Age / Sex : 46 / M

Chief complaint: Right knee pain for five years

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Courtesy: Byeong Seong Kang, Department of Radiology, University of Ulsan College of Medicine, Ulsan University Hospital, Ulsan, Korea

Synovial hemangioma

Discussion

Findings:

1) Plain radiography

-Increased radiopacity of infrapatellar fat

2) MR

-Axial fat-suppressed T2-weighted image: a lobular-shaped mass with heterogeneously hyperintense signal intensity

-Sagittal T1-weighted image: isointense relative to skeletal muscle

-Sagittal, enhanced T1-weighted image: homogeneous intense enhancement

Differential Diagnosis:

Synovial hemangioma

Synovial sarcoma

Discussion:

Synovial hemangioma is a rare benign vascular malformation that usually affects children and young adults and occurs predominantly in the knee. Patients usually present with joint pain, swelling, and spontaneous hemarthrosis. Conventional radiographs of a patient with synovial hemangioma often demonstrate a nonspecific soft-tissue mass. Phleboliths are not uncommon. On T1-weighted MR images, synovial hemangioma appears hypo- or isointense to muscles. Large venous hemangiomas may cause high signal intensity on T1-weighted sequences caused by slow blood flow. On T2- or fat-suppressed T2-weighted MR images, hemangiomas show hyperintense areas. Low-signal intensity linear structures seen throughout the lesion on T2-weighted images are believed to represent fibrous septa or vascular channels. Large lesions may show heterogeneous enhancement after intravenous administration of a gadolinium chelate.

References:

1. Sheldon PJ, Forrester DM, Learch TJ. Imaging of intraarticular masses. Radiographics. 2005;25:105-19.


2. Larbi A, Viala P, Cyteval C, Snene F, Greffier J, Faruch M, et al. Imaging of tumors and tumor-like lesions of the knee. Diagn Interv Imaging. 2016;97:767-77.


3. Sasho T, Nakagawa K, Matsuki K, Hoshi H, Saito M, Ikegawa N, et al. Two cases of synovial hemangioma of the knee joint: Gd-enhanced image features on MRI and arthroscopic excision. Knee. 2011;18:509-11.