Histopathological Features of Deep Soft Tissue Epithelioid Angiosarcoma in the Lower Extremity: A Rare Case Report.

BACKGROUND Epithelioid angiosarcoma is an extremely rare malignant disease of the endothelial cells. Most of the previous reports about this disease were regarding clinical features and radiological findings, with limited descriptions of pathological diagnosis. This report aimed to present a reference to increase understanding of the timely diagnosis of epithelioid angiosarcoma. CASE REPORT A 65-year-old male was diagnosed with epithelioid angiosarcoma originating from the deep soft tissue of the lower leg. He had a history of 2 months of rapid swelling and painful in the left lower leg, which occurred after a muscle cramp, and was clinically suspicioius for hematoma. Radiological examination revealed a large heterogeneous soft-tissue mass. Histopathology results showed that the mass was malignant, and the differential diagnosis wasa malignant vascular tumor, melanoma, poorly differentiated carcinoma, clear cell sarcoma, epithelioid sarcoma, and anaplastic large-cell lymphoma. Immunohistochemistry findings confirmed that it was an epithelioid angiosarcoma. CONCLUSIONS This case underscores the difficult of diagnosing epithelioid angiosarcoma. It requires careful pathological investigation and immunophenotype labeling.