Papulonodular pigmented lesions in a patient with Stage IV malignant melanoma

Abstract

A 78-year-old man received immunotherapy for in-transit metastatic melanoma papulonodules on his left lower abdomen in the form of intralesional injections of talimogene laherparepvec (T-VEC), an oncolytic genetically modified herpes virus. Despite therapy, the colour and size of the lesions remained clinically unchanged; however, histopathological examination revealed only melanophages in the absence of melanoma cells. The diagnosis of tumoral melanosis secondary to immunotherapy with T-VEC was made. This case emphasizes the importance of histopathological evaluation in assessing response to immunotherapy of in-transit metastatic melanoma lesions.