Melanocytic Lesions

Question 1

what gene determines the balance of pigment in skin and hair?

Answer 1

melanocortin 1 receptor gene

Question 2

eumelanin hair colour

Answer 2

any colour apart from red

Question 3

phaeomelanin hair colour

Answer 3

red hair

Question 4

role of the MC1R

Answer 4

turns phaeomelanin into eumelanin

Question 5

what does one defective copy of MC1R cause?

Answer 5

freckling

Question 6

what does two defective copies of MC1R cause?

Answer 6

red hair

freckles

Question 7

define freckles (ephilides)

Answer 7

patchy increase in melanin pigmentation (reflects clumpy distribution in melanocytes)

Question 8

what causes more freckles occur

Answer 8

UV exposure

Question 9

does pale skin have fewer melanocytes?

Answer 9

yes

Question 10

what are actinic lentigines

Answer 10

age or liver spot

Question 11

what are actinic lentigines related to?

Answer 11

UV exposure

Question 12

where are actinic lentigines common?

Answer 12

face
forearms
dorsal hands

Question 13

define melanocytic naevi

Answer 13

moles

Question 14

define congenital melanocytic naevi

Answer 14

birthmark

if large there is risk of developing into melanoma

Question 15

describe usual type acquired naevi

Answer 15

melanocyte keratinocyte ratio breaks down

benign lesions

Question 16

stages in naevus development

Answer 16

junctional naevus= cluster at DEJ
compound naevus= dermis (migrate down skin) and moles elevate as they mature
intradermal naevus= entirely dermal

Question 17

appearance of dysplastic naevi

Answer 17

above 6mm in diameter
variegated pigment
border asymmetry
atypical architecture
host reaction involving fibrosis and inflammation

Question 18

two ways a dysplastic naevi can develop

Answer 18

sporadic

familial

Question 19

three examples of rare naevi

Answer 19

halo naevi
blue naevi
spitz naevi

Question 20

describe spitz naevus

Answer 20

under 20 years
large spindle and/or epitheloid cells
pink colouration due to vascularisation
(malignant variant called spitzoid)