Tumoral melanosis associated with combined BRAF/MEK inhibition (dabrafenib/trametinib) in metastatic melanoma

Abstract

Tumoral melanosis describes a pigmented lesion clinically suspicious for melanoma but characterized histopathologically by aggregates of melanin-laden macrophages without malignant cells.1, 2 Limited cases of tumoral melanosis exist in the literature; often it is identified on the skin as a macule or papule or may present in the lymph nodes of a patient with a history of melanoma or a longstanding atypical lesion, and further investigation can yield undiagnosed local or metastatic disease.2, 3 Recently, there are examples of tumoral melanosis arising during treatment for melanoma, mostly with anti-PD-1 or anti-CTLA-4 therapy.1, 2 Garrido et al4 reported on a patient who developed plaques near in-transit metastases after starting dabrafenib-trametinib, with biopsy showing granulomatous inflammation admixed with melanophages. They are the first, to our knowledge, to describe tumoral melanosis with this treatment.4 The following is a unique case of nodular tumoral melanosis identified in a patient on dabrafenib-trametinib for metastatic melanoma.