A previously healthy, fair-skinned professional golfer aged 69 years with a history of frequent outdoor sun exposure presented to the surgery clinic with a mass on his left upper back, which he first noted 1 year ago as a small nodule on his back. It grew rapidly throughout the past year, becoming increasingly painful and bleeding easily with light contact.Clinical examination revealed an 8 × 6 × 4-cm multilobulated, purplish lesion that was fungating and friable (Figure 1). He also had a palpable, hard mass in the left axilla. He had no other lesions elsewhere on his body. A punch biopsy of the back mass revealed immunohistochemistry strongly positive for S-100, MART-1, and HMB-45. Computed tomographic and positron emission tomographic scans demonstrated a fludeoxyglucose-avid lesion on the back extending into the subcutaneous fat and fludeoxyglucose-avid uptake in the left axilla. Figure 1. A 8 × 6 × 4-cm multilobulated, purplish lesion on the back that was fungating and friable. WHAT IS YOUR DIAGNOSIS? A. Cavernous lymphangioma B. Nodular basal cell carcinoma C. Squamous cell carcinoma D. Nodular melanoma Clinical Review & Education