Persistent popliteal pain derived from cavernous hemangioma involving gracilis tendon and tendon sheath.

Hemangiomas arising from tendon and tendon sheath are rarely reported, and may be confused with other lesions of tendons. In this case report, a 19-year-old woman was diagnosed with a cavernous hemangioma originating in the left gracilis tendon and tendon sheath. When her symptoms initially developed, MRI did not delineate the lesion due to the relatively small size of the tumor. Nine years after the onset of the patient's complaints of knee pain and swelling, the tumor was adequately diagnosed on physical examination and MRI, and was resected with complete relief of symptoms.