Hemorrhagic epithelioid and spindle cell hemangioma: a newly recognized, unique vascular tumor of bone.

BACKGROUND: Epithelioid vascular tumors of bone are uncommon and include epithelioid hemangioma, epithelioid hemangioendothelioma, and epithelioid angiosarcoma. It is important to distinguish among them because they have significantly different biologic potential and require different forms of therapy. In the current study the authors describe six cases of a distinct benign epithelioid and spindle cell vascular tumor of bone that, because of their unusual morphology, were confused with aggressive vascular neoplasms.
METHODS: Cases were retrieved from the surgical pathology files of the Department of Pathology or from the consultation files of one of the authors. Hematoxylin and eosin stained slides were examined. Immunohistochemistry was performed on two cases and electron microscopy was performed on one case.
RESULTS: The tumors arose in the small bones of the hands and feet and the tibia. Three patients had multifocal bone disease at the time of presentation. Histologically, all lesions were comprised of lobules of spindle cells that grew focally in a fascicular pattern and were associated with abundant hemorrhage. Plump epithelioid cells were intermixed and were present focally in the interlobular areas as well, in which they lined larger, more well developed vascular spaces, often protruding into the vascular lumen in a "tombstone" fashion. Immunohistochemically and ultrastructurally the neoplastic cells had features of endothelium. One case was treated by amputation, one by resection, three by curettage, and one by curettage plus radiation therapy. None of the lesions was locally aggressive nor did any metastasize.
CONCLUSIONS: The authors believe that hemorrhagic epithelioid and spindle cell hemangioma of bone is a histologically benign bone tumor. It should be distinguished from malignant epithelioid vascular tumors of bone, which have metastatic potential and need to be treated more aggressively.