Disorders of Pigmentation and Melanocytes Flashcards Preview

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Flashcards in Disorders of Pigmentation and Melanocytes Deck (62):
1

What is vitiligo?

An acquired loss of pigmentation due to inflammatory destruction of melanocytes.

2

Who most commonly gets vitiligo?

Affects all races, however, it is most problematic in dark skinned patients.

3

What is the average age of onset of vitiligo?

20 years

4

What happens in histology of vitiligo?

Melanocytes are missing.

5

What is melasma?

Symmetrical hyperpigmented patches. Usually on the face and affects women with pigmented skin.

6

What causes melasma?

Hyperfunctioning melanocytes reacting to sun

7

What is post inflammatory pigment alteration?

Occurs after a variety of inflammatory and traumatic processes.

8

What does colour of post inflammatory pigment alteration depend on?

Colour depends on complex interplay of factors

9

What does histology show on post inflammatory pigment alteration?

Melanophages in superficial dermis

10

What is ephelis?

Freckles

11

What triggers formation of ephelis/freckles?

Wax and wane with sun exposure

12

What does histology show with ephelis?

Normal epidermal architecture with increased keratinocyte pigmentation.

13

What is lentigo simplex?

Small flat darkly pigmented macule

14

What comes in fewer numbers ephelides or lentigo simplex?

Lentigo come in fewer numbers and are more darkly pigmented

15

What type of proliferation is lentigo simplex?

It is a melanocytic proliferation

16

What other growth is lentigo simplex similar to?

Junctional melanocytic naevus

17

What are the important histological features of lentigo simplex?

They live in the basal layer of the epidermis

They live as single cells (this differentiates them from melanocytic naevus)

They have an increased number of melanocytes

18

What are the clinical features of benign melanocytic naevus?

Small

Well circumscribed

Even colouration

19

What are the histological features of common benign melanocytic naevus?

Symmetrical

Cells predominantly in nests

Round to oval, even nuclei

Maturation as the cells get deeper

Classified as junctional, compound, and intradermal

20

How are benign melanocytic naevi distinguished from malignant growths?

Architectural features (Benign = cells predominantly in nests, malignant = cells grow individually and more disordered)

Cytological features (Nuclei that are crowded/overlapping, bigger than they should be, and pleiomorphic)

In naevi cells get more mature the deeper into the growth you go.

21

What is a spitz naevus?

A benign lesion that looks a lot like a melanoma and histologically looks like a melanoma

22

Which demographic commonly gets a spitz naevus?

Children and young adults

23

What is a blue naevus?

A dermally based benign lesion that is comprised of dendritic melanocytes

24

What are the melanomas that look like spitz naevi called?

Spitz melanomas

25

What are congenital naevi?

Large, uncommon manifestation of congenital naevi

26

What are the issues associated with congenital naevi?

They may present significant cosmetic problems

They run a risk of developing into proliferative nodules and melanomas.

27

What are dysplastic naevi?

Controversial naevi that are larger than benign naevi (>6mm) with irregular borders and variable colouration.

28

Is the risk of dysplastic naevus becoming a melanoma high?

No, however in people that have many of them there is a higher chance of developing a melanoma especially if there is also a family history

29

What do dysplastic naevi look like?

Less symmetrical than benign naevi

More single cell growth

Some larger, darker nuclei

Fibrosis in upper dermis

Cytological atypia

30

What is done to dysplastic naevi?

Despite low risk of melanoma formation they are excised.

31

What is a melanoma?

Malignant tumour derived from melanocytes

32

Does a melanoma show up only in skin?

No, it can rarely show up in other organs.

33

How common is melanoma?

4th most common cancer in Australia.

1/14 males and 1/23 females are expected to develop melanoma in their lifetimes.

34

What is the survival rate of melanoma?

96% after 5 years if caught early

63% if there is local spread

34% if there is metastatic spread

35

What are the risk factors for melanoma?

