Dermatopathology #2 Flashcards
What’s the diagnosis? Note the calcified elastic fibers that look like snipped elastic bands.
Pseudoxanthoma elasticum
What’s the most likely diagnosis?
Pseudoxanthoma elasticum
What’s the diagnosis?
Ichthyosis vulgaris
*Note: usually orthokeratosis is associated with an increased granular layer. Ichthyosis vulgaris is the one exception to this rule.
**Note: usually parakeratosis is associated with an absent granular layer. Granular parakeratosis is the one exception to this rule.
What’s the most likely diagnosis? Note the compact orthokeratosis and greatly reduced granular layer.
Ichthyosis vulgaris
What genodermatosis could be represented in the image below?
Vesicular stage of Bloch-Sulzberger disease (incontinentia pigmenti)
*Note: mutation is in the NEMO gene (leads to defective activation of NF-KB)
What genodermatosis could be represented in the image below?
Incontinentia pigmenti (pigmented stage)
What’s the diagnosis? Note the polka-dot pattern of mastocytes.
Mastocytoma
What’s the diagnosis?
Mastocytoma
What cells are seen below?
Mast cells
What’s the diagnosis? What stain might be used to enhance the characteristic cells?
- Telangiectasia macularis eruptiva perstans (TMEP)
- Leder chloroacetate esterase stain (will stain mast cells even after they’ve degranulated)
*Image: Leder stain in TMEP
True or false: a Giemsa stain can be used to highlight mast cells in TMEP.
True
List a stain, other than a Leder stain or Giemsa stain, that can be used to highlight mast cells.
Toluidine blue; will stain mast cell granules metachromatically (i.e. the stain is blue, but the granules will stain purple)
*Note: this stain requires the presence of mast cell granules (i.e. the mast cells won’t stain if they’ve degranulated)
**Note: toluidine blue will also highlight mucin
In addition to mast cells, what other type of cells will a Leder stain highlight?
Myeloid cells (e.g. in leukemia cutis)
What’s the diagnosis? Note the spindled mast cells (a special stain would be required to identify these as mast cells since their morphology is so abnormal).
Telangiectasia macularis eruptiva perstans (TMEP)
This is a Leder stain. What’s the diagnosis?
Telangiectasia macularis eruptiva perstans
Name this histologic pattern. Note that this histologic pattern can be seen in a variety of conditions, including palmoplantar keratodermas and bullous congenital ichthyosiform erythroderma.
Epidermolytic hyperkeratosis
*Note: often this is seen in a solitary epidermolytic acanthoma (i.e. in addition to palmoplantar keratodermas and bullous congenital ichthyosiform erythroderma)
What are the four clinical (and histologic) variants of pyoderma gangrenosum?
- Ulcerative
- Pustular
- Bullous
- Vegetative
*Note: these are both clinical and histologic variants.
In this tumor there is a platelike growth of keratinocytes that runs parallel to the epidermis, with several points of attachment to the epidermis.
Tumor of the follicular infundibulum (infundibuloma)
True or false: P16 will be lost in melanoma.
True; p16 is a tumor suppressor gene that is often lost in melanoma (especially in some inherited forms of melanoma)
True or false: HMB-45 will be positive in a nevus, but only at the junctional component (it will decrease as the nevus cells mature towards the bottom of the nevus).
True
True or false: HMB-45 will be positive in a blue nevus, all the way down to the bottom of the lesion.
True
True or false: HMB-45 will be positive in melanoma, but negative in the deep parts of a nevus.
True; HMB-45 will be positive in melanoma and the junctional component of nevi, but will be negative in the deep parts of nevi
*Note: HMB-45 will be positive all the way to the bottom of a blue nevus
List four stains that can help you distinguish between a spindled melanoma and a spindled SCC (two stains that will be positive in SCC, but negative in melanoma, and two stains that will be positive in melanoma, but negative in SCC).
- Keratin 5.6 and P63; both of these will be positive in SCC and negative in melanoma
- S100, HMB-45, Melan-A, and MITF will all be positive in melanoma and negative in SCC
What’s the diagnosis?
Lichen sclerosus et atrophicus
*Note the “red, white, and blue sign”, with red hyperkeratosis, white papillary dermal edema, and a blue lymphoid band.
What’s the diagnosis?
