(P 38) LOCAL RECURRENCE OF DIFFUSE PIGMENTED VILLONODULAR SYNOVITIS IN MAJOR JOINTS: A 15 YEAR-LONG CASE SERIES AT A SINGLE INSTITUTION

Objective: This study aims to evaluate the local recurrence rate of diffuse tenosynovial giant cell tumor or pigmented villonodular synovitis (PVNS) in major joints, namely the knee, hip, ankle, and elbow, over the past decade at a single musculoskeletal oncology specialized institution. Additionally, it seeks to identify potential factors associated with recurrence, such as demographic variables, surgical techniques, and adjuvant therapies.

Methods: A retrospective case series analysis of patients diagnosed with diffuse PVNS who underwent surgical treatment was conducted between 2006 and 2021. Patient records were reviewed to collect data on demographics, joint involvement, history of prior diagnosis and/or procedures, type of surgical intervention (single stage versus 2-stage procedures), use of adjuvant radiotherapy, and recurrence rates. The diagnosis of diffuse PVNS was defined by preoperative MRI or operative report indicating diffuse disease requiring radical synovectomy. Patients with localized or nodular PVNS and those who underwent monoclonal adjuvant treatment were excluded. Skeletally immature patients were excluded from the adjuvant radiation treatment protocol in our series. Recurrence was defined as clinical and/or radiological evidence of PVNS requiring additional intervention. Patients were followed up longitudinally to evaluate the long-term risks of recurrence. Descriptive statistics were performed, and the Kaplan-Meier method was used to calculate the survival function for local recurrence.

Results: A total of 67 patients were diagnosed with PVNS, and of those, 32 were diffuse PVNS cases. Among these cases, 17 (53%) were primary, 7 (22%) had a history of one relapse, and 8 (25%) had a history of multiple prior relapses. The average age was 38 years (+/-16). Seventeen (53%) of the patients were females, while fifteen (47%) were males. The mean follow-up time was 38 months (minimum: 4 months; maximum: 164 months). A total of 11 (34%) patients underwent adjuvant radiation, out of which 10 (91%) cases involved the knee joint and 1 (9%) case involved the hip joint. Out of all the diffuse PVNS cases in our case series, a total of 6 (19%) had local recurrence, all of which were PVNS cases involving the knee. None of the patients who were given adjuvant radiation was diagnosed with local recurrence in our case series.

Conclusion: Diffuse PVNS has a substantial local recurrence rate, particularly in the knee joint and following arthroscopic surgery. The study highlights the potential benefit of adjuvant radiotherapy in reducing recurrence. These findings underscore the importance of tailored surgical approaches and adjuvant therapies in the management of PVNS to mitigate recurrence risks. Future prospective studies are warranted to validate these results and optimize treatment protocols.