Synovial hemangioma of the hip joint in a pediatric patient.

Hemangiomas of the articular synovium are rare and commonly associated with recurrent joint swelling and painful limitation of motion. The knee joint is the most commonly involved site, with most patients diagnosed in the second to third decade of life. Although over 200 cases have been reported in the English-language medical literature, only three have originated within the hip joint, all of which were in adult patients reported in the surgical literature. We describe a histologically proven synovial hemangioma of the hip joint in a pediatric patient that invaded the femur, acetabulum, and adjacent soft tissues, with a detailed discussion of the differential diagnosis based on the radiographic and magnetic resonance imaging (MRI) findings.