Sections revealed a dense, fibrous cyst wall with focal hyalinization and a synovial lining that varies from hyperplastic to denuded. The lumen contains proteinaceous fluid and fibrin, while the underlying stroma shows mild chronic inflammation and scattered hemosiderin-laden macrophages. No cellular atypia is present.
Rt. knee popliteal fossa cyst? Backer's cyst.
Soft tissue fragment measured 3.5x2.8x2 cm, showing cyst measuring 2.5x2.5 cm.
Rt. knee cyst, excision: