swelling followed by variable crypt cell apoptosis (“exploding” crypts) and a mixed chronic and predominantly lymphoplasmacytic infiltrate, and there can be crypt dropout. In grade I, there is increased crypt apoptosis; in grade II, there is apoptosis with crypt abscess; in grade III, there is crypt necrosis; in grade IV, there is total denudation of mucosal areas. The immunosuppressive drug mycophenolate mofetil can cause variable GI mucosal injury patterns, including GVHD-like changes.
In the skin and GI tissue affected by GVHD, the mechanism of apoptosis is likely similar and caused by alloreactive T lymphocytes targeted to alloantigen on recipient tissue.

Question 14

Erysipelas is caused by (organism). Erysipeloid is caused by (organism).

Answer 14

Erysipelas is caused by S. pyogenes. Erysipeloid is caused by Erysipelothrix rhusiopathiae.

Question 15

Adiaspiromycosis is caused by (organism).

Answer 15

Adiaspiromycosis is caused by Chrysosporium parvum.

Question 16

Define the following terms: acantholysis, acanthosis, bulla, epidermolysis, lichenoid interface change, spongiosis, vacuolar interface change.

Answer 16

Acantholysis is disruption of desmosomes that normally join the keratinocytes of the epidermis, resulting in loss of cohesion and rounding up of the affected cells. Acanthosis is an increase in the thickness of the stratum malpighii. A bulla is an intraepidermal or subepidermal cavity. Intraepidermal bullae may be secondary to either spongiosis or acantholysis. Subepidermal bullae are formed from extensive papillary dermal edema. Epidermolysis is a distinctive alteration of the granular layer characterized by perinuclear clear spaces, swollen and irregular keratohyalin granules, and an increase in the thickness of the granular layer. Lichenoid interface change results from destruction of basal keratinocytes. Destruction and dyskeratosis result in “remodeling” of the basement membrane zone. A bandlike lymphocytic infiltrate usually accompanies the keratinocyte changes. Spongiosis is intercellular intraepidermal edema. Vacuolar interface change results from destruction of the basal keratinocytes characterized by the presence of intracytoplasmic vesicles. The vesicles enlarge, and eventually the basal keratinocytes die; as a result, the integrity of the basal zone of the epidermis is lost.

Question 17

What are the 4 layers of the epidermis?

Answer 17

The stratum corneum is the outermost layer of the epidermis. The fully keratinized cells of this layer are flattened and devoid of nuclei. On acral surfaces, a thin stratum lucidum (clear zone) is present between the stratum corneum and the stratum granulosum. The stratum granulosum is named for the prominent deeply basophilic keratohyalin granules found in flattened keratinocytes. Deep to the stratum granulosum is the stratum spinosum, which is characterized by abundant eosinophilic cytoplasm, ovoid nuclei, and intercellular bridges. The stratum basale (basal cell layer) is the undulating row of cuboidal to columnar cells with minimal cytoplasm and contain proliferating cells for epidermal renewal. The basal cells attach to the basement membrane of the epidermis. The stratum spinosum and the basal cell layer are collectively referred to as the stratum malpighii.

Question 18

What HPV types (in order of frequency) are seen mostly commonly in the following lesions? Plantar wart, common wart, flat (juvenile) wart, oral squamous papilloma, oral focal epithelial hyperplasia (Heck disease), epidermodysplasia verruciformis, laryngeal papillomas, condyloma acuminatum, cervical LSIL, cervical HSIL, cervical AIS and invasive cervical adenocarcinoma.

Answer 18

Plantar wart: 1, 2. Common wart: 2, 1, 4, (HPV 7 in fish and meat handlers). Flat (juvenile) wart: 3, 10. Oral squamous papilloma: 6, 11. Oral focal epithelial hyperplasia (Heck disease): 13, 32. Epidermodysplasia verruciformis: 2, 3, 10, 5, 8. Laryngeal papillomas: 6, 11. Condyloma acuminatum: 6, 11. Cervical LSIL: 6, 11. Cervical HSIL: 16, 18, 31, 33, 35. Cervical AIS: 18. Invasive cervical adenocarcinoma: HPV 16 and 18 are detected with equal prevalence in most subtypes of cervical adenocarcinoma.

Question 19

What are Henderson-Patterson bodies?

Answer 19

Henderson-Patterson bodies = molluscum bodies, seen in molluscum contagiosum. They are eosinophilic intracytoplasmic inclusion bodies (accumulated virus particles) in keratinocytes of stratum spinosum and stratum granulosum.

Question 20

What is myospherulosis?

Answer 20

Myospherulosis, AKA spherulocytosis AKA subcutaneous spherulocystic disease, is an iatrogenic benign mass formed by a foreign body-type granulomatous reaction to lipid-containing material and blood. Clinically, there are solid subcutaneous or dermal nodules. Grossly, is a large saccular cyst-like lesion Histologically, there are saclike structures with fungi-like spherules. The spherules are composed of erythrocytes damaged by endogenous and exogenous fat. The damaged erythrocytes are enclosed by a lipid membrane and later phagocytosed by histiocytes as part of the lipogranulomatous reaction that takes place in adipose tissue. The walls of the spherules are formed due to the physical emulsion phenomenon that occurs between lipid-containing materials and blood. Myospherulosis can be a result of fat necrosis, malignancy such as RCC, endogenous membranocystic degeneration of fat that occurs in lupus, or lipid/petrolatum-based medications being injected or applied to open wounds. It is called MYOspherulosis due to the involvement of skeletal muscle in some patients. It can be mistaken for true fungus, such as Coccidioides, because myospherulosis has parent bodies/pigmented bodies and spherules/endobodies that are similar in size and morphology to Coccidioides; however, myospherulosis has pigmented bodies, while Coccidioides is never pigmented.

Question 21

What are the 3 main types of multinucleated giant cells?

Answer 21

Foreign body giant cells, Langhans giant cells, and Touton giant cells. All three types are transformed macrophages; mononuclear phagocytes fused under the influence of cytokines. Foreign body giant cells have nuclei that are randomly distributed but often aggregate as centrally located, overlapping nuclei. Langhans giant cells have a peripheral ring-like arrangement of nuclei in an arcuate configuration but no rim of clear cytoplasm. Touton giant cells have a ring of nuclei separating a peripheral clear or foamy rim of cytoplasm from central, more eosinophilic cytoplasm. The peripheral cytoplasm appears clear due to high lipid content. Touton giant cells are seen in lesions with high lipid content, such as xanthomas, xanthogranulomas, and fat necrosis. Touton giant cells can also be seen in dermatofibroma. Other types of multinucleated giant cells include epithelium-derived MGCs, which can be prominent in certain viral infections such as measles (Warthin-Finkeldey cells), RSV, HSV/VZV, and parainfluenza. Also, MCGs derived from neoplastic cells may be formed in a variety of neoplasms.

Question 22

Does Merkel cell carcinoma stain with TTF-1?

Answer 22

No.

Question 23

When is SLN biopsy indicated in melanoma, according to ASCO and Society of Surgical Oncology guidelines?

Answer 23

SLN bx is recommended for intermediate-thickness melanomas (Breslow thickness 1-4 mm) of any anatomic site for accurate staging. SLN bx may be indicated for thick melanomas (T4, Breslow thickness >4 mm) for staging and to facilitate regional disease control. Evidence does not support routine SLN bx of thin melanomas (<1 mm) except with high risk features (ulceration, mitotic rate 1/mm^2 or greater, Breslow thickness 0.75-0.99 mm) when benefits of staging outweight risks of the procedure. Complete lymph node dissection is recommended for all patients with a positive SLN bx.

Question 24

What is a Triton tumor?

Answer 24

A benign Triton tumor is a neuromuscular hamartoma/choristoma. It is a rare developmental lesion of mature skeletal muscle and nerve. Microscopically, is made up of multiple nodules, each 3-5 mm, separated by narrow bands of connective tissue. Nodules are composed of fasicles of striated muscle of varying size with nerve fibers (myelinated or not) within same perimysial fibrous sheath. Stroma may be more cellular with bland spindle cells and resemble fibromatosis. A malignant Triton tumor is made up of both malignant schwannoma cells and malignant rhabdomyoblasts, and is classified as a MPNST with rhabdomyosarcomatous differentiation. The name “triton” was first used in reference to observation of supernumerary limbs containing bone and muscle growing the backs of tritons (a name given to some species of sea snails) after the implantation of the sciatic nerve into the soft tissues of the back.

Question 25

What is the difference between epidermotropism and exocytosis in dermpath?

Answer 25

Epidermotropism is lymphocytes in epidermis with relative absence of spongiosis: term usually reserved for mycosis fungoides. Exocytosis is lymphocytes in the epidermis with associated spongiosis: term usually used when discussing spongiotic dermatitis.

Question 26

What are Medlar bodies?

Answer 26

Medlar bodies, also called chromo bodies, are the adaptive tissue form ("sclerotic cells") of a specific group of dematiaceous fungi that cause chromoblastomycosis. They are round, brown, thick-walled structures that are 4-12 µm in diameter, resembling overlapping copper pennies. They divide by septation, resembling hot-cross buns.

Question 27

Chromoblastomycosis is also called ___.

Answer 27

Chromoblastomycosis is also known as "Chromomycosis," "Cladosporiosis," "Fonseca's disease," "Pedroso's disease," "Phaeosporotrichosis," and "Verrucous dermatitis." It is a long-term fungal infection of the skin and subcutanous tissue (a chronic subcutaneous mycosis). The infection occurs most commonly in tropical or subtropical climates, often in rural areas. It is caused by specific types of dematiaceous fungi which become implanted under the skin, often by thorns or splinters. The term chromoblastomycosis is restricted to the cases in which sclerotic cells/Medlar bodies/chromo bodies (an adaptive tissue form of the fungi) are present in tissue.

Question 28

What is a BLK in dermpath? What is the clinical presentation and epidemiology?

Answer 28

Benign lichenoid keratosis, also called lichenoid benign keratosis, lichen planus-like keratosis (LPLK), solitary lichen planus, and involuting lichenoid plaque. BLKs are usually solitary, discrete, slightly raised lesions of short duration, measuring 3-10 mm in diameter. The sudden appearance of the lesion is often a striking feature. Lesions are violaceous or pink, often with a rusty tinge. There may be a thin, overlying scale. There is a predilection for the arms and presternal area of middle-aged and elderly women. Lesions are sometimes mildly pruritic or "burning." Clinically, BLK is usually misdiagnosed as a BCC or Bowen's disease. BLK is a heterogeneous condition which usually represents the attempted cell-mediated immune rejection of any of several different types of epidermal lesion, most often solar lentigo.

Question 29

Benign lichenoid keratosis (BLK)/Lichen planus-like keratosis (LPLK) histologic appearance.

Answer 29

There is a florid lichenoid reaction pattern with numerous apoptotic keratinocytes in the basal layer and accompanying mild vacuolar change. The infiltrate is usually quite dense and often includes a few plasma cells, eosinophils, and even neutrophils in addition to the lymphocytes and macrophages. The infiltrate may obscure the dermo-epidermal interface. Pigment incontinence may be prominent. This is so in the late (regressed, atrophic) stage; epidermal atrophy and papillary dermal fibrosis are also present. There may be mild atypia of keratinocytes but this is never as marked as it is in a lichenoid solar keratosis. There is often mild hyperkeratosis and focal parakeratosis. The presence of parakeratosis allows a distinction to be made with lichen planus. Hypergranulosis is not as pronounced as in lichen planus. A contiguous solar lentigo or large cell acanthoma is sometimes seen.

Question 30

A small subset of cases of the polyostotic form of fibrous dysplasia (~3%) occurs along with endocrine abnormalities and coast of Maine cafe-au-lait spots, a triad called ___ syndrome.

Answer 30

A small subset of cases of the polyostotic form of fibrous dysplasia (~3%) occurs along with endocrine abnormalities and coast of Maine cafe-au-lait spots, a triad called McCune-Albright syndrome.

Question 31

Kaposi sarcoma overview.

Answer 31

Kaposi sarcoma (KS) is a low-grade vascular tumor associated with Kaposi sarcoma herpesvirus/human herpesvirus 8 (KSHV/HHV8) infection. Kaposi sarcoma lesions predominantly present at mucocutaneous sites, but may involve all organs and anatomic locations. Recognized epidemiologic-clinical forms of KS include classic, African (endemic), AIDS-associated (epidemic), and iatrogenic KS. New clinical manifestations have been described, such as antiretroviral therapy–related KS regression or flares. Kaposi sarcoma lesions evolve from early (patch stage) macules into plaques (plaque stage) that grow into larger nodules (tumor stage). Newer histologic variants include anaplastic, hyperkeratotic, lymphangioma-like, bullous, telangiectatic, ecchymotic, keloidal, pyogenic granuloma–like, micronodular, intravascular, glomeruloid and pigmented KS, as well as KS with sarcoidlike granulomas and KS with myoid nodules. Latency-associated nuclear antigen (HHV8) is the most specific immunohistochemical marker available to help distinguish KS from its mimics. KS remains one of the most common AIDS-defining malignancies.

Question 32

Kaposi sarcoma pathogenesis.

Answer 32

With the advent of genomic technologies, proliferating KS spindle tumor cells are now known to be of endothelial origin, confirming former studies that used histochemistry and ultrastructural findings. Circulating blood mononuclear and endothelial “progenitor cells” are believed to be the source of early KS lesions. Infection with HHV8 reprograms the host's blood endothelial cells so that they resemble lymphatic endothelium, upregulating several lymphatic-associated genes such as lymphatic vessel endothelial receptor 1 (LYVE1), podoplanin, and vascular endothelial growth factor receptor 3 (VEGFR3). However, HHV8 infection alone appears to be insufficient for the development of KS. Kaposi sarcoma progression relies also on some degree of host immune dysfunction and the local inflammatory milieu. Kaposi sarcoma growth involves the upregulation of many key HHV8 gene products, such as the latency-associated nuclear antigen (LANA-1 or LNA-1). Like other herpesviruses, HHV8 remains latent within cells and has developed a variety of mechanisms to evade the host immune system.

Question 33

For the 4 types of Kaposi sarcoma, list the epidemiology, clinical distribution, and behavior.

Answer 33

Classical type: Mainly males aged 40-70 years, of Mediterranean or Jewish Ashkenazi origin. Skin of the lower extremities, but mucosal and visceral lesions may develop. Indolent. African type: Middle-aged black adults and children from equatorial Africa. Multiple localized skin tumors, involving lower extremities and/or lymph nodes. Progressive; lymphadenopathic form is aggressive. AIDS-associated type: Mainly homosexual males and IVDUs aged 20-50 years; now equally affects women and children in Africa. Disseminated mucocutaneous and visceral involvement. Aggressive; lesions may regress or flare with initiation of antiretroviral therapy. Iatrogenic type: Immunosuppressed persons of any age from autoimmune disease, drugs, or transplantation. Localized mucocutaneous or disseminated KS, with possible visceral lesions. Variable; may regress after immunosuppression is discontinued.

Question 34

Histologic appearance of Kaposi sarcoma.

Answer 34

Early patch-stage KS is characterized by abnormal vessels lined by thin endothelial cells dissecting the dermis. Ramifying proliferating vessels often surround larger ectatic vessels and skin adnexa, producing the so-called promontory sign. This sign is not pathognomonic for KS, as it has also been described in other vascular lesions including benign vascular tumors and angiosarcoma. Sparse chronic inflammatory cells, extravasated red blood cells, and hemosiderin-laden macrophages are frequently present in patch KS lesions. These early histologic changes may be inconspicuous, and for that reason can be easily missed on biopsy. Plaque-stage KS lesions are characterized by a proliferation of both spindle cells and vessels, which in the skin involve most of the dermis, and sometimes even the subcutis. Well-developed KS tumors consist of several fascicles of these spindle-shaped tumor cells, often admixed with a variable chronic inflammatory infiltrate composed of lymphocytes, plasma cells, and dendritic cells. Kaposi sarcoma lesions also contain several hemosiderin-laden macrophages. Iron staining may help distinguish KS from similar-appearing interstitial granuloma annulare lesions that lack iron. In cross section, KS nodules display a sievelike appearance caused by the transection of spindle cells with intervening slitlike spaces. Eosinophilic and PAS–positive hyaline globules are a common finding in advanced KS lesions. These globules may be located within lesional cells or extracellularly. Typical KS lesions are devoid of marked cellular pleomorphism, necrosis, or a significant number of mitotic figures. In rare instances, AIDS-KS lesions may harbor concomitant pathologic findings, usually an opportunistic pathogen (eg, cryptococcosis, mycobacterial granulomas, or molluscum contagiosum).

