Diagnosis:

Superficial spreading melanoma.

Comments:

Note the abrupt changes in cell type from area to area. Some melanoma cell groups show a naevoid (monomorphous, small cell) phenotype. It is very obvious here, but to a lesser extent this phenomenon is commonly present in melanoma. Probably it reflects the genetic instability of melanoma, with outgrowth of subclones that differ genotypically, and therefore phenotypically, from each other. Some of this variability is even visible macroscopically (variations in colour, contour, raised or flat aeras, focal regression), forming important clinical clues that the lesion is a melanoma.