Atypical Fibroxanthoma on the Scalp of a 74-Year-Old Male with an Incidental Finding of an Amelanotic Melanoma on the Back.

Atypical fibroxanthoma (AFX) is a rare spindle-cell tumor of the skin, typically occurring in sun-exposed areas of elderly patients. We report an unusual case of synchronous AFX and amelanotic melanoma in a 74-year-old man. The patient presented with a 7-month history of a bleeding nodule on the scalp. Clinical examination revealed an 18 mm red nodule in diameter with hemorrhagic crust. An additional 23 mm pink-red bleeding nodule in diameter on the back, previously unnoticed by the patient, was also identified. Both lesions were excised with 3-5 mm margins. Histopathological and immunohistochemical analysis of the scalp tumor showed a dermal proliferation of atypical spindle cells with high mitotic activity, Ki-67 expression of approximately 35%, SMA positivity, and negativity for melanocytic and epithelial markers, supporting the diagnosis of AFX. In contrast, the second lesion demonstrated melanocytic markers (Melan A, HMB-45, S-100 positivity), with Breslow thickness of 1 mm and Clark level III, consistent with amelanotic melanoma. The patient was referred for further surgical oncological management. At the last available follow-up, 6 months after excision, the patient showed no clinical evidence of local recurrence, nodal involvement, or distant metastasis. This case highlights the importance of thorough skin examination in patients with cutaneous tumors, as multiple distinct malignancies may coexist.