Patello-femoral joint pain due to unusual location of localised pigmented villonodular synovitis-a case report.

Localised pigmented villonodular synovitis (PVNS) is a rare condition usually affecting the knee. It can be a difficult condition to manage with an average delay in diagnosis of 4.4 years. We describe a case of a localised PVNS lesion interposed between the patello-femoral joint, presenting as 'anterior knee pain'. To our knowledge this has not previously been reported. The lesion was completely excised at arthroscopy resulting in complete resolution of symptoms. Solitary lesions of PVNS should also be considered in the differential diagnosis of unexplained 'anterior knee pain'.