SPINDLE-CELL HEMANGIOENDOTHELIOMA - AN IMMUNOHISTOCHEMICAL AND FLOW CYTOMETRIC STUDY OF 6 CASES

Six cases of spindle cell hemangioendothelioma (SCH) are presented wit h immunohistochemical and flow cytometric analyses, One case was assoc iated with Maffucci's syndrome. All lesions were solitary or multifoca l in the extremities, and prepresentation duration ranged from years t o decades, One case recurred but none had metastases. Histologically, in four of the six cases the main lesions appeared to arise within ves sels, predominantly muscular vessels, All lesions consisted of caverno us hemangioma-like areas and solid cellular areas resembling Kaposi's sarcoma, Cellular atypia was minimal, At the periphery of the lesions, a cluster of large thick or thin walled, and probably malformed, vess els were observed, Immunohistochemically, factor-VIII related antigen, CD34, vimentin, and lectin binding Ulex europaeus agglutinin 1 staine d endothelial cells lining vascular channels, and vacuolated, or epith elioid cells, Spindle cells in the solid areas were negative for these endothelial markers except for vimentin, but showed divergent positiv e immunoreactions of HHF35, alpha-smooth muscle actin, desmin, and col lagen type IV, Five cases were diploid and one was aneuploid, There wa s no significant correlation among DNA ploidy, S-phase fraction, and l ocal recurrence in SCH although the number of cases examined was small , These results suggest SCH may be a benign lesion, probably a reactiv e process, rather than a low-grade angiosarcoma.