Masson's Hemangioma of Knee: A Rare Case Report

Intrasynovial hemangioma, a rare benign vascular lesion of joint cavities, is also called intrasynovial papillary endothelial hyperplasia or Masson's hemangioma (MH). These lesions are characterized by abnormal proliferation of endothelial cells with mild atypia with an organized thrombus. MH follows an individualized protocol for its management. A 22-year-old male gave a 10-year history of the diagnosed and operated (arthroscopically) case of synovial hemangioma of the left knee and presented with similar complaints. There was no history of trauma or infection over the left knee. The movements of the left knee were normal except with terminal restriction of movements. MRI of the left knee suggested intrasynovial low flow vascular malformation within the substance of the synovium. The patient underwent synovectomy of the hemangiomatous lesion in toto without any recurrence in the follow-up period for 8 months. Histopathology confirmed the diagnosis of intravascular papillary endothelial hyperplasia/MH. Although intrasynovial hemangioma is a very rare clinical entity, Orthopedic surgeons should have a high index of suspicion for MH, when a long-standing pain and hemarthrosis of the knee joint is being encountered in the clinical practice.