Background: Atypical fibroxanthoma (AFX) is a rare cutaneous spindled cell neoplasm. For both diagnostic and therapeutic purposes, it is important to distinguish AFX from other poorly differentiated tumors, including undifferentiated pleomorphic sarcoma (UPS).
Objective: The authors aimed to identify the clinical, histologic, and immunohistochemical expression of LN2, ezrin, and CD10 in AFX and UPS tumors.
Methods and materials: The authors retrospectively examined the charts of patients with AFX and UPS treated with Mohs micrographic surgery (MMS) at 2 academic institutions. Patient demographics, tumor characteristics, and clinical course data were collected. Immunohistochemical stains were performed on primary and recurrent AFX and UPS tumors with monoclonal antibodies against the B-cell marker LN2 (CD74), CD10, and ezrin.
Results: In the series of 169 patients with AFX included in this study, local recurrence was rare at 3%. In contrast, the seven patients with UPS had an aggressive clinical course with 1 local recurrence and 2 distant metastases. Immunohistochemistry staining for ezrin, LN2, and CD10 were similar in AFX and UPS tumors.
Conclusion: AFX can be treated with MMS with rare instances of recurrence. Undifferentiated pleomorphic sarcoma has a more aggressive clinical course with increased risk for recurrence and metastasis. Staining with ezrin, LN2, and CD10 did not differentiate AFX or UPS tumors.