[The so-called cardiac myxoma. Histological, electron microscopical, immunofluorescence, and biochemical investigations in 3 cases (author's transl)].

Three cardiac Myxomas were studied by light-, immuno-fluorescence and electron microscopy. Acid mucopolysaccharides of the tumour were isolated chromatographically. The surfaces of the "myxomas" were papillary in two cases and smooth in one. The smooth surfaced tumour recurred six months after primary resection; histological specimens were more cellular than those of the papillary tumors and showed nuclear polymorphism and mitoses. The cells of two papillary tumours were identified as endocardial by electron microscopy, however, the cells of the smooth surfaced tumour were typical myofibroblasts. In both types of "myxomas" the cells were rich on cytoplasmic filament that contained acto-myosin. Biochemical investigation failed to reveal any difference between the acid mucopolysaccharide pattern of the two tumour types; isolated mucopolysaccharides being typical for embryonal mesenchymal tissue. The authors agree with Albertini (1963), that "cardiac myxoma" is a misnomer for two different typical endocardial tumours: a true endothelioma and a "special fibroma" (myofibroma or myofibrosarcoma).