Synovial haemangioma of the knee joint: diagnosis by arthroscopy.

Synovial haemangiomas are a rare cause of recurrent knee effusions. The problem usually presents in childhood, but the diagnosis is often not made for many years. Clinical, laboratory, and radiographic diagnosis is often non-specific, leading to prolonged diagnostic uncertainty. Arteriography, venography, thermography, and computer tomography may be useful once the diagnosis is made. Arthroscopy should be considered early on to make the diagnosis and biopsy the tumor so that further surgery, studies, and treatment can be carried out.