Radiation induced dermatitis
*Note: the biopsy looks a lot like lichen sclerosus et atrophicus, but doesn’t have the lymphoid band. Also, adnexal structures are gone, and “radiation fibroblasts” may be seen at higher magnification.
What’s the diagnosis?
Radiation-induced dermatitis
What’s the most likely diagnosis? Note the rectangular biopsy, suggesting that the skin was rock hard.
Morphea
*Note: there are very little white spaces between the collagen fibers.
What’s the most likely diagnosis? Note the “trapped” eccrine coil.
Morphea
What’s the diagnosis?
Morphea
*Note: papillary dermal palor may be seen, like in lichen sclerosus et atrophicus (LSEA), but there is never a lyphoid band in morphea, like there often is in LSEA.
True or false: this biopsy could represent morphea.
True; lymphoplasmocytic infiltrates are common at the dermosubcutaneous junction in morphea
What’s the most likely diagnosis in this biopsy showing decreased CD34 staining?
Morphea
*Note: this is an early finding in morphea.
What’s the most likely diagnosis in this patient with peripheral eosinophila? Note the thickened fascia.
Eosinophilic fasciitis
What’s the diagnosis? Note that at higher magnification altered elastic fibers would be present within the tortuous channel in the epidermis.
Elastosis perforans serpiginosa (EPS)
*Begins in childhood or early adulthood, and 40% of cases are associated with a genetic disorder such as Down’s syndrome, Ehler-Danlos, Marfan’s syndrome, etc.
**Can occur secondary to penicillamine.
What’s the diagnosis? Note that collagen fibers are being eliminated.
Reactive perforating collaginosis (RPC)
*Begins during childhood after superficial trauma (Koebnerization), and usually involves the hands and arms.
**Tends to spontaneously resolve over 6-8 weeks.
What’s the diagnosis?
Scar
*Note: the fibroblasts run East-West, and the blood vessels run North-South
What’s the diagnosis in this previously traumatized skin?
Hypertrophic scar
What’s the diagnosis in this previously traumatized skin?
Keloid scar
What’s the diagnosis in this patient who smokes, and who has an extensive sun-exposure history.
Favre–Racouchot syndrome
*Note: smoking is thought to contribute to this disorder.
What’s the diagnosis in this biopsy of the ear?
Chondrodermatitis nodularis helicis
*Note: this is essentially a small decubitus pressure ulcer of the ear.
**Note: fibrin is typically present at the base of the ulcer, and granulation tissue is typically present adjacent to this.
What’s the diagnosis? What molecule is being deposited?
- Ochronosis
- Homogentisic acid
*Ochronosis is the connective tissue manifestation of alkaptonuria. In this condition, the urine turns a brown colour on exposure to air.
What’s “inherited ochronosis” called? What enzyme is deficient?
- Alkaptonuria
- Homogentisate 1,2-dioxygenase
What’s the diagnosis in this patient with an extensive history of sun exposure? Note the collagen that is beginning to look like amyloid.
Adult colloid milium
This condition occurs secondary to chronic lyme borreliosis. Name the condition and the infectious cause.
*Note: fat and large vessels are found close to the epidermis, due to a decrease in the thickness of the dermis.
- Acrodermatitis chronica atrophicans
- Borrelia afzelii (found in Europe, not America)
What’s the diagnosis in this patient with a chronic lyme borreliosis? Note the fat and eccrine coil that are very high in the biopsy, due to dermal atrophy.
Achrodermatitis chronica atrophicans
What’s the diagnosis in this biopsy from the back? Note the fingers of fat that are extending upwards to surround the adnexal structures.
Scleredema
*Note: mucin is pushing apart the normal collagen fibers (mucin may be removed during processing, but not always).
What’s the diagnosis in this biopsy from the shin? Note the attenuated collagen fibers that have been reduced to fine wisps.
Pretibial myxedema
*Almost always seen with Grave’s disease, but also reported with Hashimoto’s thyroiditis, primary hypothyroidism, and even euthyroidism.
What’s the diagnosis? Note the mucin deposition and fibroblast proliferation.
Scleromyxedema
*Marked proliferation of irregularly arranged fibroblasts, increased collagen, and diffuse deposits of mucin.
**Significance of monoclonal gammopathy is unknown.
What’s the diagnosis in this condition that closely resembles scleromyxedema histologically?
Nephrogenic systemic sclerosis
*Note: occurs in the context of renal failure, especially in patients who have received gadolinium enhanced MRI.
