Intraarticular hemangioma of the knee.

Intraarticular hemangioma is a rare cause of knee pain and effusion. The presentation of unexplained recurrent hemearthrosis associated with no or minimal trauma, skin manifestations of hemangioma, and radiographic and magnetic resonance imaging study results should alert the clinician of this unusual entity. Successful arthroscopic ablation is reported with the use of the holmium:yttrium-aluminum-garnet (YAG) laser.