Question 35

What are pre-Kaposi sarcoma lesions and anaplastic Kaposi sarcoma?

Answer 35

These are at the two opposite ends of the spectrum of Kaposi sarcoma. Pre-KS lesions are also referred to as an "in situ" form of KS. These pre-KS lesions are characterized by groups of abnormal capillary-like vessels admixed with an inflammatory infiltrate, similar to patch-stage KS lesions. They are associated with lymphangiogenesis arising in the setting of chronic lymphedema. On the other end of the spectrum is anaplastic KS, sometimes referred to as pleomorphic KS. Anaplastic KS is an infiltrative, solid proliferation of spindle cells without vascular spaces, seen mainly in AIDS involving acral sites. This aggressive variant displays a greater degree of cellular and nuclear atypia, high mitotic index (eg, 5 to 20 mitoses per 10 high-power fields), and occasional necrosis.

Question 36

IHC for Kaposi sarcoma.

Answer 36

Kaposi sarcoma lesional cells stain positively with the endothelial markers factor VIII–related antigen, CD31 (PECAM-1), and CD34. CD34 tends to show stronger expression than CD31 in advanced-stage lesions of KS. KS spindle cells also express several lymphatic specific markers such as D2-40 (which binds to the podoplanin antigen), LYVE-1 (a homologue of the CD44 glycoprotein receptor for hyaluronan), VEGFR-3 (the receptor for vascular endothelial growth factor C), and Prox-1. Bcl-2 also shows positivity in KS, related to the tumor's mechanisms of resisting apoptosis. The identification and localization of HHV8 within KS lesional cells by using LNA-1 (also called LANA-1) is the most diagnostically helpful immunostaining technique available to differentiate KS from its mimics. LNA-1 immunoreactivity in KS cells appears as stippled nuclear staining. However, HHV8 is not entirely limited to KS and has been detected in some angiosarcomas, hemangiomas, and dermatofibromas. LNA-1 IHC is favored over PCR detection of HHV8 in the evaluation of problematic vascular proliferations because contaminating mononuclear inflammatory cells may also harbor this herpesvirus, especially in HIV-positive patients.

Question 37

Histologic differential diagnosis for the patch, plaque, and nodular stages of Kaposi sarcoma.

Answer 37

Clinical history, such as HIV infection or status post transplant, may strongly support the diagnosis of KS. The differential diagnosis of patch-stage KS includes targetoid hemosiderotic hemangioma, fibrous histiocytoma, and interstitial granuloma annulare. The differential diagnosis of plaque-stage KS includes tufted angioma, targetoid hemosiderotic hemangioma, microvenular hemangioma, and acroangiodermatitis (“pseudo-Kaposi sarcoma”). The differential diagnosis of nodular KS includes bacillary angiomatosis, other vascular tumors (eg, spindle cell hemangioma and Kaposiform hemangioendothelioma), fibrohistiocytic tumors (eg, cellular, angiomatoid, and atypical variants of fibrous histiocytoma, and dermatofibrosarcoma protuberans), resolving dermal fasciitis, spindle cell melanoma, and several other spindle cell mesenchymal neoplasms (eg, cutaneous leiomyosarcoma).

Question 38

What are nonmalignant medical conditions associated with reactive eosinophilia?

Answer 38

Allergic reactions (drug reactions, asthma), parasitic infections (strongyloidiasis), schistosomiasis, filariasis, toxocariasis), metabolic abnormalities (adrenal insufficiency), humoral immunodeficiency (hyperimmunoglobulin E syndrome (Job syndrome), Wiskott-Aldrich syndrome, hyperimmunoglobulin M syndrome, immunoglobulin A deficiency), pulmonary eosinophilias (eosinophilic granulomatosis with polyangiitis (formerly Churg-Strauss syndrome), allergic bronchopulmonary aspergillosis, chronic and acute idiopathic eosinophilic pneumonias), autoimmune blistering skin diseases (dermatitis herpetiformis, bullous pemphigoid).

Question 39

How can angiolymphoid hyperplasia with eosinophilia be distinguished from Kimura lymphadenopathy?

Answer 39

ALHE can have a striking histologic similarity to KL. ALHE is present mostly in Caucasians and can be confused with early stage KL. ALHE more often affects females and is seen in soft tissues and superficial dermis forming clusters of eosinophilic cells. ALHE typically presents as cutaneous papules rather than a mass lesion, and histology reveals non-nodal collections of eosinophils with hypertrophic endothelial cells that protrude and occlude vascular lumina in a tombstone pattern. Lymphadenopathy, which is an essential feature in KL, is not frequently seen in ALHE.

Question 40

Several named syndromes are associated with eosinophilia and eosinophilic infiltration of specific organs: eosinophilic cellulitis (__ syndrome), eosinophilic pneumonia (__ syndrome), eosinophilic fasciitis (__ syndrome), and eosinophilic vasculitis (__ syndrome).

Answer 40

Several named syndromes are associated with eosinophilia and eosinophilic infiltration of specific organs: eosinophilic cellulitis (Well syndrome), eosinophilic pneumonia (Loeffler syndrome), eosinophilic fasciitis (Shulman syndrome), and eosinophilic vasculitis (Churg-Strauss syndrome).

Question 41

What are some entities that cause a sinus pattern of nonneoplastic proliferation in lymph node?

Answer 41

Sinus histiocytosis, a nonspecific reaction to numerous lymph node stimuli. Sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease). Lymphangiogram effect. Whipple disease. Hemophagocytic syndrome. Dermatopathic lymphadenitis.

Question 42

What is a white sponge nevus?

Answer 42

AKA Cannon disease AKA familial white folded mucosal dysplasia AKA hereditary leukokeratosis. An AD disease with incomplete penetrance and variable expressivity. Prominent parakeratosis, acanthosis, and spongiosis of nonkeratinized squamous mucosa. Rete are blunted. Inflammation is usually not present. Pathognomonic: Pap stain of exfoliative cytology shows a characteristic perinuclear eosinophilic condensation of keratin tonofilaments. Most commonly intraoral, with buccal mucosa most common intraoral site. DDx: hereditary benign intraepithelial dyskeratosis, leukoedema, oral hairy leukoplakia.

Question 43

What is hairy leukoplakia AKA oral hairy leukoplakia?

Answer 43

An EBV-associated epithelial hyperplasia usually on the lateral tongue in immunocompromised patients, most commonly HIV+ males. The disease correlated with viral load and CD4 counts. Although not an AIDS-defining disease, is a marker of HIV disease progression. Micro: Marked acanthosis and parakeratosis. Epithelial hyperplasia with elongation of rete ridges. Viral cytopathic effect (balloon cells) in spinous layer. Candida can be seen in superficial keratin - coinfection is a common finding in OHL. Very little if any inflammation. No dysplasia. DDx: Frictional keratosis. Hyperplastic candidiasis. Leukoplakia. Lichen planus.

Question 44

Is oral hairy leukoplakia an AIDS-defining illness?

Answer 44

No. OHL is an EBV-associated epithelial hyperplasia usually on the lateral tongue in immunocompromised patients, most commonly HIV+ males but seen in transplant patients as well. The disease correlated with viral load and CD4 counts. Although not an AIDS-defining disease, is a marker of HIV disease progression.

Question 45

What is herpangina?

Answer 45

Herpangina is a common viral infection of young children associated with blisters of soft palate or tonsillar pillars. It is caused by viruses belonging to the Enterovirus group (coxsackievirus, poliovirus, echovirus). Coxsackie A16 virus is the most common cause. Transmission is direct contact, usually oral-fecal route.

Question 46

What virus is the most common cause of herpangina?

Answer 46

Herpangina is a common viral infection of young children associated with blisters of soft palate or tonsillar pillars. It is caused by viruses belonging to the Enterovirus group (coxsackievirus, poliovirus, echovirus). Coxsackie A16 virus is the most common cause, but other coxsackie viruses usually associated include A1 to A6, A8, A10, or A22.

Question 47

What is hand, foot, and mouth disease?

Answer 47

A common viral illness of infants and children, which causes fever and blister eruptions of mouth and/or skin. Caused by virus belonging to Enterovirus group. Transmission is by direct contact. Virus is found in secretions, including saliva, nose and throat secretions, blister fluid, and stools.

Question 48

What is Heck disease?

