[Pigmented villonodular synovitis of the knee].

This case report is concerned with a 30 year old patient diagnosed with pigmented villonodular synovitis (PVNS) in the knee. The patient underwent an orthopedic surgical operation to remove the lesions. PVNS is a rare proliferative disorder, mostly benign and affecting the knee; its aetiology remains unclear. It represents a medical challenge because of non-specific symptoms that delay the diagnosis with a very high rate of recurrence. MRI imaging is necessary to explore the lesions, but the final diagnosis can only be made after anatomopathologic analysis of the excised lesions. When multiple lesions are present, the treatment consists of their excision by arthrotomy, or by arthroscopy if the disease is localized.