What’s the diagnosis in this biopsy containing mucin and inflammation surrounding the eccrine coil?
Tumid lupus
What condition is histologically indistinguishable from tumid lupus (and may in fact be a variant of tumid lupus)? This condition occur primarily on women’s chests.
Reticulated erythematous mucinosis
What’s the diagnosis? What would the diagnosis be if this biopsy were taken from an acral site?
- Focal mucinosis
- Digital myxoid cyst
What’s the diagnosis in this nodular condition? Note that plasma cells may be prominent in, and around, the nodule.
Nodular amyloidosis
*Note: may occur as a purely cutaneous condition, or in association with a primary systemic amyloidosis.
What’s the diagnosis in this patient with notalgia paresthetica? This biopsy was taken from the back.
Macular amyloidosis
*Note: the amyloid is epidermally derived (from dead keratinocytes that eventually turn into amyloid).
**Note: the amyloid is outlined by a fine network of melanophages.
What’s the diagnosis in this patient with lichen simplex chronicus of the lower leg?
Lichen amyloidosis
*Note: this condition occurs most commonly on the lower legs.
What’s the diagnosis in this patient with renal failure? What other disease is this condition associated with?
- Calciphylaxis
- Hyperparathyroidism
*Note: atherosclerosis will also cause calcification of blood vessels, but usually it’s just the large vessels that are involved.
What material is present in the accumulations of amyloid seen in nodular amyloidosis (i.e. what is deposited to create the amyloid)?
Immunoglobin light chains
What’s the diagnosis? Note that there are no shadow cells.
*Hint: this condition occurs most commonly on the necks or chins of 8-10 year olds. It can also occur on the heel of a newborn after a heel-stick.
Subepidermal calcified nodule
What’s the diagnosis in this scrotal biopsy?
Scrotal calcinosis
*Note: considered to be “idiopathic” by some, but may represent calcifications of epidermoid cysts.
**Note: the scrotum is one of the few places where smooth muscle will be present in the dermis, other than in vessel walls and erector pili muscles. The areola is the other site where this occurs.
What’s the diagnosis?
Gout
What’s the diagnosis? Note that the fissured material may stain with cystal violet, Congo red, and thioflavin, but will not stain with pagoda red.
Colloid milium
*Note: the fissured material is NOT amyloid, although it may stain with some amyloid stains (albeit weakly).
What’s the diagnosis in this patient with a ferrochelatase deficiency?
Erythropoietic protoporphyria
*Note: there’s massive reduplication of the blood vessels in the dermis.
What’s the diagnosis in this patient who does NOT have a ferrochelatase deficiency?
Lipoid proteinosis
*Note: there’s massive reduplication of the basement membrane surrounding blood vessels. This occurs more extensively than in erythropoietic protoporphyria (EPP).
What does anisotrichosis mean? In what condition is this finding seen?
- Variability in the diameter of follicles
- Androgenetic balding
True or false: there’s an increased anagen:telogen ratio in androgenetic alopecia.
False; there’s a decreased anagen:telogen ratio
True or false: in relapsing polychondritis, on DIF there’s “full-house” deposition of IgM, IgG, IgA, and C3 in the perichondrium.
True
True or false: neutrophilic eccrine hidradenitis (NEH) can sometimes occur before the diagnosis of leukemia.
True; usually NEH is associated with cytirabine therapy for AML, but occasionally it can occur before treatment begins. In these cases, it’s thought to represent a paraneoplastic phenomenon.
*Note: an idiopathic form of NEH can also occur in children, on the soles of the feet (idiopathic palmoplantar hidradenitis).
True or false: this likely represents an anagen follicle.
False; this likely represents a telogen follicle.
*Note: there’s trichilemmal keratinization that’s producing a “flame thrower” appearance. Also note the entrance of the sebaceous gland.
True or false: this is likely an anagen follicle.
True
True or false: in a catagen hair, there’s often an accordion-like folding of the outer root sheath, and multiple apoptotic cells.
True
What phase of the hair cycle is this hair in? Note the “flame thrower” appearance of the follicle, produced by the bright red trichilemmal keratinization.
Telogen (this appearance begins to develop during catagen though)
What are fibrous tract remnants?