Answer 48

AKA focal epithelial hyperplasia AKA multifocal epithelial hyperplasia. A benign, virus-induced epithelial proliferation of oral mucosa associated with HPV types 13 and 32. Majority of cases are in children. Micro: Prominent acanthosis and elongated broad rete ridges (since the thickened epithelium extends upward, elongated rete are at same depth as adjacent normal rete ridges). May see papillary surface. Mitosoid cells (represents ballooning and nuclear degeneration; represents an altered nucleus resembling a mitosis in an otherwise normal stratified squamous epithelium; can be seen throughout epithelium); do not misinterpret mitosoid cells as atypia. Koilocytic change in superficial keratinocytes can be seen. No dyskeratosis and/or atypia. DDx: Papilloma. Condyloma acuminatum. Oral verruca vulgaris.

Question 49

What HPV types cause Heck disease (focal epithelial hyperplasia/multifocal epithelial hyperplasia)?

Answer 49

HPV types 13 and 32.

Question 50

What sites are affected in pemphigus vulgaris?

Answer 50

PV is an autoimmune mucocutaneous disease characterized by intraepithelial blistering. Etiology is circulating autoantibodies to desmoglein 1 and 3 adhesion molecules of squamous epithelium, which inhibit cell-cell adhesion resulting in acantholysis and blister formation. Mucous membranes: oral, nasal, esophagus, larynx, nasopharynx, conjunctivae, genitalia, anal mucosa. Cutaneous sites are mostly on intertriginous areas, trunk, head, and neck. Mucosal PV may be the only manifestation of disease or may precede cutaneous PV by an average of 5 months. >90% of patients will have oral involvement during disease course.

Question 51

What is the etiology of pemphigus vulgaris?

Answer 51

PV is an autoimmune mucocutaneous disease characterized by intraepithelial blistering. Etiology is circulating autoantibodies to desmoglein 1 and 3 adhesion molecules of squamous epithelium, which inhibit cell-cell adhesion resulting in acantholysis and blister formation (suprabasal bullae formation with intraepithelial clefting).

Question 52

What is the characteristic direct immunofluorescence finding in pemphigus vulgaris?

Answer 52

Homogenous staining ("fishnet" pattern) of IgG in intercellular desmosomal areas at all levels of the epidermis.

Question 53

What sites are affected in mucous membrane pemphigoid AKA cicatricial pemphigoid?

Answer 53

MMP is a chronic, blistering mucocutaneous autoimmune disease generally presenting in 6th or 7th decade and M:F=1:2. Oral cavity is frequently affected, with gingival involvement seen in >60%. Ocular lesions occur in ~40% of patients with oral MMP. Upper aerodigestive tract can also be affected. Micro shows subepithelial clefting, intact basal cells, and a sparse inflammatory cell infiltrate in superficial lamina propria.

Question 54

What is the characteristic direct immunofluorescence finding in mucous membrane pemphigoid (cicatricial pemphigoid)?

Answer 54

Micro shows subepithelial clefting, intact basal cells, and a sparse inflammatory cell infiltrate in superficial lamina propria. Direct immunofluorescence shows a continuous linear band of IgG and C3 at basement membrane zone (can also see IgM and IgA).

Question 55

What is seen in direct immunofluorescence of lichen planus?

Answer 55

DIF is not specific or diagnostic. May show linear or granular deposits of fibrin or fibrinogen. Deposits of C3, IgM, IgG, and IgA occasionally seen.

Question 56

What is Riga-Fede disease?

Answer 56

AKA traumatic ulcer, traumatic ulcer with stromal eosinophilia, eosinophilic granuloma of tongue, traumatic granuloma, atypical histiocytic granuloma. It is a chronic traumatic ulceration of oral mucosa with unique histopathologic features. Riga-Fede disease specifically refers to trauma to the soft tissue (ventral tongue or inner lower lip) in newborns or infants from natal or neonatal teeth. In children, traumatic ulcer is often due to thermal or electrical burns or parafunctional habits. In adults, traumatic ulcer is often due to fractured and/or malposed teeth or parafunctional habits. Micro: Ulcer bed composed of granulation tissue with mixed inflammatory cell infiltrate of lymphocytes, histiocytes, neutrophils, and occasionally plasma cells. Inflammation including scattered eosinophils extends into underlying muscle.

Question 57

What oral lesions are associated with pseudoepitheliomatous hyperplasia?

Answer 57

Granular cell tumor. Hyperplastic candidiasis. Inflammatory papillary hyperplasia. Median rhomboid glossitis. Necrotizing sialometaplasia. Mucosal ulcers (traumatic ulcers, aphthous ulcers, herpetic ulcers, nonhealing extraction sockets). Although PEH can have rete deeply extending into lamina propria, anastamosing of rete, and keratin pearl formation, there will be no or very little cytologic atypia, and while mitotic figures can be present, they will not be atypical.

Question 58

What are the definitions of squamous papilloma, verrucae vulgaris, and condyloma accuminatum?

Answer 58

SP: Benign proliferation of squamous epithelium in exophytic pattern with branching fibrovascular tissue cores exhibiting papillary pattern causally related to HPV infection (subtypes 6 and 11 detected in ~50% of cases, rarely HPV 16 detected). VV (AKA common wart or oral wart): Benign HPV-induced (subtypes 2, 4, 6, 40, or 57 detected in 100% of cases) proliferation of squamous epithelium, usually on skin, but also in oral cavity. CA (AKA veneral wart): HPV-related (subtypes 2, 6, 11, 53, or 54 in oral area, rarely 16, 18, or 31 (usually anogenital)) proliferation of squamous epithelium of genitalia, perianal region, oral cavity, or larynx.

Question 59

What is an Abrikossoff tumor?

Answer 59

AKA granular cell tumor AKA granular cell myoblastoma AKA granular cell nerve sheath tumor AKA granular cell schwannoma.

Question 60

What are etiologies for pyogenic granuloma in the oral cavity? What is the epidemiology?

Answer 60

Pyogenic granuloma AKA lobular capillary hemangioma AKA epulis granulomatosus AKA pregnancy tumor (epulis gravidarum). Etiologies include poor oral hygiene, local irritants (fractured tooth, poor restoration), localized trauma (biting), and hormones (increased in pregnancy and oral contraceptive use. Most common in children and young adults. In up to age 18, M>F but in adults M:F = 1:2. About 1% of pregnant women develop PG, and is related to hormonal influences on vessels. Gingiva is the most common site of oral cavity PG.

Question 61

What is the cell of origin for pyogenic granuloma/lobular capillary hemangioma?

Answer 61

Bicellular origin from endothelial and pericyte cells.

Question 62

What is oropharyngeal carcinoma?

Answer 62

Basically is a squamous cell carcinoma of oropharynx, the sites including soft palate, tonsils, uvula, base of tongue, and oropharyngeal wall comprising Waldeyer ring. Is also called oropharyngeal squamous cell carcinoma (OPSCC). What is typically called oral squamous cell carcinoma involves the sites of tongue (lateral and ventral), floor of mouth, lip, retromolar trigone, gingiva, buccal mucosa, and palate. HPV+ OPSCC is nonkeratinizing, while HPV- OPSCC is keratinizing. Other subtypes include: Hybrid-type OPSCC, which has features of both nonkeratinizing OPSCC and keratinizing SCC; is HPV+ most of the time. Lymphoepithelial-like OPSCC, which is similar in histology to EBV-related nasopharyngeal carcinoma; is HPV+. Papillary OPSCC, which is an uncommon variant; most are HPV+.

Question 63

When McCune-Albright syndrome is associated with intramuscular myxomas, it is called ___ syndrome.

Answer 63

When McCune-Albright syndrome (hyperfunctioning endocrinopathies, including precocious puberty, fluctuating thelarchy, hyperthyroidism, growth hormone excess, rickets/osteomalacia; as well as skin hyperpigmentation/cafe au lait spots) is associated with intramuscular myxomas, it is called Mazabraud syndrome.

Question 64

What is the incubation period for cutaneous anthrax?

Answer 64

This form of anthrax occurs after spores are introduced beneath the skin by inoculation or contamination of a preexisting lesion or break in the skin. The incubation period is 2–7 days (rarely after 1 day) but more often lasts between 2 and 5 days. Lesions begin as small, painless pimples on exposed skin and progress to vesicles and eventually an ulceration that develops a black scab (eschar) at the center (within 2–6 days).

Question 65

In nature, approximately __% of human cases of anthrax are cutaneous infections, as opposed to inhalation anthrax or GI anthrax.

