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imed3004 COPY > Disorders of Pigmentation and Melanocytes > Flashcards

Disorders of Pigmentation and Melanocytes Flashcards

1
Q

What is vitiligo?

A

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

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2
Q

Who most commonly gets vitiligo?

A

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

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3
Q

What is the average age of onset of vitiligo?

A

20 years

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4
Q

What happens in histology of vitiligo?

A

Melanocytes are missing.

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5
Q

What is melasma?

A

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

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6
Q

What causes melasma?

A

Hyperfunctioning melanocytes reacting to sun

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7
Q

What is post inflammatory pigment alteration?

A

Occurs after a variety of inflammatory and traumatic processes.

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8
Q

What does colour of post inflammatory pigment alteration depend on?

A

Colour depends on complex interplay of factors

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9
Q

What does histology show on post inflammatory pigment alteration?

A

Melanophages in superficial dermis

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10
Q

What is ephelis?

A

Freckles

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11
Q

What triggers formation of ephelis/freckles?

A

Wax and wane with sun exposure

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12
Q

What does histology show with ephelis?

A

Normal epidermal architecture with increased keratinocyte pigmentation.

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13
Q

What is lentigo simplex?

A

Small flat darkly pigmented macule

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14
Q

What comes in fewer numbers ephelides or lentigo simplex?

A

Lentigo come in fewer numbers and are more darkly pigmented

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15
Q

What type of proliferation is lentigo simplex?

A

It is a melanocytic proliferation

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16
Q

What other growth is lentigo simplex similar to?

A

Junctional melanocytic naevus

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17
Q

What are the important histological features of lentigo simplex?

A

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

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18
Q

What are the clinical features of benign melanocytic naevus?

A

Small

Well circumscribed

Even colouration

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19
Q

What are the histological features of common benign melanocytic naevus?

A

Symmetrical

Cells predominantly in nests

Round to oval, even nuclei

Maturation as the cells get deeper

Classified as junctional, compound, and intradermal

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20
Q

How are benign melanocytic naevi distinguished from malignant growths?

A

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.

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21
Q

What is a spitz naevus?

A

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

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22
Q

Which demographic commonly gets a spitz naevus?

A

Children and young adults

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23
Q

What is a blue naevus?

A

A dermally based benign lesion that is comprised of dendritic melanocytes

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24
Q

What are the melanomas that look like spitz naevi called?

A

Spitz melanomas

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25
Q

What are congenital naevi?

A

Large, uncommon manifestation of congenital naevi

26
Q

What are the issues associated with congenital naevi?

A

They may present significant cosmetic problems

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

27
Q

What are dysplastic naevi?

A

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

28
Q

Is the risk of dysplastic naevus becoming a melanoma high?

A

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
Q

What do dysplastic naevi look like?

A

Less symmetrical than benign naevi

More single cell growth

Some larger, darker nuclei

Fibrosis in upper dermis

Cytological atypia

30
Q

What is done to dysplastic naevi?

A

Despite low risk of melanoma formation they are excised.

31
Q

What is a melanoma?

A

Malignant tumour derived from melanocytes

32
Q

Does a melanoma show up only in skin?

A

No, it can rarely show up in other organs.

33
Q

How common is melanoma?

A

4th most common cancer in Australia.

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

34
Q

What is the survival rate of melanoma?

A

96% after 5 years if caught early

63% if there is local spread

34% if there is metastatic spread

35
Q

What are the risk factors for melanoma?

A

Strongest:

Family history

Large numbers of benign or atypical naevi

Previous melanoma

Others:

Immunosuppression

Sun sensitivity

Exposure to UV radiation

36
Q

How is melanoma diagnosed?

A

ABCDE

Asymmetrical

Border irregularity

Colour variability

Diameter >6mm

Evolving

37
Q

What are the microscopic features of melanoma?

A

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
Q

What is “buckshot” scatter?

A

Scatter of cells into epidermal ridges

39
Q

What cytological atypia are seen in melanomas?

A

Nuclear enalrgement

Hyperchromasia

Irregularity

Prominent nucleoli

40
Q

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

A

Growth within the epidermis.

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

41
Q

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

A

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

42
Q

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

A

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

This stage implies a capacity for metastatic spread.

43
Q

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

A

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
Q

What is Breslow thickness?

A

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

45
Q

What is the Clark level of a tumour?

A

Anatomical level that the melanoma has invaded into

46
Q

What are the features of a superficial spreading melanoma?

A

Prominent epidermal component with buckshot scatter.

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

47
Q

What are the features of a nodular melanoma?

A

No/minimal intraepidermal component

A cutaneous metastasis needs to be excluded clinically

(Not all melanoma with a nodule is nodular melanoma)

48
Q

Where is lentigo maligna melanoma seen?

A

Most commonly in sun damaged skin and in elderly patients.

49
Q

What does a lentigo maligna melanoma look like?

A

Predominantly single cell growth pattern

50
Q

What skin is most commonly affected by acral lentiginous melanomas?

A

Acral sites (i.e the hands and feet)

May occur under nails

51
Q

What is the most common melanoma affecting dark skinned patients?

A

Acral lentiginous melanoma

52
Q

Why is regression common in melanomas?

A

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

53
Q

Why can regression be a bad thing?

A

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

54
Q

How are melanomas diagnosed?

A

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

55
Q

What is the problem with partial biopsies of lesions?

A

Less accurate and carry higher risk of misdiagnosis.

Important cause of litigation.

56
Q

What is done when incomplete biopsy is taken of melanoma?

A

Size of lesion is included on request form.

Most clinically suspicious area is biopsied.

57
Q

What mutations are common in melanomas?

A

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

Most mutations are located in the kinase domain

58
Q

What kind of mutations in BRAF leads to melanoma?

A

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

59
Q

What pathway does BRAF activate?

A

MAPK pathway

60
Q

Are BRAF mutations a common cause of naevi?

A

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

61
Q

What is used now to treat melanomas?

A

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

62
Q

How successful has BRAF inhibition been for metastatic melanoma?

A

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

imed3004 COPY (50 decks)

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