70-year-old woman with left atrium mass   

Findings and diagnosis

Microscopic findings

A tumor biopsy showed an avascular core of dense connective tissue surrounded by elastic fibers, smooth muscle cells, and loose connective tissue covered by a single layer of hyperplastic endocardial cells. There are no fine or branching papillae, excluding atrial myxoma. The morphology and immunohistochemical profile are consistent with papillary fibroelastoma.

Differential diagnosis

  • Atrial myxoma
  • Papillary fibroelastoma
  • Cardiac rhabdomyoma
  • Thrombotic endocarditis

Diagnosis: Papillary fibroelastoma