Primary Mucosal Melanoma of the Penile Urethra: A Case Report of an Extremely Rare Disease with a Unique Molecular Profile

Primary melanomas of the penis are extremely rare, accounting for 0.18% all and less than 2% primary penile malignancies. We present a case mucosal melanoma urethra in an 82-year-old man. His partial penectomy revealed sheets spindling epithelioid tumor cells with pale eosinophilic granular cytoplasm indistinct cell borders, which invaded into corpus spongiosum. Multi-foci situ were identified at surface meatus. Both positron emission tomography (PET) magnetic resonance imaging (MRI) scan one month after showed no evidence metastatic disease. Five months later, F18-fluorodeoxyglucose-PET/computed demonstrated mildly increased F18-fluorodeoxyglucose avidity along ventral marked right inguinal lymph node. Subsequent excision confirmed ulcerated node, respectively. Molecular analysis unique BRAF c.1780G>A mutation, resulting D594N alteration, is first report urethral melanoma. The patient was miserable from infusion immunotherapy (Keytruda), PET that continued to grow, extensive pulmonary disease leading massive pleural effusion. Unfortunately, died 18 his presentation.