Combined type of nodular and diffuse forms of pigmented villonodular synovitis in a single knee joint of a child.

There are two types of pigmented villonodular synovitis (PVNS), nodular and diffuse. Two types generally do not coexist, and only one type usually occurs. This report presents a rare case of 12-year-old boy with combined type of PVNS in the knee joint who was treated arthroscopically.