title: Atrial myxoma: a tumour in search of its origins.
abstract: OBJECTIVE
  To determine whether atrial myxomas express antigens suggesting a neural origin.
  
  
  METHODS
  A retrospective analysis based on immunohistochemical examination of myxoma tissue.
  
  
  METHODS
  Atrial myxomas excised by two tertiary referral cardiothoracic surgical units.
  
  
  METHODS
  24 excised atrial myxomas. Three were from known cases of familial myxoma syndrome.
  
  
  METHODS
  Immunohistochemical identifications of three neuroendocrine markers (protein gene product (PGP) 9.5, neurone specific enolase (NSE), synaptophysin) and S100 antigen; CD34 and von Willebrand factor; and chi smooth muscle actin to identify possible Schwann cell differentiation, endothelial cells, and smooth muscle cells respectively.
  
  
  RESULTS
  The myxoma cells were PGP 9.5 positive in 18, S100 positive in 16, and NSE positive in 12. Of the 12 NSE positive myxomas seven were synaptophysin positive. All tumours that were NSE positive were also S100 and PGP 9.5 positive. The tumour surface was partially covered by myxoma cells, partly by endothelial cells.
  
  
  CONCLUSIONS
  The histological appearances of myxomas with stellate cells embedded within a loose connective tissue stroma, abundant basophil cell infiltration, and the presence of pericellular type IV collagen are similar to nerve sheath tumours (neurofibromas) at other sites. A significant proportion of myxomas also express Schwann cell and neuroendocrine differentiation markers. These features cannot prove the origin of myxomas because tumours may develop aberrant phenotype expression but they do accord with the view that myxomas originate from endocardial sensory nerve tissue.
authors.affiliation: Royal Postgraduate Medical School, Hammersmith Hospital, London.
authors.forename: D M
authors.initials: DM
authors.lastname: Krikler
authors.forename: J
authors.initials: J
authors.lastname: Rode
authors.forename: M J
authors.initials: MJ
authors.lastname: Davies
authors.forename: N
authors.initials: N
authors.lastname: Woolf
authors.forename: E
authors.initials: E
authors.lastname: Moss
mesh_terms: D000951:Antigens, Neoplasm / Q000032:analysis*; D006325:Heart Atria; D006338:Heart Neoplasms / Q000276:immunology* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D009232:Myxoma / Q000276:immunology* / Q000473:pathology; D009419:Nerve Tissue Proteins / Q000276:immunology*; D009479:Neuropeptides / Q000276:immunology; D010751:Phosphopyruvate Hydratase / Q000276:immunology; D012189:Retrospective Studies; D009418:S100 Proteins / Q000276:immunology; D016708:Synaptophysin / Q000276:immunology; D043222:Ubiquitin Thiolesterase
chemical_list: D000951:Antigens, Neoplasm; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D009418:S100 Proteins; D016708:Synaptophysin; D043222:Ubiquitin Thiolesterase; D010751:Phosphopyruvate Hydratase