Atrial myxoma is the most common primary tumour of the heart. It is benign.

Features:

• Hypocellular myxoid polypoid mass with cells that are:
  • Perivascular arrangement,
  • Finely vacuolated eosinophilic cytoplasms,
  • Polygonal/elongated cell shape,
  • Mononuclear or multinucleated.
• May contain macrophages, other inflammatory cells.

• 
  High mag.
• 
  Intermed. mag.
• 
  Low mag.
• 
  High mag. with endothelium.
• 
  Low mag. with interface to muscular wall.