Melanocytic naevi

Question 1

What is it

Answer 1

A melanocytic naevi is a benign skin lesion due to a local proliferation of pigment cells (melanocytes).

Question 2

What are the types

Answer 2

Acquired and congenital

Question 3

What are the types of acquired

Answer 3

Occur in childhood and evolve through a number of steps:

Junctional: flat + pigmented (due to melanocytes at the basal layer of the epidermis)
Compound: raised + pigmented (due to melanocytes at the basal layer of the epidermis + deep in the dermis)
Intradermal: raised + pale (due to melanocytes deep in the dermis)

Question 4

How does congenital navei present

Answer 4

These naevi are present at birth but are very rare.
They are usually quite large and hairy

Question 5

What is a dysplastic naevus

Answer 5

An atypical naevus that may resemble a melanoma, by having ‘ABCDE’ features. They may be part of a syndrome called Familial Atypical Multiple Mole-Melanoma (FAMMM) syndrome, where there are multiple naevi (>50) many of which are atypical and an increased risk of melanoma.

Question 6

What causes blue naevus

Answer 6

A naevus that is blue in colour because the melanocytes are very deep in the skin.

Question 7

What is Beckers naevus

Answer 7

A becker naevus is an irregular, hyperpigmented patch usually affecting the shoulders of males. Darkens and becomes hairy after puberty

Question 8

What is a halo naevus

Answer 8

White halo round the naevus

Question 9

What is a spitz naevus

Answer 9

A red, dome-shaped papule that is commonly found on the face of children.