Ossified soft tissue recurrence of giant cell tumor of the bone: four case reports with follow-up radiographs, CT, ultrasound, and MR images.

Giant cell tumor (GCT) of the bone is a benign tumor with a high incidence of recurrence. The majority of recurrence occurs in the bone, typically where curettage was performed previously. Soft tissue recurrence is much less common and often shows ossification at the periphery of the soft tissue mass. We report four cases of ossified soft tissue recurrence of giant cell tumor of the bone after surgery at follow-up examination using plain radiography, ultrasound, CT, and MR imagings. Imaging findings of soft tissue recurrence with peripheral or central ossification were reviewed with pathologic correlation. To the best of our knowledge, this is the first report to describe soft tissue tumor recurrence with ossification illustrated and monitored at various imaging modalities over an extended follow-up period.