Clinical outcomes of surgery followed by adjuvant radiotherapy for diffuse-type tenosynovial giant cell tumor (pigmented villonodular synovitis): a retrospective case series

Diffuse-type tenosynovial giant cell tumor (TGCT), formerly known as pigmented villonodular synovitis (PVNS), is a rare locally aggressive synovial tumor with a high risk of recurrence after surgery. Complete resection is often challenging in diffuse lesions, and the benefit of adjuvant radiotherapy for improving local control has not been well established.Therefore, we retrospectively evaluated the clinical outcomes of surgery followed by postoperative radiotherapy in patients with diffuse-type TGCT. We retrospectively reviewed the records of 17 patients with diffuse-type TGCT who received postoperative radiotherapy at the Second Affiliated Hospital of Zunyi Medical University between March 2019 and October 2025: 14 received adjuvant radiotherapy after the index operation and 3 received salvage radiotherapy after recurrence. In seven patients the index operation had been performed at another institution before referral. Local recurrence, symptom relief, functional recovery, and treatment-related adverse events were assessed through outpatient follow-up and telephone interviews. Recurrence was defined as histopathological confirmation after reoperation or recurrent clinical symptoms supported by MRI findings. Joint function was assessed using the International Knee Documentation Committee (IKDC) score, Mayo Elbow Performance Score (MEPS), or Mayo Hip Score (MHS), according to the involved joint. Radiotherapy-related toxicity was graded according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Because these joint-specific instruments are not directly interchangeable and only one hip and one elbow case were included, statistical analysis was restricted to the 13 patients with unilateral knee involvement, whereas the remaining four patients (one hip case, one recurrent elbow case, and two recurrent knee cases, including one patient with bilateral knee involvement) were reported descriptively. As of August 2026, the follow-up period for the entire cohort ranged from 10 to 73 months, with a median of 35 months and a mean of 41 months. Among the 14 patients who received postoperative adjuvant radiotherapy, follow-up ranged from 10 to 73 months (mean, approximately 39 months; median, 35 months), and none developed local recurrence. This group included one patient with hip involvement, who remained recurrence-free at 59 months of follow-up. Among the three patients who received salvage RT after recurrence, none developed a further local recurrence after RT (follow-up, 25–66 months). The third patient developed local recurrence 16 months after the initial surgery, experienced a second local recurrence 3 weeks after a second surgery, received adjuvant radiotherapy after a third surgery, and remained recurrence-free at 66 months of follow-up. In the knee cases included in the SPSS analysis, joint function scores improved significantly after treatment compared with baseline ( p < 0.001), and pain scores also decreased significantly ( p = 0.002). In exploratory subgroup analyses stratified by surgical approach, sex, body mass index, and RT dose, no statistically significant differences were observed (all p > 0.05). Treatment-related adverse events were mostly mild and manageable, and no grade ≥ 3 toxicities were observed. In this descriptive, non-comparative retrospective case series, surgery followed by RT was associated with favorable local control, acceptable toxicity, and improved joint function in patients with diffuse-type TGCT. However, because all patients received surgery followed by RT and no surgery-only control group was available, the independent contribution of RT to these outcomes cannot be determined. The findings should therefore be interpreted as hypothesis-generating and warrant confirmation in larger, prospective, comparative studies.