Dermatopathology Flashcards by Emily Prazak

Describe vitiligo

Partial or complete loss of melanocytes

Well demarcated macules/patches

Hand/wrist, axillae, perioral/periorbital, anogenital

Pathogenesis: autoimmune

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What is albinism caused by?

it’s usually an inherited defect in tyrosinase

there is no melanin produced

in contrast to vitiligo, there are normal melanocytes in albinism, there just isn’t the enzyme necessary for normal function

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What are the two general causes of pigmented lesions?

excess melanin
increased number of melanocytes

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What are three examples of pigmented lesions due to excess melanin?

freckle

melasma

solar lentigo

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What are two examples of pigmented lesions due to increased number of melanocytes?

melanocyte hyperplasia - lentigo simplex

melanocytic neoplasis - nevi, melanoma

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What is the technical term for a freckle?

ephelis

ephelides

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Under histology, what do freckles look like?

increased pigment in basal melanocytes

normal number of melanocytes

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Describe melasma.

it’s mask-like hyperpigmentaiton on forehead and cheeks due to increased pigment transfer from melanocytes to keratinocytes

occurs in pregnancy or oral contraceptive use

usually will resolve

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WHat is a solar lentigo?

a hyperpigmentation of the basal epidermis due to excess melanin production

it occurs in the elderly in areas of heavy sun exposure - it’s a protective mechanisms of the melanocytes

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Describe lentigo simplex.

it’s localized hyperplasis of melanocytes

it can occur in all ages and isn’t related to sun

you get small brown macules anywhere on the skin

it results from increased number of melanocytes, resulting in increased pigment in stratum ocrneum and basal epidermis\

ITS AN EXAMPLE OF MELANOCYTIC HYPERPLASIA

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In terms of skin neoplasia, what is a benign neoplasia and a malignant neoplasia

a benign neoplasm has no capability for metastasis - this includes those neoplasia that look like they COULD become metastatic, but haven’t crossed the basement membrane yet

malignant neoplasma have the potential for metastasis and have crossed the basement membrane

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Is squamous cell carinoma in situ melignant or benign?

it’s still considered benign because it hasn’t crossed the basement membrane

this means it’s NOT CANCER

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What are some benign neoplasia of the skin?

Melanocytic: Nevi

Epithelial: AK, adenomas

Stromal: leiomyoma, hemangioma

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What are some malignant neoplasia of the skin?

Melanocytic: Melanoma

Epithelial: SCC, BCC

Stromal: DFSP, leiomyosarcoma, angiosarcoma

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What are the 3 lifes stages of a nevi?

junctional (at the junction of the epidermis and dermis - but not in the dermis yet)
compound (in both epidermis and dermis)
dermal (loss of the junctional part and only in the dermis)

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WHat is the msot common mutatoin in a nevi?

BRAF

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What’s the clinical treatment for a spitz nevus?

you have to take the whole thing off whenever you get path report saying its a spitz because they’re very hard to predict and it’s better to just remove the whole thing

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Why do blue nevi look blue?

the pigmentation is deeper than in other nevi, so through the Tyndall effect and light scattering properties, they end up looking dark blue in color

they are dermal proliferations of spindled melanocytes

totally benign

WHat is a nevus of Ota

What is a nevus of Ito?

Ota - peri-ocular or intraocular dermal melanocytic nevus

ito - “mongolian spot” which is the same type of lesion as the Ota, just on the skin and not the eye

How are dysplastic nevi graded?

a pathologist will grade them based on the severity of dysplasia - how atypical they are

mild, moderate, and severe

you should excise those of moderate or severe atypia

people with multiple of these have an increased risk of melanoma

What is the only reliable way to exclude melanoma from a DD?

biopsy and get a path report

WHat are the 2 growth patterns of melanoma?

radial growth (in situ): just superficial and cannot metastasize

vertical growth: dermal invasion, formation of nodule - potential to metastasize

What gives melanoma its color variation?

