A case of duodenal involvement of multiple myeloma imaged by positron emission tomography with 18F-fluorodeoxyglucose.

A 61-year-old woman had been treated for multiple myeloma for 4 years when she developed abdominal pain. Ultrasonography and computed tomography revealed a tumor in the abdomen. Positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) showed increased FDG uptake in the tumor. In previous bone marrow lesions, which were in clinical remission after chemotherapy and radiotherapy, abnormal FDG uptake was not recognized. Pathological examination after surgery revealed the tumor to be a plasmacytoma of the duodenum. Plasmacytoma of the duodenum is rare but can be seen during the clinical course of multiple myeloma. A few reports have described FDG PET findings of plasmacytoma. Those previous reports and our present case suggest a potential value of FDG PET in the evaluation of multiple myeloma.