[Villonodular synovitis of the knee: about 20 cases].

Pigmented villonodular synovitis (PVNS) is a rare benign proliferation of synovial joints, serous bursa, tendinous sheaths of unknown etiopathogeny. We here report 20 cases of PVNS of the knee recorded at the Avicenne Military Hospital, Marrakech over a period of 9 years, from January 2000 to December 2009. This study aimed to identify the specific features of this lesion and to examine its anatomoclinic and prognostic aspects. Annual incidence was 2.2 cases per year: 15 men and 5 women. The average age was 32.5 years. It occurred in the right-hand in 55%, 18 patients had monoarticular presentation of the disease while 1 patient had biarticular presentation of the disease. 80% of cases had pain and swelling, palpable mass was detected in 1 case, meniscal syndrome in 1 case, monoseptic arthritis in 3 cases while popliteal cyst in 2 cases. 14 cases (70%) had diffuse involvement, 6 cases had localized involvement. MRI was evocative in 3 patients out of 5; 2 patients underwent diagnostic arthroscopy. Diagnosis was based on anatomo-pathological examination. Treatment was based on subtotal synovectomy in 15 cases and on tumor excision in patients with localized involvement. 2 cases with osteocartilaginous destruction underwent arthroplasty. Patients' evolution was marked by 2 diffuse recurrences after a mean follow-up of 3-7 years. 3 patients had stiffness associated with quadriceps atrophy, therefore arthrolysis was performed. One case of histologically confirmed PVNS had proved to be a monophasic synovial sarcoma invading the bone 5 months after total synovectomy. Hence, the indication for amputation.