Skin Pathology Flashcards
1
Q
What is the most common pigmented lesion of childhood in lightly pigmented people?
A
Freckle
2
Q
What leads to a lentigo?
A
A localized melanocytic hyperplasia.
3
Q
What are nevus cells?
A
A form of a melanocyte - the pigment-producing cells that colonize the epidermis.
4
Q
Congenital melanocytic nevi are thought to represent what?
Most acquired melanocytic nevi are considered what?
A
Possible anomaly in embryogenesis.
Benign cellular aggregates.
5
Q
What is a dysplastic nevus?
A
A coalescent intradermal nest with cytologic atypia that may be a marker or precursor of melanoma.
6
Q
What is another term for “mole”?
A
Melanocytic nevus.
7
Q
Melanocytic nevi may arise due to what mutations in which pathway?
A
Mutations in the Ras pathway.
8
Q
What are seborrheic keratoses?
A
Common benign tumors found on the trunk of middle-aged or elderly patients.
9
Q
What is the gross morphology of seborrheic keratoses?
A
Superficial/flat and appear coin-like with waxy exophytic lesions. They may have a velvety surface.
10
Q
What mutation may be found in sporadic seborrheic keratoses?
In what other skin tumor might this mutation exist?
A
Activating mutation in FGFR3.
Acanthosis nigricans.
11
Q
What is the appearance of acanthosis nigricans?
A
Dark-thickened skin in creases or flexural areas with a velvety texture.
12
Q
What percent of acanthosis nigricans is benign vs. associated with malignancy?
A
80% benign.
- acquired: obesity, DM, pineal tumor, pituitary tumor, autoimmune endocrinopathy.
- inherited: rare, AD inheritance.
20% associated with malignancy: solid tumors, mostly GI carcinomas.
13
Q
What is another term for a fibroepithelial polyp?
A
“Skin tag”.
14
Q
What causes an epithelial inclusion cyst (wen)?
What is another name for it?
A
Invagination and cystic expansion of the epidermis, or from a hair follicle.
Sebaceous cyst.
15
Q
What are 5 examples of adnexal (appendage) tumors?
A
Eccrine poroma
Cylindroma
Syringoma
Sebaceous adenoma
Pilomatricoma
16
Q
Where do eccrine poromas occur?
A
Palms and soles - where sweat glands are numerous.
17
Q
What is a cylindroma?
What is a turban tumor?
A
An adnexal tumor with ductal differentiation on the forehead and scalp.
A turban tumor develops when there is coalescence of nodules with time that produces a hat-like growth.
18
Q
What are syringomas?
A
Lesions with eccrine differentiation, usually occurring in multiples near the eyelids.
19
Q
Sebaceous adenomas are association with which hereditary non-polyposis colorectal carcinoma syndrome?
A
Muir-Torre syndrome.
20
Q
What is actinic keratosis?
What is their appearance?
A
Areas of sun-damaged skin with hyperkeratosis. They may be a precursor to malignancy.
They are usually less than 1 cm. in diameter and are reddish-brown with a sandpaper-like consistency. Some lesions may even develop a “cutaneous horn”.
21
Q
Actinic keratosis associated with which mutations?
A
TP53 mutations.
22
Q
What are the 2 major associations with squamous cell carcinoma?
A
Sunlight exposure - UV radiation.
Immunosuppression - increases likelihood of infection with HPV-5 and HPV-8.
23
Q
What is epidermodysplasia verruciformis?
A
A rare AR condition with a high susceptibility to cutaneous squamous cell carcinoma due to infection with HPV-5 and HPV-8.
24
Q
What is xeroderma pigmentosum?
A
A genetic disorder in which there is a decreased ability to repair DNA damage such as that caused by UV light. It increases one’s risk for squamous cell carcinoma.
25
What is the "most common invasive cancer in humans"?
Basal cell carcinoma.
26
What is the course/aggressiveness of basal cell carcinoma?
What mutation is classically involved?
They are slow-growing that rarely metastasize. The are often recognized early and excised.
Constant activation of Hedgehog signaling.
27
What syndrome is associated with multiple basal cell carcinomas, (medulloblastomas or ovarian fibromas), odontogenic keratocysts and pits on palms/soles?