Answer 65

In nature, approximately 95% of human cases of anthrax are cutaneous infections, as opposed to inhalation anthrax or GI anthrax.

Question 66

What are fatality rates for the 3 forms of anthrax?

Answer 66

The fatality rate of inhalation anthrax approaches 90%, even with antibiotic therapy. Untreated cutaneous anthrax can have a fatality rate of up to 20%, but fatalities are rare (1%) with proper antibiotic treatment. The fatality rate for GI anthrax is 25%–60%.

Question 67

Inhalation, cutaneous, and GI anthrax can be complicated by meningitis, which occurs in about _% of cases.

Answer 67

Inhalation, cutaneous, and GI anthrax can be complicated by meningitis, which occurs in about 5% of cases.

Question 68

What are the most common benign and most common malignant vulvar adnexal lesions?

Answer 68

Most common benign: hidradenoma papilliferum. Most common malignant: extramammary Paget disease.

Question 69

What are some epithelial cysts that can be seen in the vulva?

Answer 69

Vulvar epithelial cysts are derived from a variety of resident structures. Those thought to arise from remnants of urogenital sinus include urogenital sinus cysts, major (Bartholin gland) and minor vestibular gland cysts, paraurethral (Skene gland) cysts, Wolffian-like duct cyst, and cysts of canal of Nuck. Cysts derived from the overlying epidermis, hair follicles, and apocrine glands include epidermoid cysts, pilar or trichilemmal cysts, dermoid cysts, and hidrocystomas. Less-common entities include steatocystomas and cysts of anogenital mammary-like glands (previously reported as milk cysts of the supernumerary mammary glands).

Question 70

What are the 3 most common sites to be involved by myeloid sarcoma?

Answer 70

Skin, bones, GI tract.

Question 71

What is the PTEN gene? In what tumors is it often mutated?

Answer 71

Phosphatase and tensin homolog (PTEN) gene is on chromosome band 10q23.31. In addition to its role as a tumor suppressor, it has important roles in embryogenesis and maintenance of physiologic functions in many organ systems and is constitutively expressed in normal tissues. It is one of the most frequently inactivated genes in sporadic cancer. Sporadic mutations of PTEN occur frequently in many tumors such as glioblastoma, breast carcinoma, endometrial carcinoma, thyroid neoplasms, skin neoplasms, and advanced prostate cancer.

Question 72

Clear cell sarcoma (CCS), which is also known as melanoma of soft parts, is a rare aggressive tumor that preferentially affects young adults and typically arises in the deep soft tissues of the lower extremities. CCS share many features with malignant melanoma, including expression of melanoma markers, but how are they different in regard to molecular mutations?

Answer 72

CCS share many features with malignant melanoma, including expression of melanoma markers, but, in contrast to most melanomas, they lack BRAF (v-raf murine sarcoma viral oncogene homolog B1) mutations. In addition, most CCS show rearrangement of the EWSR1 (Ewing sarcoma breakpoint region 1) locus, which in most cases leads to fusion of the EWSR1 gene with the activating transcription factor-1 gene (ATF1) in a recurrent translocation, t(12;22)(q13;q12). This translocation is not present in melanoma. On rare occasions, CCS of soft tissues can also show EWSR1-CREB1 (cAMP responsive element–binding protein 1) gene fusion.

Question 73

What are the 3 morphologic types of lymphangiomas?

Answer 73

Capillary, or simple, lymphangiomas are usually found in superficial skin and composed of capillary-sized, thin-walled vessels. Cavernous lymphangiomas are subcutaneous lesions composed of mildly dilated large spaces that are larger than those seen in capillary lymphangiomas. Cystic hygromas are most common in the neck and composed of large, dilated, cystic lymphatic spaces. Combinations of the 3 types can sometimes be found in a single lesion. Differentiating lymphangiomas on the basis of histologic type appears without clinical implications.

Question 74

Primary vulvar adenocarcinomas are classified into what 3 entities?

Answer 74

Primary vulvar adenocarcinomas are rare, with a poorly understood histogenesis. They are classified into (a) extramammary Paget disease, (b) sweat gland carcinoma, and (c) breast-like adenocarcinoma, and are distinguished from adenocarcinoma originating in the Bartholin glands. Extramamamary Paget disease has large pale staining tumor cells, usually in the lower epidermis, in nests, glandular spaces or continuously along the basement membrane. It may be associated with urothelial carcinoma or anorectal carcinoma. Sweat gland carcinoma derives from native apocrine sweat glands, is usually ER-, PR-, and composed of glandular or papillary cords and tubules, with variable pagetoid components. Breast-like adenocarcinoma may originate from anogenital ER+, PR+ mammary like glands in the interlabial sulci, and is often accompanied by these native glands.

Question 75

What tumors are seen commonly in tuberous sclerosis (the "major features" as set forth in a consensus statement from the Diagnostic Criteria Committee of the National Tuberous Sclerosis Association)?

Answer 75

Facial angiofibromas (adenoma sebaceum) or forehead plaque. Nontraumatic ungual or periungual fibroma. >3 hypomelanotic macules. Shagreen patch (connective tissue nevus). Multiple retinal nodular hamartomas. Cortical tuber. Subependymal nodule. SEGA. Cardiac rhabdomyoma, single or multiple. LAM. Renal AML. Definite TSC is either 2 major features or one major plus 2 minor features.

Question 76

MEN1 manifests with pituitary adenomas, parathyroid adenomas, and pancreatic islet cell tumors. What are nonendocrine lesions associated with MEN1?

Answer 76

Facial angiofibromas, collagenomas, lipomas, and meningiomas.

Question 77

What tumors occur in Carney complex?

Answer 77

Cutaneous lentigenes (simple lentigos). Blue nevi, particularly the cellular blue nevus. Cardiac myxomas (as well as myxomas of breast, female genital tract, and skin (especially on eyelid and external ear)). Endocrine tumors including thyroid follicular adenomas, pituitary adenomas (GH-secreting), and the so-called primary pigmented nodular adrenocortical disease (a form of multinodular hyperplasia of the adrenal cortex that causes Cushing syndrome). Large-cell calcifying Sertoli cell tumor. Psammomatous melanotic schwannoma.

Question 78

For the following clinical syndrome(s), give the causative agent(s) (list most common first): mycobacterial skin infection.

Answer 78

M. fortuitum-chelonae, M. marinum, M. haemophilum, M. ulcerans, M. leprae.

Question 79

For the following clinical syndrome(s), give the causative agent(s) (list most common first): cutaneous larva migrans.

Answer 79

Ancylostoma braziliensis.

Question 80

For the following clinical syndrome(s), give the causative agent(s) (list most common first): bacterial cellulitis (most common overall, animal bite-associated, freshwater-associated, and saltwater-associated).

Answer 80

Most common overall: S. pyogenes (GAS). Animal bite-associated: Pasteurella multocida. Freshwater-associated: Aeromonas hydrophila. Saltwater-associated: Vibrio vulnificus.

Question 81

For the following clinical syndrome(s), give the causative agent(s) (list most common first): tinea versicolor.

Answer 81

Malassezia furfur.

Question 82

For the following clinical syndrome(s), give the causative agent(s) (list most common first): leprosy (Hansen disease).

Answer 82

Mycobacterium leprae.

Question 83

For the following clinical syndrome(s), give the causative agent(s) (list most common first): superficial (noninvasive) mycoses (dermatophytosis (Tinea capitis, Tinea crusis, etc.), Black piedra, White piedra, Tinea versicolor, Tinea nigra palmaris/plantaris).

Answer 83

Dermatophytosis (Tinea capitis, Tinea cruris, etc.): Epidermophyton, Microsporon, Trichophyton spp. Black piedra: Piedraia hortae. White piedra: Trichosporon beigelii. Tinea versicolor: M. furfur. Tinea nigra palmaris/plantaris: Phaeoannelomyces werneckii.

Question 84

For the following clinical syndrome(s), give the causative agent(s) (list most common first): cutaneous and subcutaneous mycoses (Sporotrichosis, Chromoblastomycosis, Lobomycosis, Phaeohyphomycosis, eumycotic mycetoma, Rhinosporidiosis).

Answer 84

Sporotrichosis: Sporothrix shenckii. Chromoblastomycosis: Phialophora, Cladosporium, Fonsacea. Lobomycosis: Loboa loboi. Phaeohyphomycosis: Exophiala jeanselmei, Phialophora, Wangiella dermatitidis. Eumycotic mycetoma: Exophiala, Wangiella, P. boydii (scedosporium). Rhinosporidiosis: Rhinosporidium seeberi.

