Magnetic resonance imaging comparison of intra-articular cavernous synovial hemangioma and cystic synovial hyperplasia of the knee

Purpose: To identify and compare magnetic resonance imaging (MRI) characteristics, with and without intravenous contrast medium, of cavernous synovial hemangiomas and cystic synovial hyperplasia. Material and Methods: Four cases of cavernous synovial hemangioma and five of cystic synovial hyperplasia of the knee were studied retrospectively. The patients ( 5 F and 4 M; 15 - 25 years of age) all had long-standing knee pain. At clinical examination we observed elastic swelling and pain without significant joint effusion. The patients underwent conventional radiography and MRI without and following intravenous contrast medium before arthroscopic biopsy. Results: The radiographs were interpreted as negative in all patients. MRI examination without contrast medium revealed a similar multicystic appearance for both lesions. Following intravenous contrast agent administration, cavernous synovial hemangiomas demonstrated avid, rather homogenous enhancement, whereas cystic synovial hyperplasia demonstrated less intense, peripheral enhancement only. Arthroscopy with histological examination of the lesions confirmed the MRI diagnosis in every case. Conclusion: In our experience, cavernous synovial hemangioma and cystic synovial hyperplasia have a similar appearance on unenhanced MRI, but can be reliably differentiated on the basis of enhancement characteristics following intravenous contrast administration.