Primary sclerosing epithelioid fibrosarcoma of chest wall in a patient with breast cancer: a case report

Sclerosing epithelioid fibrosarcoma (SEF) is a rare neoplasm mostly arising in limbs and limb girdles, with a high rate of recurrence. Herein, we describe a rare case of primary SEF in the chest wall with concurrent breast cancer. A 41-year-old female was found to have an asymptomatic mass in the upper chest wall on magnetic resonance imaging that was performed for breast cancer. Histology of the resected tumor showed features of SEF, with epithelioid cells arranged in nests or a retiform pattern within a sclerosing stroma. By immunohistochemistry, the tumor cells showed staining for vimentin and epithelial membrane antigen, and were negative for cytokeratin. EWSR1 rearrangement was found by fluorescence in situ hybridization. She is currently disease free at 29-month follow-up. We herein report a rare case of SEF with concurrent breast cancer. The top differential diagnosis was between SEF and metastatic breast cancer. The distinction is important for implications in tumor staging and clinical management.