Subcutaneous pigmented villonodular synovitis caused by portal contamination during knee arthroscopy and open synovectomy.

The etiology of pigmented villonodular synovitis (PVNS) is not clear. Researchers have suggested that localized nodular synovitis is an inflammatory process, but more recent studies tend to describe the lesion as benign synovial neoplasm with the potential of local recurrence. Although the theoretical risk of secondarily seeding the remainder of the knee is evident, this is the first report of a subcutaneous PVNS caused by portal contamination during knee arthroscopy and open synovectomy. It supports a neoplastic origin of this lesion.