Aggressive clinical course of epithelioid angiosarcoma in the femur: a case report

Abstract

Background: Epithelioid angiosarcoma is a rare variant of angiosarcoma, and is characterized by an epithelioid morphologic appearance that mimics carcinoma. These tumors usually arise in extraskeletal sites; origination in bone is rare.

Case presentation: A 69-year-old woman presented with right knee pain. Plain radiographs and magnetic resonance imaging showed an osteolytic lesion with a large soft-tissue extension into the distal femur. Under a diagnosis of metastatic carcinoma of unknown origin based on the biopsy specimen, resection and replacement with an artificial joint were performed. Histologic analysis of the resected material confirmed epithelioid angiosarcoma, supported by immunoexpression of cytokeratins and vascular markers. Three months after surgery, metastasis to the bone and lymph nodes was observed, and the patient died of the disease shortly thereafter.

Discussion: Epithelioid angiosarcoma of bone is characterized by an aggressive clinical course. A possibility of epithelioid angiosarcoma of bone should be considered in cases with such epithelial features, particularly if only small specimens are available.

Figure 1

Epithelioid angiosarcoma images. (A) Plain X-radiographs show an osteolytic lesion in the distal femur. (B) This lesion has apparently widened after 1 month. (C) Magnetic resonance imaging shows a lobulated lesion with a low signal on T1-weighted imaging (top) and a heterogeneous signal on T2-weighted imaging (middle), and heterogeneous gadolinium enhancement is observed on T1-weighted imaging (bottom). (D) [¹⁸F]-2-fluoro-2-deoxy-D-glucose positron emission tomography reveals a solitary lesion in the distal femur.

Figure 2

Epithelioid angiosarcoma histology. The tumor is composed of large, epithelioid cells with vesicular nuclei and prominent nucleoli (A), with fibrous stroma (B). (C) Vascular formation and malignant endothelial cells containing erythrocytes are observed. (D) Increased mitotic activity is observed. Immunohistochemically, tumor cells express cytokeratins AE1/AE3 (E) and the vascular marker CD31 (F).

Figure 3

Postoperative epithelioid angiosarcoma images. (A) Three months after tumor resection and artificial joint replacement, plain radiographs show multiple osteolytic lesions at the femur and the tibia (arrows). (B) [¹⁸F]-2-fluoro-2-deoxy-D-glucose positron emission tomography shows multiple lesions extending from the pelvic cavity to the lower extremity.