Tenosynovial Giant Cell Tumor, Diffuse Type/Pigmented Villonodular Synovitis in a Pars Defect A Case Report

Study Design. Case report. Objective. To describe a rare case of tenosynovial giant cell tumor, diffuse type/pigmented villonodular synovitis (PVNS) in a pars defect in a patient with lumbar spondylolysis. Summary of Background Date. PVNS rarely occurred in lumbar spine, and no studies in the English literature have reported PVNS in a pars defect in lumbar spondylolysis. Methods. The patient was a 14-year-old female presented with a 5-month history of low back pain. Plain radiography showed spondylolysis at L5 and computed tomography revealed a 1 x 2-cm slightly eroding tumorous mass at the left L5 pars. On magnetic resonance imaging, the mass showed intermediate intensity and gadolinium enhancement on T1-weighted images (WI) and high intensity on T2-WI and T2 STAR-WI. After undergoing computed tomography-guided needle biopsy, a pathological diagnosis of PVNS was made and total gross resection was performed. Results. The gross appearance and the postoperative pathological diagnosis were consistent with PVNS. The postoperative clinical course was uneventful and postoperative computed tomography and magnetic resonance imaging revealed no residual lesion. Conclusion. This is the first report of PVNS occurring in spondylolysis.