Multicentric epithelioid angiosarcoma of the spine: a case report of a rare bone tumor

Epithelioid angiosarcoma (EA) is a high-grade sarcoma of vascular origin. EA is a rare variant of angiosarcoma. It is characterized by large cells with an epethelioid morphology. EA has been reported in sites like skin thyroid, adrenal gland, soft tissue, and rarely in bone.

The current article describes a case of multicentric EA of the spine that presented simultaneously at T4 spine and the posterior one third of the left fourth rib. STUDY DESIGN/SETTINGS: This study included a patient with a rare spinal tumor, which presented insidiously. Radiologically, the lesions were osteolytic with erosion of cortices. The tumor was composed of nests and cords of malignant cells with epithelioid morphology with areas of vascular differentiation, necrosis, and hemorrhage. Anastomosing vascular spaces lined by epithelioid endothelial cells suggested focal endotheliod differentiation.

Histopathological evaluation of the tumor obtained from en bloc resection of the fourth rib and specimen from decompression of the fourth thoracic vertebra was done. Immunohistochemistry showed positivity for endothelioid cell markers like CD31 and factor VIII related antigen. The authors point out the need for immunohistochemical evaluation after careful histological analysis for vascular differentiation for an accurate diagnosis of vascular bone tumors with epithelioid features so that an erroneous diagnosis of metastatic carcinoma can be avoided. EA occurs rarely in bone. EA is marked by the presence of large polygonal epithelioid malignant cells with marked cellular atypia and pleomorphism. The arrangement of the cells may mimic epithelial neoplasm. These types of lesions are a definite diagnostic challenge in bone biopsy. The tumor was treated with en bloc resection of the rib and decompression of the body of T4 spine, followed by megavoltage radiotherapy. Follow-up X-rays showed regression of the tumor at 2 years. CD31 is the most sensitive marker for EA. Even in the absence of obvious vascular differentiation, abundant intratumoral hemorrhage and intratumoral neutrophils are definite morphologic changes that should suggest a vascular origin.

The patient was followed up for 2 years. A conservative surgical approach with a radical course of megavoltage radiotherapy could yield a good result in EA of bone. At the time of writing this report, there is no evidence of tumor recurrence.

It is important to differentiate EA from other tumors because the clinical course and treatment are specific for these conditions. Careful histologic and immunohistochemical analysis will clinch the diagnosis. Even though rare, we stress the importance to be aware of the existence of this tumor, which is essential for correct diagnosis.