CYTOLOGIC FEATURES OF SYNOVIAL SARCOMA WITH EMPHASIS ON THE MONOPHASIC FIBROUS VARIANT - A MORPHOLOGIC AND IMMUNOCYTOCHEMICAL ANALYSIS OF BCL-2 PROTEIN EXPRESSION

BACKGROUND. Monophasic fibrous synovial sarcoma (SS) is the most commo n variant of SS but few cytologic studies concerning this entity are a vailable. bcl-2 protein immunoexpression has been described as a chara cteristic marker of SS and is useful for its differentiation from othe r sarcomas. METHODS. Twelve cytologic specimens from 11 patients with histologically proven SS were reexamined. Ten samples were obtained by fine-needle aspiration and in two cases fluid from cystic tumoral are as was obtained at surgery. Nine cases corresponded to monophasic fibr ous tumors and two to biphasic tumors. Immunoexpression of bcl-2 was e valuated in all histologic specimens and in six cytologic samples. bcl -2 protein also was evaluated in 13 soft tissue tumors. RESULTS, All c ytologic specimens had a similar appearance. Most smears were highly c ellular and were comprised of densely packed, tridimensional groups an d numerous isolated, round to oval cells. Remarkable findings included cellular monomorphism and vascular structures within the cell groups. Only one case showed cytologic evidence of epithelial differentiation . Immunoexpression of bcl-2 protein was present in 10 of the 11 histol ogic specimens (90.9%) and in 5 of the 6 cytologic samples (83.3%). A positive result also was observed in malignant fibrous histiocytoma, d ermatofibrosarcoma protuberans, infantile hemangiopericytoma, pleomorp hic liposarcoma, and malignant solitary fibrous tumor. CONCLUSIONS, Al though cytomorphologic features of SS are characteristic enough to per mit its recognition, clinical correlation is necessary for its correct diagnosis. The immunoexpression of bcl-2 protein is not specific of S S and other soft tissue tumors can show a similar positive reaction. ( C) 1998 American Cancer Society.