Atypical fibroxanthoma-like amelanotic malignant melanoma: A case report and literature review

• Main Authors: Chao-Kai Hsu (Author), Sheau-Chiou Chao (Author), Shyh-Jou Shieh (Author), Julia Yu-Yun Lee (Author)
• Format: Book
• Published: Wolters Kluwer Medknow Publications, 2013-09-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 1027-8117; 10.1016/j.dsi.2012.09.007
• Keywords: atypical fibroxanthoma; CD68; melanoma; Dermatology; RL1-803
• Source: Dermatologica Sinica, Vol 31, Iss 3, Pp 140-144 (2013)

Atypical fibroxanthoma (AFX)-like malignant melanoma is very rare. Here, we report a case of amelanotic AFX-like melanoma in a 72-year-old Taiwanese woman presenting with two separate, asymptomatic, enlarging erythematous nodules within a large hypopigmented patch on her left cheek. Histologically, both lesions showed cellular nodules in the reticular dermis separated from the overlying flattened epidermis by a zone of solar elastosis or fibrosis. The tumor consisted of sheets of atypical epithelioid cells arranged in a vague nesting pattern, as well as many atypical large or gigantic cells with one or more, large hyperchromatic, vesicular, or pleomorphic nuclei with prominent nucleoli, and moderate-to-abundant eosinophilic or foamy cytoplasm. Focal intraepidermal proliferation of atypical melanocytes with a pagetoid pattern was found only in the periphery of the main tumor. The tumor cells were moderately to strongly positive for S-100, Melan-A, and HMB-45. The pleomorphic giant cells were focally CD68-positive but CD163-negative. The patient underwent tumor excision followed by radiotherapy due to the narrow surgical margins. A sentinel lymph node biopsy revealed no metastasis of the melanoma. This case illustrates the importance of scrutinizing any subtle proliferation of atypical melanocytes in the epidermis in an AFX-like tumor in order to avoid misdiagnosis.