Localized pigmented villonodular synovitis presenting as a locked knee: a report of three cases and a review of the literature

We report three cases of pigmented villonodular synovitis (PVNS), which presented with a locked knee in the absence of significant trauma. After clinical examination all patients were strongly suspected to have a mechanical derangement of the knee. Two patients underwent arthroscopic resection of the mass which on histology proved to be PVNS, one patient needed a small arthrotomy to remove the PVNS mass.