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SBL Final > Dermatopathology (Part 1 of 4) > Flashcards

Dermatopathology (Part 1 of 4) Flashcards

1
Q

what is the most common pigmented lesion of childhood?

A

freckles

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2
Q

when and where are freckles seen?

A

after sun exposure and in sun exposed areas

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3
Q

how do freckles change over time?

A

they fade and darken with season changes–> change in the degree of pigmentation

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4
Q

what is hyperpigmentation?

A

an increase in melanin pigment in basal keratinocytes

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5
Q

if you are seeing freckle like lesions in non-sun exposed areas, what might you be seeing?

A

cafe au lait spots

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6
Q

how are cafe au lait spots in neurofibromatosis different from freckles?

A

they are larger and arise independently of sun exposure; they contain aggregated melanosomes (macromalanosomes) in the cytoplasm of their melanocytes

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7
Q

what are malanocytes derived from?

A

NCCs

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8
Q

what is lentigo?

A

a benign localized hyperplasia of melanocytes–> no sex or racial predilection; cause unknown

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9
Q

when are lentigo’s initiated?

A

in infancy and childhood

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10
Q

how would you describe the morphological features of a lentigo?

A

5-10 mm, oval, tan-brown macules or patches

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11
Q

what happens to lentigos when they are exposed to sunlight?

A

nothing- they do not darken

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12
Q

what does a lentigo look like histologically?

A

linear (nonnested) melanocytic hyperplasia

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13
Q

where are lentigos restricted to?

A

restricted to the cell layer immediately above the basement membrane

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14
Q

what are acral sites?

A

palms and soles of the feet

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15
Q

what is the colloquial term for a melanocytic nevus?

A

a mole

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16
Q

how are melanocytic nevi acquired?

A

by activating mutations in components of the RAS or BRAF signaling pathway–> limited period of proliferation

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17
Q

what causes the proliferation seen in a melanocytic nevus to be in a permanent growth arrest?

A

a disruption to the p16/INK4a

18
Q

what is the p16/INK4a’s function normally?

A

it inhibits CDK4 and CDK6

19
Q

how would you describe the morphological features of a melanocytic nevus?

A

usually less than 6 mm, tan-brown, and uniformly pigmented; flat macules or elevated papules with well-defined borders

20
Q

what are the earliest melanocytic nevi lesions known to be?

A

junctional nevi

21
Q

what are junctional nevi?

A

aggregates or nests of round cells that grow along the dermoepidermal junction

22
Q

what could junctional nevi progress to?

A

compound nevi

23
Q

what are compound nevi?

A

nests or cords that grow into the underlying dermis (nests are in the epidermis and the dermis)

24
Q

what can compound nevi progress to?

A

intradermal nevi

25
Q

what are intradermal nevi?

A

there are no epidermal nests, and they are usually older lesions

26
Q

which benign melanocytic nevi has the most melanin?

A

the more superficial one

27
Q

what does the deepest evidence of a benign melanocytic nevus look like?

A

fusiform–> fascicles resembling neural tissue–> neurotization

28
Q

what is helpful when trying to differentiate between a benign nevi and melanoma?

A

the metamorphosis of the nevi into something that resembles neural tissue in benign nevi

29
Q

which nevi are often more elevated?

A

compound and dermal

30
Q

which nevi are nice and flat?

A

junctional

31
Q

what are the diagnostic architectural features of a dysplastic nevus?

A

coalescent intraepidermal nests

32
Q

what are the cytologic features of a dysplastic nevus?

A

cytologic atypia

33
Q

what is the clinical significance of a dysplastic nevus?

A

it is a potential marker or precursor of melanoma

34
Q

what is dysplastic nevus syndrome?

A

an autosomal dominant disorder that may cause development of several melanomas at multiple sites

35
Q

what gene is involved in dysplastic nevus syndrome?

A

CDKN2A or CDK4 gene

36
Q

dysplastic nevi often acquire activating mutations in what genes?

A

NRAS and BRAF genes

37
Q

what are the histological features of dysplastic nevi?

A

they are larger than acquired nevi, >5mm–> could be hundreds; variegated pigmentation, irregular borders of lesions

38
Q

what are the atypical features seen in dysplastic nevi?

A

large nuclei, irregular angulated nuclear contour, and hyperchromasia

39
Q

microscopically, dysplastic nevi usually involve what?

A

both the epidermis and the dermis

40
Q

what is the most deadly of all skin cancers?

A

melanoma

41
Q

what is melanoma strongly linked to?

A

acquired mutations caused by exposure to UV radiation in sunlight (DNA damage)

42
Q

the increased incidence by decrease in death rates of melanoma may reflect what?

A

the effectiveness of immune checkpoint inhibitor therapy

SBL Final (21 decks)

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