Unique Dermoscopic and Histopathologic Features of Melanoma Arising in a Patient With BAP1 Tumor Predisposition Syndrome.

Breast cancer gene 1 ()-Associated Protein Tumor Predisposition Syndrome (BAP1-TPDS) is a relatively newly discovered syndrome that may develop a variety of malignancies, including atypical melanoma resembling Spitz nevi. Dermoscopic and molecular findings aid in diagnosing melanoma in BAP1-TPDS, and clinicians should have a high index of suspicion and a low threshold for screening and diagnostic testing for cutaneous malignancies in these patients. We describe an atypical, amelanotic melanoma in a 45-year-old male with a history of BAP1-TPDS and nodular melanoma. The patient presented with a rapidly evolving lesion on the right arm. Given the patient's prior history of melanoma and of heterozygous gene mutation, histopathological and molecular analysis was performed on the lesion, revealing a diffuse loss of expression and multiple chromosomal aberrancies. In these cases, histopathological and molecular analysis remain the keys to diagnosis, but astute dermoscopic evaluation may help clinicians avoid initial diagnostic confusion and delays in treatment. Melanoma should always be considered in patients with BAP1-TPDS, even in the absence of classic gross, dermoscopic, histopathological, and molecular characteristics of typical melanoma.