[Pigmented Villonodular Synovitis: a diagnostic challenge. Review of 28 cases].

OBJECTIVE: Pigmented Villonodular Synovitis (PVNS) is a benign and uncommon clinical entity, characterized by excessive proliferation of synovial membrane of joints, tendon sheaths and bursas. The objective of this study was to evaluate demographic and clinical parameters, diagnostic and treatment procedures and the outcome of 28 patients with PVNS.
MATERIAL AND METHODS: Retrospective study of the histologically proven cases of PVNS, diagnosed between January 1998 and April 2010 in the Orthopaedics Department of Coimbra University Hospital. Clinical data were reviewed for each patient and the following parameters were evaluated: gender, age at diagnosis, initial clinical symptoms and site of onset, symptom duration, main imaging findings (x-ray and magnetic resonance imaging of the involved structure), histological features of the lesion, treatment, follow-up duration, evidence of recurrence and time between surgery and recurrence.
RESULTS: A total of 28 patients with histologically proven PVNS were included. The majority of patients were female (53.6%) and the mean age at the time of diagnosis was 39.2 ± 19.1 years (mean ± SD). The time between onset of symptoms and diagnosis was un- known in one patient and, in the other 27 patients, mean delay in diagnosis was 24.4 ± 20.5 months (mean ± SD). The knee was the most frequently affected site (75% of the cases). Pain and progressive local swelling sensation were the most frequent symptoms at onset (in 82.1% and 71.4% of the cases, respectively). Joint x-ray identified abnormalities in only 17.8% of the patients. Magnetic resonance imaging (MRI) of the affected structure identified the presence of synovial membrane proliferation in all cases and extra-articular extension of the lesion and bone erosions in 39.1% and 34.8%, respectively. Diagnosis was histologically proven in all cases (27 with synovial joint origin and 1 with tenosynovial origin). Subtotal synovectomy, total synovectomy, local excision of the lesion, synovectomy associated with arthroplasty and synovectomy associated with arthrodesis were performed in 53.6%, 21.4%, 10.7%, 7.1% and 3.6% of the cases, respectively. Local recurrence occurred in 25% of the patients, with a mean time of recurrence of 60.8 months after surgery.
CONCLUSION: In PVNS patients, the non-specific symptoms often contribute to a delay in establishing a diagnosis. As in the majority of the reported studies, in this study the knee was also the most commonly affected articular site. Although the x-ray of the affected joint revealed abnormalities in just a few number of patients,MRI identified the presence of synovial membrane proliferation in all cases, proving its value in the diagnostic approach to this entity. However, only the histological study of the lesion allows establishing a definitive diagnosis.