title: Cystic tumour of the atrioventricular node: a case report and review of the literature.
abstract: Cystic tumour of the atrioventricular node is a rare primary cardiac tumour that can cause complete heart block and sudden death. Here, we describe a male case aged 42 years who suddenly died without a medical and family history of cardiac illnesses. After detailed macroscopic and microscopic examinations, a cystic mass was found in the atrioventricular nodal region. The small lesion was less than 1 cm in diameter, and consisted of small and large cystic spaces and tubular structures lined by flat, cuboidal or squamous epithelium. Immunohistochemical staining revealed the tumour epithelium positive for epithelial membrane antigen, carcinoembryonic antigen, antigen epitopes AE1/AE3, cytokeratins CK5/6 and CK7, but negative for calretinin, HBME-1, Wilms' tumor 1, factor VIII, chromogranin, synaptophysin or smooth muscle actin, suggesting an endodermal rather than mesothelial origin.
authors.affiliation: Department of Pathology, Affiliated Hospital of Dali University, Dali, Yunnan, China. panyun09@163.com
authors.forename: Yun
authors.initials: Y
authors.lastname: Pan
authors.forename: Ji-liang
authors.initials: JL
authors.lastname: Chen
authors.forename: Zheng-jin
authors.initials: ZJ
authors.lastname: Li
authors.forename: Li-xian
authors.initials: LX
authors.lastname: Zhao
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.forename: Yao-kang
authors.initials: YK
authors.lastname: Li
authors.forename: Lin-bo
authors.initials: LB
authors.lastname: Tian
authors.forename: Hua
authors.initials: H
authors.lastname: Guo
mesh_terms: D000328:Adult; D001283:Atrioventricular Node / Q000378:metabolism / Q000473:pathology*; D006338:Heart Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008297:Male