Cardiac myxoma. A retrospective immunohistochemical study.

Seven cardiac myxomas were studied by immunoperoxidase and immunofluorescence in formalin fixed and paraffin embedded tissues. Specific antisera to factor VIII related antigens, vimentin, myosin of smooth muscle, actin, desmin, alpha-1-antitrypsin, muramidase, fibrin and prekeratin antigens were used. All myxoma cells reacted positively with antibodies to vimentin and showed no staining reaction with antibodies to alpha-1-antitrypsin, muramidase, myosin, or prekeratin. Factor VIII related antigen was found only in endothelial cells and not in myxoma cells proper. Fibrin was found in patchy areas within the stroma. Antisera to actin and desmin failed to react with formalin fixed tissue. Our results suggest that the main cellular component of cardiac myxoma is a primitive mesenchymal cell without immunohistochemical evidence of more specific differentiation.