Intranuclear inclusions in a case of pigmented villonodular synovitis of the ankle

Pigmented villonodular synovitis (PVNS) is a proliferative disorder of the synovial lining of the joints. Although the cytological findings of this disorder have been described in the literature, there is no mention of intranuclear cytoplasmic inclusions in this entity. A 65-yr-old woman presented with a painful swelling on the ankle. In addition to other characteristic findings of PVNS, we found the presence of intranuclear cytoplasmic inclusions in the fine-needle aspiration (FNA) smears. The characteristic cytological findings of abundant mononuclear cells occurring singly and in papillary clusters, multinucleated giant cells, and hemosiderin deposition should aid in the diagnosis of PVNS and in its differentiation from melanoma and other soft tissue sarcomas, even in the presence of uncommon features such as intranuclear inclusions.