a melanoma likes to spread up into the stratum corneum, but it won’t do so uniformaly, so the pigment is at varying layer sin different areas of the melanoma

What is the best predictor of a melanoma’s probability to metastasize?

breslow depth!!!!!

less than 1 mm - unlikely to metastasize

the higher the depth of penetration, the greater the liklihood of metastasis - that’s why they do a sentinel LN biopsy for melanomas with breslow depth of over 1 mm

What are some other prognistic indicators of melanoma metastasis besides breslow depth?

ulceration - more likely to metastasize increased mitotic rate - depends on mutations clark level (less accurate breslow)

What is a seborrheic keratosis?

it's a very common epithelial neoplasm, typically found on the trunk, head and neck they are brown and velvety papules/plaques, well demarcated proliferation of keratinocytes that are pigmented - often confused for nevi or melanoma Many on elderly patients solar lentigo can grow into these they cause super thick epidermis with horn cysts

What is an epithelial cst? WHat is it usually filled with?

they are down growths of epidermis which become cystic and filled with keratin they can be subcutaneous or dermal they rupture easily and become inflamed

What is an actinic keratosis?

it's a benign neoplasm of epidermis (that may precede SCC) it's induced by sunlight, ionizing radiation or hydrocarbons it's a rough spot on the skin - especially sun exposed skin It's a form of hyperkeratosis at the basal layer

What is the treatment for actinic keratosis?

because some will progrss to squamous cell carcinoma if untreated, thy are usually treated with liquid nitrogen

What is squamous cell carcinoma?

a neoplasm of squamous cells in the skin in situ - technically not cancer yet SCC - has crossed the basement membrane, but only 5% will actually metastasize mostly on elders with sun exposure

Histologically, what is the difference between an actinic keratosis and SCC?

in AK, the atypical cells are still lined up along the basement membrane In SCC, the atypical cells have progressed and moved upward to replace the entire epidermis

What does a basal cell carcinoma typically look like?

a pearly papule with telengiectasia they rarely metastasize it's the most comon human malignancy - all sun related

Adnexal neoplasms of the skin can be a clue to internal pathology, with these two syndromes as examples....

Cowden's syndrome Muir Torre syndrome

What is Cowden's syndrome?

it's a hereditary condition with a mutation in PTEN, making one prone to multiple hamartomas and malignancies The patient will most oftne present with multiple trichilemmomas on the base (which are benign keratoses on acral skin) while the skin ones are bening, they probably have internal carcinaoms of the breast, endometrium, and thyroid, also the cerebellar lesions

What is a trichilemmoma?

benign proliferation of hair follicle epithelial - suggestive of Cowden's syndrome

WHat is a sebaceous hyperplasia?

it's an acquired, localized icnrease in sebaceous glands - they will be larger than normal it's not neoplastic they are common on the face look like a yellow papule

What is Muir-Torre Syndrome?

it's a hereditary germline mutation in DNA mistmatch repair proteins (MLH1 and MSH2) patients will present with sebaceous adenoma and carcinoma and keratoacanthomas Internally they will often have colon/rectlal, endometrial, and ovarian carcinaoms it's a subset of hereditary non-polyposis colorectal carcinoma syndrome

What is a dermatofibroma?

they are entirely benign dermal proliferation of histiocytes and fibroblasts they are tan, brown, firm papules commonly on the legs test with the pinch test - they'll dimple

Where would you want to bipsy a rash?

non-ulcerated/intact skin - usually sample the center and the edge

What is the main thing to think about when biopsying discrete lesions?

how deep does it go?! the biopsy needs to be representative in horisontal and vertical axis

When would you do a shave biopsy? When would you do a punch biopsy?

shave for superficial lesions like BCC, AK, SCC in situ, pigmented macules. because it's better cosmetics and you don't need to stitch do a punch for neoplasms involving the dermis (like nodular BCC, SCC\< melanoma, etc. and most rashes), These require sutues.

What's the difference between an incisional and excisional biopsy?

an incisional doesn't include the entire lesion (punch is an example) and excisional does