Late Onset Achromatic Melanoma Arising in a Giant Congenital Melanocytic Nevus.

A 61-year-old woman, with a lifelong history of a giant congenital melanocytic nevus in the occipital region with secondary development of giant melanoma is presented. Surgical excision was performed, and the histopathological evaluation confirmed the diagnosis of Giant Malignant Melanoma (GMM) with a maximum tumour thickness of 16 mm. Nowadays, there is tremendous uncertainty regarding how giant congenital melanocytic nevi (GCMN) should be treated. The standard approach to patients with late onset giant congenital melanocytic nevi (GCMN is based on two main considerations: (1) obtain an acceptable cosmetic results with the purpose to decrease the psychosocial inconvenience to each patient, and (2) to attempt to minimise the risk of development of malignant transformation. Unfortunately complete surgical removal of the GCMN is usually difficult and very often impossible without subsequent functional or cosmetic mutilations.