Gorlin syndrome (AKA nevoid basal cell carcinoma syndrome (NBCCS)).
28
What are the most common "driver" mutations in melanoma? (3)
Cell cycle control: CDKN2A gene (encodes p15, p16 and p14).
Pro-growth mutations: RAS and PI3K/AKT signaling.
Telomerase: TERT.
29
What is the gross appearance of melanoma?
What type of growth is noted?
They have variations in color and have irregular borders that are often notched.
Radial growth describes the horizontal spread of melanoma in epidermis and superficial dermis.
30
What is the ABCDE rule?
It is a guide to the usual signs of melanoma.
```
A - asymmetry.
B - border is irregular.
C - color is not uniform.
D - diameter > 6 mm.
E - evolving features.
```
31
What is the mnemonic for "painful" skin lesions?
GLENDAB
```
G - glomus tumor.
L - leiomyoma (angio-type).
E - eccrine spiradenoma.
N - neurofibroma.
D - dermatofibroma.
A - angiolipoma.
B - blue rubber bleb nevus.
```
32
What are the layers of the epidermis (superficial to deep)? (5)
"Come, let's get sun burned!"
```
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale
```
33
What is a dermatofibroma (benign fibrous histiocytoma)?
What often occurs prior to the development of this tumor?
A benign tumor found in adults and in the legs of young and middle-aged women. The lesion may be asymptomatic or tender and may change slightly in size over time.
Often preceded by trauma, which suggests an abnormal response to injury and inflammation.
34
What is dermatofibrosarcoma protuberans?
What is the hallmark genetic change?
A well-differentiated primary fibrosarcoma of the skin. They are slow-growing, but may be locally invasive, however they rarely metastasize.
A translocation involving the genes encoding colagen 1A1 (COL1A1) and platelet-derived growth factor-B (PDGFB).
35
What is mycosis fungoides?
When does it generally occur?
A type of cutaneous T-cell lymphoma that is usually confined to the skin for years, but potentially may evolve into a systemic lymhoma.
It can occur at any age, but most commonly in patients > 40 y/o.
36
What is the gross appearance of mycosis fungoides?
The proliferating cells are what type?
Scaly, red-brown patches with raised, scaling plaques which can be confused for psoriasis.
CD4+ T-cells.
37
On biospy you find Sezary-Lutzner cells and Pautrier microabscesses. What is the diagnosis?
Mycosis fungoides.
38
What is meant by "mastocytosis"?
A spectrum of rare disorders characterized by increased number of mast cells in the skin and other organs
39
What is urticaria pigmentosa?
A cutaneous form of mastocytosis that mostly affects children and accounts for >50% of cases.
40
What is "Darier sign"?
A localized area of dermal edema and erythema (wheal) that occurs when lesioned skin is rubbed.
41
What is dermatographism?
An area of dermal edema resembling a hive that occurs as a result of localized stroking of normal-looking skin with a pointed instrument (AKA "skin writing").
42
What symptoms are common in a patient with systemic mastocytosis? (3)
Pruritis and flushing due to environmental triggers.
Rhinorrhea.
Bone pain - osteoporosis due to excessive histamine release in the marrow microenvironment.
43
What kind of disorder is ichthyosis?
What causes it?
A disorder of epidermal maturation.
They are a group of inherited disorders associated with chronic, excessive keratin buildup (hyperkeratosis), which looks like fish scales.
44
What is the usual cause of urticaria (wheals/hives)?
Antigen-induced release of vasoactive mediators from mast cells
45
What microscopic changes are seen in acute inflammatory dermatoses?
Inflammatory infiltration, edema, and variable degrees of epidermal, vascular or subcutaneous injury.
46
What microscopic changes are seen in chronic inflammatory dermatoses?
Changes in epidermal growth (atrophy or hyperplasia) or dermal fibrosis.
47
What structure is implicated in the development of a wheal (hive)?
The dermis only - no epidermal involvement!
48
What are the 2 major causes of mast cell-independent, IgE-independent urticaria?
Exposure to chemicals or drugs - ASA, for example.
Hereditary angioneurotic edema - due to inherited C1 inhibitor deficiency.
49
What features characterize all types of eczematous dermatitis?
Red, papulovesicular oozing and crusted lesions that, if persistent, develop (1) acanthosis and (2) hyperkeratosis that produce raised scaling plaques.
