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

Area of Science:

• Orthopedic Surgery
• Pathology
• Radiology

Background:

• Pigmented villonodular synovitis (PVNS) is a rare condition that typically affects joints.
• PVNS in the lumbar spine is exceptionally rare, with no prior reports in a pars defect associated with lumbar spondylolysis.

Observation:

• A 14-year-old female presented with chronic low back pain.
• Imaging revealed spondylolysis at L5 with a tumorous mass in the left L5 pars defect.
• MRI demonstrated characteristic findings of PVNS with gadolinium enhancement.

Findings:

• Pathological diagnosis confirmed PVNS after a computed tomography-guided needle biopsy.
• Surgical resection was performed with gross removal of the tumor.
• Postoperative imaging confirmed no residual lesion, and the patient's clinical course was uneventful.

Implications:

• This case represents the first documented instance of PVNS occurring within a pars defect in lumbar spondylolysis.
• Highlights the importance of considering rare diagnoses in spinal pathology.
• Contributes to the limited literature on spinal PVNS, particularly in pediatric and adolescent populations.