Question 85

For the following clinical syndrome(s), give the causative agent(s) (list most common first): rhinoscleroma.

Answer 85

Klebsiella rhinoscleromatosus.

Question 86

For the following clinical syndrome(s), give the causative agent(s) (list most common first): actinomycotic mycetoma (Madura foot).

Answer 86

Actinomyces, Nocardia, Streptomyces.

Question 87

For the following clinical syndrome(s), give the causative agent(s) (list most common first): erysipelas and erysipeloid.

Answer 87

Erysipelas: S. pyogenes (GAS). Erysipeloid: Erysipelothrix rhusiopathiae.

Question 88

For the following clinical syndrome(s), give the causative agent(s) (list most common first): roseola infantum (exanthem subitum).

Answer 88

HHV-6.

Question 89

For the following clinical syndrome(s), give the causative agent(s) (list most common first): fifth disease (erythema infectiosum, slapped-cheek disease).

Answer 89

Parvovirus B19.

Question 90

For the following clinical syndrome(s), give the causative agent(s) (list most common first): adiaspiromycosis.

Answer 90

Chrysosporium parvum.

Question 91

For the following clinical syndrome(s), give the causative agent(s) (list most common first): fungal external otitis.

Answer 91

Aspergillus niger.

Question 92

For the following clinical syndrome(s), give the causative agent(s) (list most common first): hand-foot-mouth disease.

Answer 92

Coxsackie A.

Question 93

What is schistosomiasis (AKA bilharzia)?

Answer 93

Schistosomiasis is caused by digenetic blood trematodes. The three main species infecting humans are Schistosoma haematobium, S. japonicum, and S. mansoni. Two other species, more localized geographically, are S. mekongi and S. intercalatum. In addition, other species of schistosomes, which parasitize birds and mammals, can cause cercarial dermatitis in humans.

Question 94

A Tzanck smear is used to aid in diagnosis of infection with the Herpes virus, including herpes simplex, varicella, and zoster. Tzanck smears are performed less commonly than in the past because of the availability of immunofluorescence tests for these agents. How are Tzanck smears made?

Answer 94

Clean an area with an intact vesicle for best results. If no intact vesicles are present, use the edge of the most recently appearing erosion or ulcer. Remove a blister roof with a no. 15 blade, blot any excess blister fluid, then scrape the base of the vesicle, erosion, or ulcer with the scalpel blade, spreading a thin layer of the resultant material onto a glass slide. After staining, if typical HSV cytopathic effect is observed, the diagnosis can be made.

Question 95

The association of adenomatous polyposis with prominent skin and soft tissue manifestations has been designated ___ syndrome. The association of adenomatous polyposis and a brain tumor is called ___ syndrome.

Answer 95

The association of adenomatous polyposis with prominent skin and soft tissue manifestations (osteomas, epidermal cysts, lipomas, and soft tissue fibromatosis) has been designated Gardner syndrome. The association of adenomatous polyposis and a brain tumor (most commonly medulloblastoma, ependymoma, or anaplastic astrocytoma) is called Turcot syndrome.

Question 96

Metastatic tumors to the breast comprise ~1% of all tumors encountered in the breast. In adult women, what are the top 3 most common metastases to the breast?

Answer 96

Malignant melanoma, followed by lung and gynecologic cancers.

Question 97

Lymphomatoid granulomatosis most commonly presents as multiple pulmonary nodules. What are other common sites of involvement?

Answer 97

Brain, kidney, liver, and skin.

Question 98

Somatic activating mutations in BRAF, NRAS, or KIT are common and generally mutually exclusive in melanoma. Mutations in at least one of these genes can be found in ~__% of melanomas and each may render a patient eligible for systemic targeted therapy.

Answer 98

Somatic activating mutations in BRAF, NRAS, or KIT are common and generally mutually exclusive in melanoma. Mutations in at least one of these genes can be found in ~90% of melanomas and each may render a patient eligible for systemic targeted therapy.

Question 99

~50% of melanomas harbor activating mutations in BRAF. Mutations at codon 600, including V600E, V600_, V600_, and V600_, are likely to respond to BRAF-targeted agents such as vemurafenib and dabrafenib.

Answer 99

~50% of melanomas harbor activating mutations in BRAF. Mutations at codon 600, including V600E, V600K, V600D, and V600R, are likely to respond to BRAF-targeted agents such as vemurafenib and dabrafenib. Mutations outside of codon 600 should not be treated with a BRAF inhibitor.

Question 100

Why is testing for BRAF mutations in melanoma useful for treatment determination but not diagnostic purposes?

Answer 100

BRAF mutation occurs as high frequency in nevi and does not, therefore, distinguish benign melanocytic lesions from malignant.

Question 101

What are the six "classical" infectious childhood exanthems, and what are the causes?

Answer 101

First disease (Measles, Hard measles, 14-day measles, Rubeola, Morbilli) - Measles virus. Second disease (Scarlet fever, Scarlatina) - Streptococcus pyogenes. Third disease (Rubella, German measles, 3-day measles) - Rubella virus. Fourth disease (Staphylococcal scalded skin syndrome, Ritter's disease, Filatow-Dukes' disease) - Staphylococcus aureus. Fifth disease (Erythema infectiosum, slapped cheek disease) - Parvovirus (Erythrovirus) B19. Sixth disease (Roseola infantum, Exanthem subitum, 3-day fever, rose rash of infants, "sudden rash") - HHV6B or HHV7.

Question 102

What disease does HHV6 cause?

Answer 102

HHV6 is the etiologic agent of roseola infantum (sixth disease, exanthem subitum, 3-day fever, rose rash of infants, "sudden rash"). Fully-developed roseola manifests in 10% of those with acute HHV6 infection, with the remaining children displaying a nonspecific febrile illness. HHV6 is highly neurotropic and is one of the causes of viral encephalitis. Due to its combined propensity to produce fever and CNS infection, HHV6 is responsible for a significant proportion of childhood febrile seizures.

Question 103

What is the Kaposi sarcoma-associated herpes virus (KSHV)?

Answer 103

HHV8. It is associated with all clinical variants of Kaposi sarcoma, with primary effusion lymphoma, and the subset of multicentric Castleman disease seen in HIV+ patients. IHC for LANA-1 shows a characteristic speckled nuclear pattern in cells harboring KSHV.

Question 104

Ingested arsenic is excreted in urine, with most of the remainder distributed into ___, ___, and ___.

Answer 104

Ingested arsenic is excreted in urine, with most of the remainder distributed into skin, nails, and hair.

Question 105

What is the mechanism of arsenic toxicity, and what are clinical manifestations?

Answer 105

Arsenic inhibits the oxidative production of ATP. Thus, initial toxicity is manifested in dividing tissue such as GI mucosa, with nausea, vomiting, bloody diarrhea, and abdominal pain. The marrow is affected, causing cytopenias (with erythrocyte basophilic stippling similar to that seen in lead toxicity). Chronic toxicity results in peripheral neuropathy, nephropathy, skin hyperpigmentation and hyperkeratosis (particularly palms and soles) and transverse Mees lines in the nails.

Question 106

What are acrodynia and erethism?

Answer 106

Conditions that result from chronic exposure to mercury. Other names for acrodynia are hydrargyria, mercurialism, erythredema, erythredema polyneuropathy, Pink's disease, Bilderbeck's disease, Selter's disease, Swift's disease, Swift-Feer disease, and Feer syndrome. Another name for erethism is erethism mercurialis.

Question 107

What symptoms are seen in acrodynia (AKA hydrargyria, mercurialism, erythredema, erythredema polyneuropathy, Pink's disease, Bilderbeck's disease, Selter's disease, Swift's disease, Swift-Feer disease, and Feer syndrome)?

Answer 107

Acrodynia results from chronic exposure to mercury and occurs most often in infants and young children. Symptoms include irritability, photophobia, polyneuritis, autonomic manifestations (sweating, hemodynamic instability), and a desquamative erythematous rash on the palms and soles. It is associated with increased urinary catecholamines and can in many ways mimic pheochromocytoma. The presentation may also be similar to Kawasaki disease.

Question 108

Is Kaposi sarcoma always associated with HIV?