Strongest:

Family history

Large numbers of benign or atypical naevi

Previous melanoma

Others:

Immunosuppression

Sun sensitivity

Exposure to UV radiation

36

How is melanoma diagnosed?

ABCDE

Asymmetrical

Border irregularity

Colour variability

Diameter >6mm

Evolving

37

What are the microscopic features of melanoma?

Large

Asymmetrical

Poorly circumscribed

Single cells predominate over nests

Growth in continuity from one rete ridge to another

Extension into upper levels of epidermis

38

What is "buckshot" scatter?

Scatter of cells into epidermal ridges

39

What cytological atypia are seen in melanomas?

Nuclear enalrgement

Hyperchromasia

Irregularity

Prominent nucleoli

40

What is a melanoma in situ? How likely is it to metastasize?

Growth within the epidermis.

It lacks metastatic potential
until it grows out of the epidermis (no blood vessels in epidermis)

41

What is the radial growth phase of a melanoma? How likely is it to metastasize at this stage?

Refers to growth within epidermis as well as microinvasion into the superficial dermis. Also lacks metastatic potential.

42

What is the vertical growth phase of a melanoma? How likely is it to metastasize at this stage?

Invasive melanoma within the dermis that is larger than the epidermal nests. Contains mitotic figures.

This stage implies a capacity for metastatic spread.

43

What are the microscopic prognostic indicators for melanomas? Which factor is most important?

Tumour thickness (Breslow thickness)

Level of invasion

Ulceration

Mitotic rate

Lymphovascular or perineural invasion

Satellite lesions

*Breslow thickness and lymphovascular/perineural invasion are most important

44

What is Breslow thickness?

A ruler is used to check how deep the melanoma is.

45

What is the Clark level of a tumour?

Anatomical level that the melanoma has invaded into

46

What are the features of a superficial spreading melanoma?

Prominent epidermal component with buckshot scatter.

Does not have any implication about whether the melanoma is thin or thick.

47

What are the features of a nodular melanoma?

No/minimal intraepidermal component

A cutaneous metastasis needs to be excluded clinically

(Not all melanoma with a nodule is nodular melanoma)

48

Where is lentigo maligna melanoma seen?

Most commonly in sun damaged skin and in elderly patients.

49

What does a lentigo maligna melanoma look like?

Predominantly single cell growth pattern

50

What skin is most commonly affected by acral lentiginous melanomas?

Acral sites (i.e the hands and feet)

May occur under nails

51

What is the most common melanoma affecting dark skinned patients?

Acral lentiginous melanoma

52

Why is regression common in melanomas?

They are among the most antigenic cancers and can trigger a strong immune response which destroys cancerous cells.

53

Why can regression be a bad thing?

Completely regressed melanomas may explain why some patients present with metastatic melanoma but no primary tumour formation.

54

How are melanomas diagnosed?

Atypical pigmented lesions are biopsied with complete excision (if possible) otherwise partial biopsies are taken.

55

What is the problem with partial biopsies of lesions?

Less accurate and carry higher risk of misdiagnosis.

Important cause of litigation.

56

What is done when incomplete biopsy is taken of melanoma?

Size of lesion is included on request form.

Most clinically suspicious area is biopsied.

57

What mutations are common in melanomas?

BRAF, a serine-threonine kinase is mutated in 66% of melanomas.

Most mutations are located in the kinase domain

58

What kind of mutations in BRAF leads to melanoma?

80% are accounted for by a point mutation leading to a substitiution of glutamate for valine at position 600. V600E

59

What pathway does BRAF activate?

MAPK pathway

60

Are BRAF mutations a common cause of naevi?

Yes, they also activate the MAPK pathway but these changes are not significant enough to cause melanomas.

61

What is used now to treat melanomas?

Specific BRAF inhibiting drugs have been developed which are selective for V600E mutations.

62

How successful has BRAF inhibition been for metastatic melanoma?

BRAF inhibiting drugs have increased survival rate in patients with metastatic melanoma. (Treatment effective for approximately a year long)