50
Which feature characterizes acute eczematous dermatitis?
Epidermal spongiosis
51
Which immune cells are responsible for producing dermatitis?
T-cells
52
What is erythema multiforme?
Which 4 associations exist with it?
An uncommon self-limited hypersensitivity reaction.
1. Infectious etiologies: HSV, mycoplasma, histoplasmosis, coccidiomycosis, typhoid and leprosy.
2. Drug exposure: sulfa, PCN, barbiturates, salicylates, hydantoins and anti-malarials.
3. Cancers: carcinoma and lymphomas.
4. Collagen vascular diseases: SLE, dermatomyositis and PAN.
53
What is the pathogenesis is of erythema multiforme?
Keratinocyte injury mediated by skin-homing CD8+ cytotoxic T-cells.
54
What is Stevens-Johnson syndrome?
A febrile form of erythema multiforme which is most frequently seen in kids.
55
What is toxic epidermal necrolysis?
Diffuse necrosis and sloughing of cutaneous and mucosal epithelial surfaces - a variant of erythema multiforme.
56
How is psoriasis characterized?
Which symptoms may a patient notice?
It is a “chronic inflammatory dermatosis that appears to have an autoimmune basis”.
Commonly associated with arthritis (similar to RA) and onycholysis.
57
Which other conditions are associated with psoriasis? (3)
Myopathy
Enteropathy
AIDS
58
How is a psoriatic plaque characterized?
What is a common histologic feature?
Well-demarcated, pink to salmon-colored plaque covered by loosely adherent silver-white scale.
The stratum granulosum is thinned or absent and extensive overlying parakeratotic scaling is seen.
59
What is Auspitz sign?
What is Koebner phenomenon?
How is it treated?
Auspitz sign: in a psoriatic plaque there is abnormal arrangement of plaques in the dermal papillae which, when the scale is lifted from the plaque, produces multiple minute bleeding points.
Koebner phenomenon: the process by which local trauma sets in motion a local inflammatory response that becomes self-perpetuating.
-treatment with anti-TNF and anti-IL17 have shown efficacy.
They are both associated with psoriasis.
60
What is seborrheic dermatitis?
How is the name misleading?
A type of dermatitis that occurs at areas of with a high density of sebaceous glands, like the scalp, external auditory canal, retroauricular area, nasolabial folds and the presternal area.
It is a disease of inflammation of the epidermis, not necessarily of the sebaceous glands.
61
What are microscopic findings in seborrheic dermatitis?
Spongiotic dermatitis and acanthosis with parakeratotic mounds at the ostia of hair follicles (“follicular looping”) and mixed inflammatory cell populations.
62
What are the 2 disease associations with seborrheic dermatitis?
HIV with lows CD4+ counts
Parkinson disease
63
What is lichen planus?
What is the progression of it?
A disorder of skin and mucosa characterized by the 6 P’s: pruritic, purple, polygonal, planar, papules and plaques.
It is usually self-limited, most often resolving spontaneously 1-2 years after onset — resolution leads to post-inflammatory hyperpigmentation. Oral lesions may persist for years, however.
64
What is a rare complication of lichen planus?
What feature that is seen in psoriasis is also seen in lichen planus?
Squamous cell carcinoma in chronic mucosal and paramucosal lesions.
Koebner phenomenon.
65
What is pemphigus?
What age is most common to develop it?
What is the progression of it?
A blistering disorder caused by IgG autoantibodies against desmogleins that result in the dissolution of intracellular attachments within the epidermis and mucosal epithelium.
Most commonly in 4th to 6th decades.
It is most often benign, but in extreme cases it can be fatal without treatment.
66
What is the pathogenesis of bullous pemphigoid?
Which patients does it most commonly affect? Where does it occur?
Autoantibodies that bind proteins needed for adherence of basal keratinocytes to the basement membrane.
It most often affects the elderly; it is often seen on the forearms, axilla, groin and LE.
67
What malignancy is paraneoplstic pemphigus associated with?
Non-Hodgkin lymphoma.
68
What is the difference between the autoantibodies seen in pemphigus variants vs. bullous pemphigoid?
Pemphigus: IgG autoantibodies against intracellular adhesion components.
