Intramuscular Cavernous Hemangioma of the Vastus Medialis Muscle in a Young High School Athlete: A Rare Cause of Chronic Anterior Knee Pain.

Intramuscular hemangiomas are rare benign vascular tumors of skeletal muscle that are frequently misdiagnosed due to their deep location and vague presentation. These lesions may present similarly to common orthopedic pathology. We report a 17-year-old male high school athlete with chronic, progressively worsening anteromedial knee pain following prior trauma, associated with progressive swelling. Symptoms persisted despite conservative management, limiting sports participation without impairment in ambulation. The outside radiology report of the patient showed a cystic-appearing lesion in the anteromedial aspect of the knee, initially interpreted as consistent with a ganglion cyst, and less likely a malignancy. Given the chronicity of symptoms and functional limitation, surgical excision was indicated. Surgical pathology report confirmed an intramuscular hemangioma. Postoperatively, the patient experienced improvement in pain with no signs of early recurrence at two-week follow-up. Intramuscular hemangioma should be considered in adolescents with chronic periarticular pain or deep soft-tissue lesions, particularly when symptoms significantly limit activity, chronicity is involved, and imaging suggests an intramuscular vascular process. Surgical excision can be diagnostic and potentially curative when complete resection is achieved, and awareness of this pathology may reduce delays in diagnosis and unnecessary interventions.