title: Cardiac myxoma is rich in factor XIIIa positive dendrophages: immunohistochemical study of four cases.
abstract: Cardiac myxoma is an enigmatic tumour thought to arise from primitive cardiac mesenchymal cells. Factor XIIIa+ dendrophages are tissue histiocytes that are active in tissue repair and thrombosis. To explore whether factor XIIIa+ dendrophages play a role in cardiac myxoma morphogenesis, we stained four cases with an antiserum against coagulation factor XIIIa (FXIIIa). We also used antibodies recognizing CD34, CD31, and S-100 protein. Samples of valvular endocardium from 12 and 16 week fetuses and two adult autopsies were compared with the four myxomas. All cardiac myxomas had rounded and dendritic FXIIIa+ cells admixed with more numerous CD34+ spindle and stellate myxoma cells. The CD34+ cells formed multicellular syncytia and capillary sprouts. Many of these syncytial structures also expressed CD31 and, to a lesser extent, S-100 protein, strongly in two cases and more focally in two. Fetal subendocardium was composed of CD34+ stellate fibroblast-like cells invested with scattered FXIIIa+ histiocytes; no S-100+ cells were detected. Our findings confirm that cardiac myxomas are composed of CD34+ primitive subendocardial cells. These cells show a capacity for CD31+ endothelial differentiation. In cardiac myxoma, the CD34+ myxoma cells are accompanied by numerous FXIIIa+ dendrophages, the presence of which suggests abnormal organizing thrombus-like differentiation in cardiac myxoma morphogenesis.
authors.affiliation: Department of Pathology, University Hospital, Health Sciences Centre, SUNY at Stony Brook, USA.
authors.forename: L
authors.initials: L
authors.lastname: Berrutti
authors.forename: J S
authors.initials: JS
authors.lastname: Silverman
mesh_terms: D018952:Antigens, CD34 / Q000032:analysis; D001344:Autopsy; D004699:Endocardium / Q000737:chemistry / Q000196:embryology; D006338:Heart Neoplasms / Q000201:enzymology* / Q000473:pathology; D006644:Histiocytes / Q000201:enzymology* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D009232:Myxoma / Q000201:enzymology* / Q000473:pathology; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis; D009418:S100 Proteins / Q000032:analysis; D017154:Stromal Cells / Q000473:pathology; D011503:Transglutaminases / Q000276:immunology*
chemical_list: D018952:Antigens, CD34; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D009418:S100 Proteins; D011503:Transglutaminases