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LN2, CD10, and Ezrin Do Not Distinguish Between Atypical Fibroxanthoma and Undifferentiated Pleomorphic Sarcoma or
Allison Hanlon1, Thomas Stasko, Dan Christiansen
1*Division of Dermatology, Department of Medicine, Vanderbilt University, Nashville, Tennessee; †Department of Dermatology, University of Oklahoma, Oklahoma City, Oklahoma; ‡Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut.
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.

