Synovial Hemangioma

Synovial hemangiomas (intrasynovial hemangiomas) are rare masses that arise within the subsynovial connective tissue. They can be localized or diffuse and are most commonly seen in the knee. Less common sites include elbow, ankle, wrist, temporomandibular joint, and tendon sheaths.

Patients are usually children and adolescents who present with pain, limited range of motion, or a mass that shrinks when the affected limb is elevated. Adjacent cutaneous or soft tissue hemangiomas are occasionally seen.

Synovial hemangiomas can intermittently bleed, causing a hemosiderotic synovitis with pain and joint swelling. The bleeding is rarely as severe as that seen with the bleeding diatheses (e.g., hemophilia) and early osteoarthritis is usually not seen.

Radiographic findings can mimic a soft tissue mass or a joint effusion. When seen, phleboliths and bone erosions can suggest the diagnosis. Angiography can reveal contrast pooling in dilated vascular spaces with early venous drainage. CT may reveal a lobulated mass with heterogeneous attenuation and areas of fat. MRI reveals an intra-articular or juxta-articular mass with intermediate signal intensity on Tl-weighted images and high signal intensity on T2-weighted images. Hypointense channels or septa can be seen on T2-weighted images. And fluid-fluid levels can occasionally be seen.

References

• Cotten A, Flipo RM, Herbaux B, Gougeon F, Lecomte-Houcke M, Chastanet P. Synovial haemangioma of the knee: a frequently misdiagnosed lesion. Skeletal Radiol. 1995 May;24(4):257-61.
• Greenspan A, Azouz EM, Matthews J 2nd, Décarie JC. Synovial hemangioma: imaging features in eight histologically proven cases, review of the literature, and differential diagnosis. Skeletal Radiol. 1995 Nov;24(8):583-90.
• Nielsen GP, Rosenberg AE, O'Connell JX, Kattapuram SV, Schiller AL. Tumors and diseases of the joint. Semin Diagn Pathol. 2011 Feb;28(1):37-52.