Extensive tumoral melanosis associated with ipilimumab-treated melanoma

Tumoral melanosis describes a pigmented lesion clinically similar to melanoma but on histology reveals dense aggregates of melanin-laden, benign macrophages without malignant cells. In the few reported cases so far, tumoral melanosis has arisen in the skin or lymph node of a patient with a regressed melanoma or an epithelioid tumour. As a marker of regressed primary melanoma, its discovery may prompt investigation and surveillance for undiagnosed local or metastatic disease. Here, we present a unique case of extensive tumoral melanosis arising during ipilimumab treatment of in-transit metastases from a previously excised melanoma.