Pathology of Pigmented Lesions

Question 1

where are melanocytes derived from?

Answer 1

neural crest

Question 2

where do melanoblast migrate in embryogenesis?

Answer 2

skin
uveal tract
leptomeninges

Question 3

what determines balance of pigment in skin and hair?

Answer 3

MC1R (melanocortin 1 receptor) gene

Question 4

what hair colour would you have if you had phaeomelanin?

Answer 4

red

Question 5

what hair colour would you have if you had eumelanin?

Answer 5

anything other than red

Question 6

what does 1 defective copy of MC1R cause?

Answer 6

freckling

Question 7

what does 2 defective copies cause?

Answer 7

freckling and red hair

Question 8

what are lentigines?

Answer 8

age spots related to UV exposure

Question 9

can melanocytic naevi be congenital

Answer 9

yes

Question 10

how are naevi formed?

Answer 10

in infancy the melanocytes:keratinocytes ratio breaks down at various sites

Question 11

what is a junctional naevus?

Answer 11

melanocytes proliferating at the DEJ causing naevus in childhood

Question 12

what is a compound naevus

Answer 12

clusters from junctional naevus joining groups of cells in the dermis forming a new naevus; usually in adolescence

Question 13

what is an intradermal naevus

Answer 13

only melanocytic activity is dermal causing a naevus

Question 14

typical size of a dysplastic naevus?

Answer 14

> 5mm

Question 15

where do blue naevi exist?

Answer 15

dermis

Question 16

what do blue naevi contain?

Answer 16

dendritic spindle cells

Question 17

who tends to get spitz naevi?

Answer 17

people under 20

Question 18

what do spitz naevi look like?

Answer 18

well vascularised melanoma-like naevus

Question 19

what does a spitz naevus look like on the microscope

Answer 19

epidermal hyperplasia

Question 20

which gender gets malignant melanomas more commonly?

Answer 20

females

Question 21

name 4 main types of melanoma`

Answer 21

superficial spreading
acral/mucosal lentiginous
lentigo maligna
nodular

Question 22

which type of melanoma can metastasise?

Answer 22

VGP (vertical growth phase) melanomas i.e nodular

Question 23

what happens in resting growth phase?

Answer 23

melanoma grows as macules

Question 24

what happens in vertical growth phase?

Answer 24

melanoma cells invade the dermis forming an expansile mass with mitoses

Question 25

what types of melanoma have to have RGP before they start VGP?

Answer 25

superficial spreading (SS)
acral/mucosal lentiginous (A/MLM)
lentigo maligna

Question 26

what type of melanoma only grows by VGP?

Answer 26

nodular melanoma

Question 27

What is Breslow depth?

Answer 27

The deepest (in mm) a melanoma tumour invades from the granular layer

Question 28

when would melanoma survival half according to breslow’s depth?

Answer 28

2-4mm

Question 29

what characteristics of a melanoma would affect overall prognosis?

Answer 29

ulceration
metastasis
fast mitotic rate
LN invasion
satellite lesions

Question 30

melanoma treatment?

Answer 30

excision

lymphadenectomy if needed

Question 31

why do blue naevi arise?

Answer 31

failure of complete migration of melanocytes