Melanocytic Lesions

Question 1

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

Answer 1

melanocortin 1 receptor gene

Question 2

what does the MC1R gene do?

Answer 2

turns phaeomelanin (red) into eumelanin (other colours)

Question 3

what does defective copies of the MC1R gene cause?

Answer 3

one defective copy causes freckles and two causes freckles and red hair

Question 4

another name for freckles

Answer 4

ephelides

Question 5

define ephelides (freckle)

Answer 5

patchy increase in melanin pigmentation and reflects clumpy distribution of melanocytes

Question 6

when do freckles occur

Answer 6

after sunlight exposure

Question 7

another name for age/liver spots

Answer 7

actinic lentigines

Question 8

cause of actinic lentigines

Answer 8

UV exposure

Question 9

where are actinic lentigines found?

Answer 9

face
forearms
dorsal hands

Question 10

what is a melanocytic naevi?

Answer 10

birthmark

Question 11

describe congenital melanocytic naevi

Answer 11

large lesions that have a risk of developing into melanoma

Question 12

describe usual type acquired naevi

Answer 12

melanocyte, keratinocyte ratio breaks down

elevate as they mature

Question 13

describe dysplastic naevi

Answer 13

generally >6mm, can be sporadic or familial (FH of melanoma increases risk as there is autosomal inheritance)

Question 14

presentation of halo naevi

Answer 14

peripheral halo of depigmentation

Question 15

describe blue naevi

Answer 15

pigment-rich dendritic spindle cells

Question 16

describe spitz naevi

Answer 16

usually under 20
pink colouration due to vasculature
malignant variant called spitzoid