Fibrous tissue that remains after the follicle moves upward in the skin during catagen and telogen (in anagen, the hair is located deeper in the dermis)
What’s the diagnosis? Note the wedge-shaped scar in the infundibular region of this biopsy (i.e. absence of elastic tissue on this Verhoeff Van Gieson stain).
Lichen planopilaris
*Note: the biopsy below shows a burnt out biopsy of LPP (no follicle visible).
What’s the most likely diagnosis?
Discoid LE
True or false: this could represent lupus panniculitis.
True
*Note the lipomembranous changes in the fat (“frost on a window pane”) which is often seen in lipodermatosclerosis.
What’s the diagnosis? At higher magnification, vacuolar interface dermatitis will be seen, but unlike in lupus, there is a “lymph in every hole”. Note the folliculotropism.
Mycosis fungoides (MF); a “lymph in every hole with folliculotropism” is always MF
True or false: lichen planopilaris (LPP) can produce either an interface dermatitis or a vaculoar interface dermatitis, while discoid LE (DLE) of the scalp can produce only an interface dermatitis.
False; it’s the other way around, where LPP can only produce an interface dermatitis, and DLE can produce either an interface dermatitis or a vacuolar interface dermatitis
What’s the diagnosis in this scalp biopsy, where multiple civatte bodies are all that remain of the hair follicle?
Lichen planopilaris
True or false: “bundling” of hairs into a single follicle is typical of alopecia areata.
False; it’s typical of scarring alopecias
True or false: this DIF is consistent with discoid lupus of the scalp.
False; it’s characteristic of lichen planopilaris, with the cytoid bodies being highlighted by IgM
True or false: “shaggy” linear fibrin is typical of lichen planopilaris on DIF.
True
True or false: this suppurative inflammation could be seen in folliculitis decalvans, acne keloidalis nuchae, or pseudopelade of Brocq.
False; Pseudopelade of Brocq is not suppurative, but folliculitis decalvans and acne keloidalis are
What’s the diagnosis? Note the anisotrichosis.
Androgenetic alopecia
True or false: a velus hair is one where the diameter of the hair is smaller than the inner root sheath.
True; this helps to distinguish them from miniaturized hairs in androgenetic alopecia
True or false: this could represent lichen planopilaris.
False; the inflammation here is peribulbar, and the diagnosis in this case is alopecia areata
True or false: alopecia areata is characterized by a “swarm of bees” (lymphocytes) around the hair bulb. However, eosinophils are also commonly seen.
True
True or false: pigment casts can be seen in both trichotillomania and alopecia areata.
True
True or false: many catagen hairs are seen in syphilis, alopecia areata, and trichotillomania; however, trichomalacia, when seen, is specific for trichotillomania.
True
In which two diseases can these findings be seen?
- Alopecia mucinosis
- Folliculotropic mycosis fungoides
What’s the diagnosis?
Acne
What’s the diagnosis from this occipital scalp biopsy? Note the suppurative folliculitis and extensive hypertrophic scarring.
Acne nuchae keloidalis
*Note the “naked” hair shafts.
What’s the diagnosis in this biopsy containing perifollicular epithelioid histiocytes at the level of the infundibulum? Note that at higher manification many of the histiocytes would have a reniform nucleus.
Langerhans cell histiocytosis
What’s the diagnosis?
Mycosis fungoides
What’s the diagnosis in this biopsy that shows mucin in the follicle and aytpical lymphocytes producing a vacuolar interface dermatitis?
Folliculotropic mycosis fungoides
What’s the diagnosis in this CD30+ lymphoproliferative disorder? Note the CD30+ Reed-Sternberg-like cells. Hint: this condition often presents with crops of recurrent ulcerated nodules and papules.
Lymphomatoid papulosis, type A
*Image: CD30+ stain.
True or false: anaplastic large cell lymphoma can only be distinguished clinically from lymphomatoid papulosis.
True
What are “bean bag” cells? In what condition are they seen?
Macrophages filled with karyorrhectic debris
Seen in subcutaneous panniculitis-like T-cell lymphoma (SPTCL), which at scanning magnification mimics a lobar panniculitis.
What’s the most likely diagnosis in this lymphoma that presented with deep indurated nodules and plaques? Note that at scanning magnification this condition mimics a lobar panniculitis.
Subcutaneous panniculitis-like T-cell lymphoma (SCTCL)
*Note: “bean-bag” cells are often seen (macrophages that have consumed karyorrhectic debris).