Answer 108

No. KS is the most common HIV-associated malignancy, leading to angiosarcomatous change of epithelial and mucous membrane-associated connective tissue. Although specifically due to the HHV8 virus, it is considered to be due to the convergence of immune evasion, oncogenesis, inflammation and angiogenesis. Although HHV8 was first detected in, and is usually associated with HIV+ patients, KS can be initiated through non-viral mechanisms, including iatrogenic immunosuppression and elevated expression of cytokines and angiogenic growth factors.

Question 109

What is epidermodysplasia verruciformis?

Answer 109

A rare condition with probable AR inheritance, characterized by the appearance of HPV-induced wart-like lesions early in childhood, with malignant transformation in ~50% of patients during adulthood, often in skin surfaces with sun exposure. Multiple HPV types have been isolated from these lesions, but HPV types 5 and 8 appear to have the most malignant potential in these individuals. It is associated with a gene locus on chromosome 17 which seems to impair defenses against several specific HPV types. Unlike other types of wart, EV does not appear to be transmissible by contact with healthy subjects. Lesions resembling EV are sometimes seen in organ transplant recipients.

Question 110

HPV __ has been associated with psoriasis and epidermodysplasia verruciformis.

Answer 110

HPV 5 has been associated with psoriasis and epidermodysplasia verruciformis.

Question 111

List premalignant penile lesions that have the capacity to evolve into invasive squamous cell carcinoma.

Answer 111

Condyloma acuminata. Erythroplasia of Queyrat. Bowen's disease. Bowenoid papulosis. Lichen sclerosis (AKA balanitis xerotica obliterans). Leukoplakia. Cutaneous horn. Pseudoepitheliomatous keratotic and micaceous balanitis (PKMB).

Question 112

What is Bowenoid papulosis?

Answer 112

A condition caused by HPV 16 that presents in younger males (but can occur in females) as multiple small pearly papules on the anogenital skin. Histologically, it resembles SCCIS, but rarely results in invasive carcinoma. While histologically difficult to distinguish from true SCCIS (Bowen disease and erythroplasia of Queyrat), it is usually easily distinguished clinically.

Question 113

What is a Buschke-Lowenstein tumor?

Answer 113

AKA giant condyloma (accuminatum) of Buschke and Lowenstein. Is a slow-growing, locally destructive verrucous plaque that typically appears on the penis but may occur elsewhere in the anogenital region. It most commonly is considered to be a regional variant of verrucous carcinoma, together with oral florid papillomatosis and epithelioma cuniculatum. It is commonly associated with HPV 6 or 11.

Question 114

What are some extrahepatic manifestations of HCV infection?

Answer 114

Hematologic diseases such as essential mixed cryoglobulinemia, lymphoma, and aplastic anemia. Renal disease, particularly membranoproliferative glomerulonephritis. Autoimmune disorders such as thyroiditis and the presence of autoantibodies. Dermatologic conditions such as porphyria cutanea tarda and lichen planus. Diabetes mellitus.

Question 115

What conditions are caused by mutations in the PTCH1/patched 1 gene?

Answer 115

More than 225 mutations in PTCH1 have been found to cause Gorlin syndrome/nevoid basal cell carcinoma syndrome. Somatic mutations are associated with sporadic basal cell carcinoma, medulloblastoma, breast cancer, colon cancer, and keratocystic odontogenic tumors. At least seven mutations in PTCH1 have been found to cause nonsyndromic holoprosencephaly.

Question 116

Eruptive xanthomas, Tendinous (tuberous) xanthomas. Xanthelasma. What are the patterns of elevation of TG and/or cholesterol for these entities?

Answer 116

Eruptive xanthomas, presenting as crops of yellow pruritic papulonodules, are seen with elevated TG (chylomicrons or VLDL). Tendinous (tuberous) xanthomas are seen near the knees or elbows and appear when there are simultaneous elevations in TG and cholesterol (elevated IDL). Xanthelasma are yellow periorbital papules that are associated with high cholesterol (LDL).

Question 117

Over 95% of T cells have TCR alpha-beta. A small percentage of TCRs composed of gamma and delta subunits. These are found in greatest number in what body locations?

Answer 117

Mucosal surfaces and skin.

Question 118

C1 esterase inhibitor (C1 Inh) deficiency is an autosomal dominant disorder also called hereditary angioedema. What parts of the body are affected?

Answer 118

Swelling is seen most consistently in the skin (upper extremity more than lower) and intestinal tract (abdominal pain episodes). Laryngeal edema, though classic and potentially lethal, is present in only about 1% of episodes but has a lifetime incidence of 50%. Facial swelling is rare, and while there is swelling of the soft palate and uvula, it spares the tongue. Acute episodes are treated with androgenic agents.

Question 119

What are the 2 main types of immunofluorescence tests for autoantibodies, and how are they performed?

Answer 119

Direct immunofluorescence (DIF) involves incubating cryostat sections of patient tissue with fluorescein-labeled AHG. Positive DIF tests confirm the in vivo presence of bound autoantibodies in the patient's tissues. Examples include skin IF and renal IF. Indirect immunofluorescence (IIF) involves incubating patient serum with cells/tissue known to contain specific antigens, then adding fluorescein-labeled AHG. Positive IIF tests confirm the presence of circulating autoantibodies.

Question 120

What is the clinical utility of anti-Jo1 antibodies?

Answer 120

Also called anti-tRNA synthetase. Implies high likelihood of developing interstitial lung disease in polymyositis/dermatomyositis.

Question 121

What is the clinical utility of anti-IF antibodies?

Answer 121

IF = intermediate filament. Polymyositis/dermatomyositis.

Question 122

What is the clinical utility of anti-PM1 antibodies?

Answer 122

Overlap syndrome with overlapping features of scleroderma and dermatomyositis.

Question 123

What are the 4 (plus one) types of hypersensvitiity reactions, their mediators, and associated diseases?

Answer 123

Type I (allergic, immediate-type): IgE; atopy, asthma, anaphylaxis. Type II (antibody-dependent, cytotoxic, antibody-mediated cellular cytotoxicity): IgM or IgG, complement, MAC; Goodpasture syndrome, autoimmune hemolytic anemia, erythroblastosis fetalis, rheumatic heart disease (also Graves disease and myasthenia gravis, but some classify these as type V). Type III (immune complex): IgG, complement, neutrophils; SLE, serum sickness, Arthus reaction, PSGN. Type IV (delayed-type, cell-mediated immune memory response, antibody-independent): T cells; tuberculin skin test, contact dermatitis, MS. Type V (an additional subtype sometimes used as a distinction from type II) (receptor mediated autoimmune disease): IgM or IgG, complement; Graves disease, myasthenia gravis.

Question 124

Pemphigus vulgaris, bullous pemphigoid, epidermolysis bullosa acquisita, dermatitis herpetiformis. All are autoimmune disorders, with the first resulting in suprabasal vesiculation and the other three resulting in subepithelial vesiculation. What is the antibody for each condition, how are they detected, and what is the pattern of reactivity?

Answer 124

Pemphigus vulgaris: anti-desmosomal; DIF on cryostat sections of skin results in chicken-wire IgG in epidermis. Bullous pemphigoid: anti-epithelial basement membrane/anti-hemidesmosome; DIF on cryostat sections of skin results in linear IgG along BM; in salt-split skin results in reactivity in roof. Epidermolysis bullosa acquisita: EBA Ag (? type VII collagen); DIF on cyrostat sections results in linear IgG along BM; in salt-split skin results in reactivity in floor. Dermatitis herpetiformis: gluten; DIF on cryostat sections of skin results in granular IgA especially in tips of dermal papillae.

Question 125

Bullous pemphigoid and epidermolysis bullosa acquisita both show linear IgG along the BM in DIF performed on cryostat sections of skin. How can they be differentiated?

Answer 125

In salt-split skin, BP has reactivity in roof, while EBA has reactivity in floor.

Question 126

Scleroderma (progressive systemic sclerosis) is associated with obliterative vasculopathy, dermal sclerosis, epidermal atrophy, tenosynovitis, esophageal sclerosis, interstitial lung disease, pulmonary hypertension, telangiectasia, calcinosis, and renal hypertension. What auto-antibodies are associated with scleroderma, and how are they detected?

Answer 126

ANA, anti-nucleolar, anti-Scl-70 (anti-topoisomeraseI). IIF on C. luciliae or HEp-2 cells; ELISA.

Question 127

Polymyositis/dermatomyositis is associated with proximal motor weakness and pain, heliotrope rash, Gottren syndrome papules, interstitial lung disease, possible internal malignancy. What auto-antibodies are associated with polymyositis/dermatomyositis and how are they detected?

