Expression of cell cycle-related gene products in different forms of primary versus recurrent PVNS

Expression patterns of cell cycle regulating gene products and Ki-67 in proliferating synovial cells of primary and recurrent pigmented villonodular synovitis (PVNS) in localized and diffuse lesions were examined by immunohistochemistry. Alterations of cell cycle-related proteins were seen in 98.7% of analyzed lesions. Both RB- and p53 pathways play a role in cell cycle dysregulation in PVNS. The RB pathway was more frequently altered in primary disease, while alterations of the p53 pathway seemed to be more important in recurrent lesions, regardless of the histomorphological type of disease. Ki-67 proliferation rate was elevated in recurrent tumors.