title: So-called mesothelioma of the atrioventricular node.
abstract: A so-called mesothelioma of the atrioventricular node causing sudden, unexpected death is reported. The tumor is composed of tubular-glandular spaces and surrounded by connective tissue containing reticulin and elastic fibres. The tubular-glandular spaces are lined by a single, cuboidal or multilayered squamoid epithelium. The tumor epithelium contained epithelial mucin and carcinoembryonic antigen (CEA). At the ultrastructural level the epithelium showed tight junctions, desmosomes and a few epithelial cells had preserved blunt microvilli at the luminal cell surface. Many tumor cells contained a large number of cytoplasmic tonofilaments. Our results support the opinion, that the conducting tissue tumor is a lesion arisen from sequestered endodermal elements from the primitive forgut during cardiac organogenesis.
mesh_terms: D000328:Adult; D001283:Atrioventricular Node; D002462:Cell Membrane / Q000648:ultrastructure; D003238:Connective Tissue / Q000648:ultrastructure; D003599:Cytoskeleton / Q000648:ultrastructure; D004547:Elastic Tissue / Q000648:ultrastructure; D004848:Epithelium / Q000648:ultrastructure; D006338:Heart Neoplasms / Q000648:ultrastructure*; D006801:Humans; D007365:Intercellular Junctions / Q000648:ultrastructure; D008297:Male; D008654:Mesothelioma / Q000648:ultrastructure*; D008854:Microscopy, Electron; D009940:Organoids / Q000648:ultrastructure