Review Question - QID 3297

The history, radiographs, CT scan, MRI, and histology slide are consistent with a diagnosis of giant cell tumor of the sacrum. Outside the appendicular skeleton, the sacrum is a common location for giant cell tumor of bone. The radiographs and CT scan show a well defined lytic lesion. The characteristic MRI signal pattern of a lesion which isn't too bright nor too dark is seen on T2 and T1 MRI. This MRI signal is characteristic for giant cell tumor, lymphoma, and Ewing's sarcoma. The histology specimen shows multinucleated giant cells on a mononuclear stromal background. While the MRI appearance may be suggestive of either giant cell tumor, lymphoma, or Ewing's sarcoma, the histology specimen is classic for giant cell tumor. Histology slides for lymphoma and Ewing's sarcoma are shown in illustrations A and B. Note the classic Reed-Sternberg cells of lymphoma with granular cytoplasm and a eosinophilic nucleolus and the small round blue cells of Ewing's sarcoma.