Melanocytic Naevi

Question 1

What is a melanocytic naevus?

Answer 1

Mole
Localised benign proliferations of melanocytes
Either congenital or acquired

Question 2

Congenital naevi

Answer 2

Present at birth or appear shortly after

Question 3

Acquired naevi

Answer 3

Classified according to microscopic location of the clumps of melanocytes in the skin

Question 4

Acquired naevi - junctional

Answer 4

Occur in childhood
Melanocytes form clusters at the DE junction
Morphology: Circular and macular, brown

Question 5

Acquired naevi - compound

Answer 5

Occur in adolescence
Junctional clusters and groups of melanocytes in dermis
Morphology: nodules of up to 1cm diameter

Question 6

Acquired naevi - intradermal

Answer 6

Occur in adults
Groups of melanocytes in the dermis
Morphology: nodules of up to 1cm diameter

Question 7

Dysplastic naevi

Answer 7

Asymmetrical border
Diameter usually >6mm
Sporadic appearance ; Patient at slightly higher risk of malignant melanoma
Familial ; patient at much higher risk of developing malignant melanoma

Question 8

Blue naevi

Answer 8

Entirely dermal
Common in wrists and scalp
Due to failure of complete migration of melanocytes

Question 9

Halo naevi

Answer 9

Peripheral halo od de-pigmentation