What’s the diagnosis in this disorder with no epidermotropism, a Grenz zone, blasts with finely dispersed chromatic, and cells that are CD3-, CD20-, and CD43-?
Myeloid leukemia
*Note: the patient should have a bone marrow biopsy.
What’s the diagnosis in this lymphoma that shows an “inverse” pattern of central darker reactive lymphocytes with surrounding neoplastic cells? Note that at scanning manification, epidermotropism would be absent. The neoplastic cells would be CD20+.
Marginal zone lymphoma
What’s the most likely type of lymphoma?
Marginal zone lymphoma
*Note: Bcl-6 and CD10 would normally stain a follicular center population.
What’s the most likely diagnosis in this lymphoma that’s BLC-6+, CD10-, and CD20+?
Primary cutaneous follicle center lymphoma
This is an example of diffuse large B-cell lymphoma, leg type. What population is primarily affected? Is the prognosis poor or excellent?
- Affects older patients (>70) and has a predilection for females
- Poor prognosis (5 year survival of 50%)
Is erythema nodosum a septal or lobular panniculitis?
Septal
What’s the most likely diagnosis? Note the interface dermatitis (which isn’t always present in this condition) in combination with necrosis of the fat lobule, and nodular lymphoid infiltrates.
Lupus panniculitis
Pancreatic panniculitis is a lobar panniculitis, but the fat lobules remain the same size, mimicing the appearance of a septal panniculitis. Why does this occur?
Because the lipocytes become calcified, stabilizing them, so that they don’t coalesce
What’s the diagnosis? Note that “ghost cells” are present, and that the lobar panniculitis is not evident due to deposition of calcium soap around the necrotic lipocytes.
Pancreatic panniculitis
What’s the diagnosis in this newborn patient? Note that the fat has solidified.
Subcutaneous fat necrosis of the newborn
*Note: the solidified fat and crystals provoke a granulomatous response.
What’s the diagnosis?
Subcutaneous fat necrosis of the newborn
True or false: subcutaneous fat necrosis of the newborn is histologically indistinguishable from steroid fat necrosis.
True
*Note: both crystal rosettes and granulomas are typically seen.
What’s the diagnosis? Hint: this type of panniculitis can be caused by various diseases.
Eosinophilic panniculitis
List four potential causes of eosinophilic panniculitis.
- Churg-Strauss
- Helminthic parasite
- Arthropod bite
- Hypereosinophilic syndrome
What’s the diagnosis in this patient with tuberculosis? Note the caseous necrosis.
Erythema induratum of Bazin
What’s the most likely diagnosis in this biopsy showing nodular neutrophilic vasculitis?
Nodular vasculitis (or erythema induratum of Bazin)
What’s the most likely infectious etiology for this caseous necrosis and Langhans giant cells?
Tuberculosis
What’s the most likely diagnosis in this panniculitide? Note the nodular angioplasia overlying the fat (fat not visible in the image).
Lipodermatosclerosis
*Note: there’s lipomembranous changes (“frost on the windowpanes”).
True or false: lipomembranous changes can be seen in any form of lobular panniculitis.
True; although it’s quite characteristic of lipodermatosclerosis
What’s the diagnosis?
Calciphylaxis
*Note: most commonly seen in patients with renal failure and resultant hyperparathyroidism.
What’s the diagnosis in this panniculitis-like condition? Note the “rimming” of the lipocytes with atypical lymphocytes.
Subcutaneous panniculitis-like lymphoma
What’s the diagnosis in this patient with panniculitis?
Cytophagic histiocytic panniculitis
*Note: the patient often dies from a hemorrhagic diathesis.
True or false: suppurative and granulomatous panniculitis is usually due to an infectious cause.
True; although this finding may also be due to a factitial disease
What’s the diagnosis?
Impetigo
What’s the diagnosis in this condition that is NOT an autoimmune blistering condition?
Bullous impetigo
What infectious agent is responsible for botryomycosis?
Most commonly Staphylococcus, but other bacteria, such as Pseudomonas, can also be responsible
*Note: abscesses and sinus tracts form, and clinically this may resemble a fungal mycetoma.
**Botryomycosis is one of three types of mycetoma (Madura foot), even though it’s caused by bacteria, and not a fungus. The other two types of mycetoma are actinomycotic mycetoma and eumycotic mycetoma.