Answer 127

Anti-Jo1 (tRNA synthetase). IIF on C. luciliae or HEp-2 cells; ELISA.

Question 128

Cutaneous meningioma. What are the 3 types?

Answer 128

Cutaneous meningioma is a rare tumor that most commonly occurs on the scalp and occurs in both congenital and acquired forms. The classification system divides cutaneous meningiomas into 3 types. Type I is the congenital type that is present at birth and generally occurs on the scalp and paravertebral regions. Type I tumors develop from ectopic arachnoid cells (meningothelial cells) that become trapped in the dermis and subcutis during development. This results from the failure of neural tube closure to completely trap all neural elements. Type II tumors consist of ectopic soft tissue meningiomas that extend to the skin by contiguity. These tend to occur around the eyes, ears, nose, and mouth. An important finding in this type of cutaneous meningioma is the lack of corresponding meningioma of the neuroaxis. Type III tumors are those that have extended into the dermis or subcutis from a primary meningioma that involves the neuroaxis (ie, a primary intracranial meningioma). Type III lesions are primary meningeal tumors that secondarily involve the skin by direct extension of underlying tumors through bone, traumatic defects, or surgical defects.

Question 129

Cutaneous meningioma. How do they present clinically? What are gross and microscopic appearances? What entities are in the DDx? IHC?

Answer 129

Clinically, cutaneous meningiomas present as firm painless subcutaneous nodules ranging in color from pallid to slightly dark. Lesions demonstrating both alopecia and hypertrichosis have been described. Grossly, lesions are solitary, firm, gray/white nodules. Microscopically, most primary lesions (type I) show meningothelial cells in nests and with psammoma bodies, as well as structures resembling psammoma bodies but lacking calcification (collagen bodies). Acquired lesions (types II and III) tend to have similar cytologic detail as congenital lesions but usually have less collagen, are more lobulated and cellular, and extend higher into the dermis. DDx for cutaneous meningioma is broad and includes nevus sebaceous, cyst, fibroma, glioma, hemangioma, lipoma, scar, verrucous hamartoma, and alopecia areata. IHC is positive for EMA and vimentin, and negative for keratins.

Question 130

What are the 3 most common metastatic tumors associated with granuloma formation in lymph nodes?

Answer 130

Squamous cell carcinoma, seminoma, and thymoma.

Question 131

Extracorporeal photopheresis, AKA extracorporeal photochemotherapy, AKA extracorporeal photoimmunotherapy. It is a leukopheresis-based therapeutic procedure. What is the one FDA indication for it?

Answer 131

Treatment of advanced cutaneous T cell lymphoma. But the procedure has been shown to have efficacy in the treatment of numerous other disorders, including GVHD, solid organ transplant rejection, scleroderma, lichen planus, atopic dermatitis, SLE, type 1 DM, and others.

Question 132

What genes are associated with susceptibility to basal cell carcinoma?

Answer 132

Loci associated with susceptibility to basal cell carcinoma have been identified on chromosome 1 (BCC1 and BCC2), 5 (BCC3), 12 (BCC4), 9 (BCC5), and 7 (BCC6). Mutations in the PTCH1 (chromosome 9), PTCH2 (chromosome 1), and SMO (chromosome 7) genes predispose patients to BCC. P53 (chromosome 17) gene may be involved in the development of sporadic BCC. Other possibly involved genes are the SUFU and MC1R genes.

Question 133

What is the histologic appearance of the lesions seen in Tularemia?

Answer 133

Abscesses containing nuclear dust and neutrophils. Bacteria are difficult to see, even with special stains such as Giemsa or Gram. Histiocytes surround the abscesses and are also seen in the walls of bronchi filled with pus. Venous thrombosis is common.

Question 134

DF and DFSP. Which one is CD34 positive?

Answer 134

DF is CD34 neg. DFSP lesional cells exhibit diffuse and strong CD34 expression.

Question 135

Merkel cell carcinoma. Epidemiology. Clinical presentation. Cell of origin.

Answer 135

MCC is a rare, highly aggressive neuroendocrine cutaneous neoplasm most commonly presenting in white males in their 7th or 8th decade of life. It has a nonspecific clinical appearance, most commonly presenting as a persistent asymptomatic red/pink cystic lesion, smaller than 2 cm, which rapidly increases in size over a period of weeks to months on chronically exposed, sun-damaged skin. Merkel cells are derived from the neuroectoderm and function as type I mechanoreceptors by forming synapselike contacts with the tactile hair discs of Pinkus. These cells are considered part of the diffuse neuroendocrine system or amine precursor uptake and decarboxylation system and are believed to originate from an asymmetric cell division of basal keratinocytes.

Question 136

Merkel cell carcinoma. Histologic appearance.

Answer 136

Histologically, MCC presents predominantly as a dermal-based lesion composed of strands or nests of uniform, small round cells with scanty cytoplasm, round to oval nucleus with powdery dispersed chromatin, and inconspicuous nucleoli. The tumor spreads to the reticular dermis and subcutis, generally sparing the papillary dermis, epidermis, and adnexa. Irregular nested groups of infiltrating cells with an Azzopardi effect, single-cell necrosis, frequent mitoses, vascular invasion, perineural invasion, and epidermal involvement via pagetoid spread may also be present. A desmoplastic response is often present in the surrounding dermis. The 3 histologic subtypes are intermediate, small cell, and trabecular variants. MCCs are unique in that they possess both neuroendocrine and epithelial features.

Question 137

Merkel cell carcinoma. IHC.

Answer 137

MCCs are unique in that they possess both neuroendocrine and epithelial features. They are positive for epithelial markers such as AE1/AE3, CAM 5.2, panCK, EMA, and Ber-EP4. Also, CK20 is a fairly specific and sensitive marker for MCC, with a characteristic paranuclear dotlike positivity. They are positive for neuroendocrine markers such as chromogranin, synaptophysin, NSE, neurofilaments, bombesin, somatostatin, VIP, and proconvertases PC1/PC3 and PC2. MCC may also express CD117, CD56, and rarely CD99 and TdT. MCC is negative for TTF-1, S100, and LCA.

Question 138

Merkel cell carcinoma. Genetic abnormalities.

Answer 138

Multiple chromosomal abnormalities have been found in MCC, the most common of which is the deletion of 1p36, a structural aberration found in up to 40% of MCCs. The pathogenesis is unclear may may involve MCPyV (Merkel Cell Polyoma Virus).

Question 139

DFSP cytogenetic abnormalities?

Answer 139

t(17;22)(q22/q13), resulting in a COL1A1-PDGFB fusion gene.

Question 140

Lafora body disease is a rare and severe form of progressive myoclonic epilepsy. This autosomal recessive disorder, with onset occurring between the ages of 10 and 18, is characterized by a course of generalized seizures followed by progressively worsening myoclonus, cognitive decline leading to dementia, and eventual death within 10 years. While the clinical course is distinctive, the diagnosis must usually be confirmed by demonstrating pathognomonic Lafora bodies, which are aggregates of polyglucosan, poorly constructed glycogen molecules with long strands that make them insoluble. What is the preferred method of diagnosis?

Answer 140

Skin biopsy is the preferred method for diagnosis, and shows PAS positive inclusions in peripheral cells of eccrine sweat ducts and within peripheral nerves.

Question 141

Germline mutations in what genes cause dyskeratosis congenita?

Answer 141

Germline mutations in TERT, TERC, DKC1, or TINF2 genes are seen in 50% of cases. All of these genes function in maintaining telomeres.

Question 142

What is the mode of inheritance of dyskeratosis congenita?

Answer 142

X-linked recessive when secondary to DKC1 mutations. Autosomal dominant when secondary to TERC or TINF2 mutations. Autosomal dominant or recessive when secondary to TERT mutations. Autosomal recessive when secondary to CTC1, WRAP53, NHP2, or NOP10 mutations.

Question 143

KIT mutations in melanoma are more common in acral lentiginous (11-38%), mucosal (6-19%), and sun-damaged skin (17%). The mutations are mostly in exon 11, with 34% being the ___ mutation.

Answer 143

KIT mutations in melanoma are more common in acral lentiginous (11-38%), mucosal (6-19%), and sun-damaged skin (17%). The mutations are mostly in exon 11, with 34% being the L576P mutation. This mutations confers sensitivity to tyrosine kinase inhibitors.