Male, 49 years. Pigmented papule, shoulder regionShow diagnosis & comments
Some melanomas show an infiltrative, noncohesive pattern of growth (desmoplastic melanoma is the prima example), others shom a compact, 'pushing' growth pattern, the melanoma cells accumulating so that a papule or nodule results, often with subsequent ulceration: this is an example of such a pattern of growth.
Note the abrupt changes in cell type from area to area. 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.