What’s the diagnosis in a patient with this biopsy, and many abscesses and sinus tracts?
Botryomycosis
What’s the diagnosis in this condition caused by kytococcus sedentarius and corynebacterium?
Pitted keratolysis
What are the eponymously named clefts that occur at the dermoepidermal junction in very inflammatory LP?
Max Joseph spaces
What’s the diagnosis in this infectious condition that usually occurs in very sick patients?
Ecthyma gangrenosum
*Note: there’s a distinct lack of inflammatory cells around the vessel. The “blue haze” represent pseudomonas bacteria.
What’s the diagnosis in this condition that usually affects non-acral skin, and presents as sharply marginated erythema?
Erythrasma
What’s the diagnosis in this patient with a particular type of Klebsiella infection?
Rhinoscleroma
What are Russell bodies?
Plasma cells with cytoplasm that has been replaced by immunoglobin
*Note: these particular Russell bodies are seen in a biopsy of rhinoscleroma.
What’s the diagnosis in this patient with a painful ulcer on their genitals?
Chancroid
*Chancroid is caused by Haemophilus ducreyi.
True or false: tissue needs to be specially processed in order to visualize the organisms seen in granuloma inguinale.
*Note: Klebsiella granulomatis is the causative agent.
True; the tissue needs to be embedded in plastic, and then cut very thin (about 1 micron in thickness, while typical sections are 3-6 microns in thickness)
What’s the diagnosis?
*Note: globi represent a certain type of bacteria.
Leprosy
*Note: globi represent mycobacterium leprae.
*Image: note the rod-like organisms within the globi.
What type of leprosy is seen below?
Tuberculoid leprosy
*Note: epitheliod granulomas are seen running East-West in the dermis (“lavender sausages”).
In which situations are erythema nodosum leprosum commonly seen? List two situations.
- Pregnant patients unaware of their diagnosis
- Patients being treated for their leprosy
What’s the most likely infectious cause?
Tuberculosis
List two unique features of plasma cells that might help you to distinguish them?
Perinuclear Hoff and clockface nucleus
What’s the infectious cause of this condition? Hint: note the long “slender”, “sexy”, rete ridges.
Treponema pallidum causes syphilis
What’s the most likely cause of this condition, where endothelial swelling has obscured the vessel lumen? Hint: plasma cells are seen in 2/3 of cases, and neutrophils are commonly seen in the stratum corneum.
Syphilis
What’s the name of this condition, caused by Borrelia afzelii? Hint: this condition is also known as Herxheimer disease.
Acrodermatitis chronica atrophicans
What’s the diagnosis in this condition in which organisms tend to line up at the periphery of vacuoles like the bulbs on an old-fashioned mirror, or the bulbs at an old-fashioned movie theatre (“Marquis sign”)?
Leishmaniasis
What’s the diagnosis in this infectious process? Note the compact stratum corneum just above the granular layer.
Bullous tinea
What’s the diagnosis? Note the large spherules with gray lacy and granular cytoplasm.
Coccidiomycosis
True or false: endosporulation is necessary to establish the diagnosis of coccidiomycosis.
False; endosporulation may be present, but is not necesary to establish the diagnosis of coccidiomycosis
What’s the diagnosis? Note the groups of organisms clumped together in “gelatinous condominiums” (i.e. not in “single family housing”).
Cryptococcus
*Note: the yeast organisms will be pleomorphic, and will vary markedly in size and shape.
What’s the diagnosis in this fungal disease? Note the melanin in the fungal walls, highlighted here with a Fontana-Masson stain.
Cryptococcosis
What’s the diagnosis in this fungal disease? Hint: organisms will tend to be few in number, usually with giant cells that are uniform in size and shape.
Blastomycosis
What’s the diagnosis? Note the presence of a thick-walled organism, with an asymmetric appearance (i.e. one side of the cell wall is much thicker than the other side).
Blastomycosis
*Note: the organisms tend to be found within giant cells.
What’s the diagnosis in this fungal disease, seen below with a Grocott’s methenamine silver stain? Note the narrow-based “mariner’s wheel” budding.
Paracoccidioides (South American “blastomycosis”)
*Note: Paracoccidioides braziliensis lacks the thick refractile wall and eccentric nucleus of Blastomyces dermatitidis.
What’s the diagnosis? Note the small uniform dots within histiocytes, each surrounded by a pseudocapsule.