Bullous pemphigoid: IgG antibodies against desmosomal components of basal keratinocytes.
69
Where is the acanthosis located in the following:
Pemphigus foliaceus
Pemphigus vulgaris
Bullous pemphigoid
Pemphigus foliaceus - subcorneal.
Pemphigus vulgaris - suprabasal.
Bullous pemphigoid - subepidermal.
70
What features characterizes dermatitis herpetiformis?
Which patients does it most often affect?
Urticaria and grouped vesicles that are highly pruritic.
M > F; 3rd and 4th decades.
71
What is the pathogenesis of dermatitis herpetiformis? What aids in this detection?
What the a disease association?
Discontinuous granular IgA deposits that selectively localize in the tips of the dermal papillae, which is noted on direct immunofluorescence.
Celiac disease.
72
What is the “common feature” of epidermolysis bullosa?
What is unique about this process?
The common feature is a proclivity to form blisters at sites of pressure, rubbing or trauma at or shortly after birth; there are 4 subtypes.
The histologic changes are so subtle the EM may be needed to differentiate between the variants.
73
What is porphyria?
How are they classified?
What are the cutaneous manifestations of porphyria?
It is a group of uncommon inborn or acquired disturbances of porphyrin metabolism (they are pigments normally found in Hb, Mb and cytochromes).
They are classified based on their clinical and biochemical features.
Urticaria and vesicles associated with scarring, which is exacerbated by exposure to sunlight.
74
What is the pathogenesis of rosacea?
There is elevated levels of the antimicrobial peptide “cathelicidin”, which is involved in the cutaneous innate immune response. The elevated cathelicidin is alternatively processed by kallikrein-5.
75
What is most common form of panniculitis?
What are some features of this process?
Erythema nodosum (second most common is erythema induratum).
It presents as poorly defined, highly tender erythematous plaques and nodules more likely to palpated than seen. Fever and malaise may accompany the cutaneous signs.
76
What bacteria most often causes impetigo?
What is the gross and microscopic appearance?
Staph aureus.
A “honey-colored” crusted pustule with accumulation of neutrophils beneath the stratum corneum.
77
# Define the following:
```
Tinea capitis
Tinea barbae
Tinea corporis
Tinea cruris
Tinea pedis
Tinea versicolor
```
Tinea capitis: scalp; infants and adults.
Tinea barbae: beard; adult men.
Tinea corporis: superficial fungal infection in areas of heat and humidity.
Tinea cruris: inguinal region; obese men in warm weather.
Tinea pedis: athlete’s foot.
Tinea versicolor: upper trunk and has a highly distinctive appearance; caused by Malassezia furfur.
78
Which nevus variant carries an increased risk for melanoma?
Congenital nevus
79
Which nevus variant is often associated with fibrosis, is highly dendritic and heavily pigmented (black-blue nodule)?
Blue nevus
80
Which nevus variant is common in children and presents as a red-pink nodule, which is confused with hemangioma clinically?
Spindle and epithelioid cell nevus (Spitz nevus)
81
Which nevus variant is characterized as a lymphocytic infiltration surrounding nevus cells?
Halo nevus
82
What feature is paramount in malignant melanoma?
It is inherently immunogenic (contains inflammatory cells/infiltrate)!
83
What is the use of HMB-45?
In staining for melanoma.
84
4 benign epithelial tumors
Seborrheic keratoses
Acanthosis nigricans
Fibroepithelial polyp
Epithelial inclusion cyst
85
2 tumors of dermis
Dermatofibroma (benign fibrous histiocytoma)
Dermatofibrosarcoma protuberans
86
2 tumors of cellular migrants to the skin
Mycosis fungiodes (sutaneous T-cell lymphoma)
Mastocytosis
87
1 disorder of epidermal maturation
Ichthyosis
88
3 acute dermatoses
Urticaria (wheals/hives)
Acute eczematous dermatitis
Erythema multiforme
89
3 chronic dermatoses
Psoriasis
Seborrheic dermatitis
Lichen planus
90
3 inflammatory blistering disorders
Pemphigus
Bullous pemphigoid
Dermatitis herpetiformis
91
2 non-inflammatory blistering disorders
Epidermolysis bullosa
Porphyria
92
2 disorders of epidermal appendages
Acne vulgaris
Rosacea
