Ultrastructural features of giant cell tumors in Paget's disease

Giant cell tumor is a rare complication of Paget's disease. This association is especially notable in patients originating from Avellino, Italy. Many types of evidence point to a viral etiology for Paget's disease and giant cell tumors arising in it. Three patients who had giant cell tumors and Paget's disease were studied. Two of the patients have a connection to Avellino (one was born in Avellino, and one descended from natives of Avellino). Distinctive light microscopic and ultrastructural features common in these three patients were identified. In all three patients, the giant cell tumors had peculiar irregular aggregates of microfilaments of uncertain genesis. The possibility that these reflect viral infection is discussed.