Histoplasmosis
True or false: lobomycosis (keloidal blastomycosis) has a characteristic “pop-bead” chain appearance.
True
*The organism is lacazia loboi
What is the most likely diagnosis in this PAS stain showing rare cigar-shaped yeasts?
Sporotrichosis
True or false: this could represent a mycetoma.
True
*Note: the fungal elements will be visible within a true fungal mycetoma.
What is the bright pink material responsible for the Splendore-Heoppli phenomenon?
Club-shaped accumulations of immunoglobin
*The Splendore-Hoeppli phenomenon also refers to asteroid body formation.
What population tends to be most affected by epithelioid sarcoma? Where do the lesions most commonly occur?
- Young people (between ages 20 - 40 usually)
- On the extremities
What’s the diagnosis?
Chromomycosis
What’s it called when pigmented hyphae are seen in the tissue, and a “cystic” structure forms (a cavity surrounded by histiocytes)? Note that this diagnosis can be caused by a wide variety of fungal species.
Phaeohyphomycosis
*Note: this is often caused by traumatic implantation of fungus.
True or false: this could be mucormycosis or a rhizopus infection.
True
*Note: lumpy bumpy refractile hyphae will be seen.
True or false: this could represent an aspergillus infection. Hint: note the delicate hyphae and bubbly blue cytoplasm.
True
*Note: contrast this to the hyphae of mucormucosis or rhizopus, which are bright red. See the image below for comparison (rhizopus).
True or false: this could be an aspergillus infection.
True
What’s the diagnosis?
Rhinosporidosis
What’s the diagnosis?
Viral wart
What’s the diagnosis?
Myrmecia wart
What’s the diagnosis?
Flat wart
*Note the koilocytes under the granular layer.
What’s the diagnosis?
Viral changes (at scanning magnification the diagnosis of a flat wart would be more obvious)
What’s the diagnosis?
Viral induced changes (these are occuring in a condyloma)
This is a cyst of some sort that has been infected by a viral wart, thus the lining of the cyst will look like a wart.
Here’s the lining of the cyst closer up!
What’s the diagnosis in this lesion induced by HPV? Note the hyperchromatic nuclei indicative of cytologic atypica.
Bowenoid papulosis
*Note: condyloma accuminata are also caused by HPV, but a bowenoid papulosis is on its way to becoming Bowen’s disease (SCC in-situ) thanks to this virus.
This is a biopsy from the mouth showing focal epithelial hyperplasia of the mouth. What infectious etiology is involved? What’s the eponymous name for this condition?
- HPV 13 or 32 infection
- Heck’s disease
What’s the diagnosis in this infectious disease? Note the acantholysis and ballooning degeneration of keratinocytes.
HSV infection
What’s the diagnosis? Note the very characteristic nuclear cytopathic effect of “eggshell” chromatin at the periphery of the cells.
HSV infection
What’s the diagnosis? Note the prominent nuclear moulding and “eggshell” chromatin.
HSV infection
What infection could be responsible for this “owl’s eye” nucleus?
CMV
What’s the diagnosis?
Molluscum contagiosum
What’s the diagnosis?
Deep molluscum contagiosum (the lesion does not connect with the surface of the skin)
True or false: molluscum bodies can be seen on Tzank smear.
True
True or false: many viral infections can produce reticular degeneration on histology.
True; this finding is non-specific
True or false: flat worms aren’t able to poo.
True; they have to calcify their waste in the form of calcareous bodies
What’s the diagnosis?
Round worms
*Note: this is an onchocerca microfilaria (baby onchocerciasis round worm).
True or false: these atypical CD30+ lymphocytes could be occuring in the context of an arthropod bite.
True! In fully “mature” bug bites, atypical lymphocytes with CD30+ are often present
What’s the diagnosis?
Scabies
What are the feces of scabies called?
Scybala
What’s the diagnosis?
Scabies
*Note: the scabies organisms like to snack on the granular layer, thus they will be found just above the stratum granulosum.
True or false: this could be a botfly. Note the large size of the organism.
True
*Note: there is well developed muscle and a thick chitinous layer.
**Botfly is dermatobia hominis.
What’s the diagnosis in this biopsy from the toe of a patient who was recently walking along a beach in a tropical place? Hint: this is caused by the jigger flea (chigoe flea).
Tunga penetrans (chigoe flea, jigger flea); these organisms cause tungiasis
