What is the recommended initial treatment for polyvillonodular synovitis (PVNS) of the ankle?

Treatment of Pigmented Villonodular Synovitis (PVNS) of the Ankle

For localized PVNS of the ankle, perform arthroscopic partial synovectomy without adjuvant radiotherapy; for diffuse PVNS confined to the joint, perform arthroscopic comprehensive synovectomy followed by adjuvant external-beam radiotherapy; and for diffuse PVNS with extra-articular extension, perform combined arthroscopic and open synovectomy followed by adjuvant radiotherapy. 1

Initial Diagnostic Approach

• Obtain MRI imaging, which is essential for diagnosis, treatment planning, and distinguishing localized from diffuse disease 2
• Confirm diagnosis with histopathologic examination of synovial tissue 2, 3
• Assess for extra-articular extension to tendon sheaths, which significantly impacts treatment strategy and recurrence risk 3

Treatment Algorithm Based on Disease Extent

Localized PVNS (Nodular Form)

• Perform arthroscopic partial synovectomy as definitive treatment 1, 3
• Radiotherapy is not indicated for localized disease 3
• Expect 100% good-to-excellent results with this approach 3
• Recurrence is rare with complete excision of the localized lesion 2

Diffuse PVNS Limited to Intra-Articular Synovium

• Perform arthroscopic comprehensive synovectomy addressing all accessible synovial surfaces 3
• Follow with adjuvant external-beam radiotherapy at low doses (2,600 cGy total) 4, 5
• This combination achieves 100% good-to-excellent results and significantly reduces recurrence compared to synovectomy alone 4, 3
• The radiotherapy should be administered postoperatively to treat microscopic residual disease in inaccessible areas 4

Diffuse PVNS with Extra-Articular Extension

• Perform combined arthroscopic and open synovectomy to access both intra-articular and extra-articular disease 3
• The open approach should include takedown and repair of anterior meniscal attachments and direct entry into posterior spaces through medial and lateral femoral capsular attachments 6
• Follow with adjuvant external-beam radiotherapy 3, 5
• Consider cryosurgical adjuvant spray on all non-cartilaginous surfaces during open synovectomy to improve local control 6
• Expect 73% good-to-excellent results, with higher recurrence rates (approximately 31%) compared to intra-articular disease only 3

Critical Management Principles

Early surgical intervention is the only recommended curative approach, as delayed treatment leads to secondary bony lesions, joint destruction, and worse outcomes 2. The decision between arthroscopic versus open approach depends on disease extent and presence of extra-articular involvement 2.

Timing of Radiotherapy

• Radiotherapy should be administered as primary adjuvant therapy at initial treatment, not reserved only for recurrence 4, 5
• Low-dose external-beam radiation (2,600 cGy) in anti-inflammatory doses produces good results without significant complications 4
• Long-term follow-up (8 years) demonstrates no evidence of recurrence when radiotherapy is used adjunctively 5

Systemic Therapy Considerations

For patients with symptomatic diffuse disease where surgery is not optimal or for recurrent disease after surgery:

• CSF-1 targeted therapies (pexidartinib, imatinib, nilotinib, vimseltinib) can be used to improve symptoms and function 1
• Pexidartinib is the only FDA-licensed treatment (in USA only) for tenosynovial giant cell tumor (the current terminology for PVNS) 1
• These agents are particularly relevant when surgery carries high risk of functional loss or for multiply recurrent disease 1

Common Pitfalls to Avoid

• Do not perform incomplete synovectomy for diffuse disease, as this leads to high recurrence rates requiring repeat procedures 2, 4
• Do not delay radiotherapy until recurrence occurs; adjuvant radiotherapy at initial treatment significantly reduces recurrence 4, 5
• Do not use arthroscopy alone for diffuse PVNS with extra-articular extension, as this will miss disease in tendon sheaths and lead to recurrence 3
• Recognize that patients with extra-articular extension have inherently higher recurrence risk (31%) even with optimal treatment 3

Monitoring for Recurrence

• Follow patients with serial MRI examinations to detect early recurrence 5
• Recurrent disease presents with return of pain, swelling, and erythema 4
• If recurrence occurs after combined synovectomy and radiotherapy, repeat arthroscopic synovectomy can be performed safely, though fibrous bands and tissue reorganization from prior radiotherapy will be encountered 4
• Consider systemic CSF-1 targeted therapy for multiply recurrent disease 1