Pigmented villonodular synovitis of lumbar facet joint: a rare cause of nerve root entrapment.

Abstract

A case report of nerve root entrapment due to pigmented villonodular synovitis of lumbar facet joint is reported for which excision was performed. To report a rare cause for nerve root claudication. Pigmented villonodular synovitis is an uncommon synovial abnormality with an estimated incidence of 1.8 cases per million. Large joints, such as knee and hip, are commonly affected. Involvement of the facet joint is very rare. In our case a high index of suspicion from CT and MRI helped us in the appropriate management. A 71-year-old man presented with severe back pain and right-sided L5 sciatica. CT and MRI scans showed a cystic lesion arising from the L5-S1 facet joint. Excision and adequate decompression in the form of undercutting facetectomy were done. The patient had symptomatic improvement with surgery, and at the 3-year follow-up he showed no signs of recurrence. Unless pigmented villonodular synovitis is considered in the differential diagnosis of tumors of the vertebral column causing nerve root claudication, it may be overlooked.