Incidental finding of an 11C-acetate PET-positive multiple myeloma

Multiple myeloma is a malignancy of plasma cells. The 18F-FDG PET findings of multiple myeloma have been reported previously. However, the 11C-acetate PET findings have not been clarified. Here, we report a case of multiple myeloma detected with 11C-acetate PET in a 51-year-old male patient with known hepatocellular carcinoma. The patient was admitted for management of a pathologic fracture of the right tibia. Imaging workup including X-ray, magnetic resonance image, bone scintigraphy; 18F-FDG led to a suspicion of metastatic bony lesions. Further, these lesions showed increased uptake on 11C-acetate PET. Wide excision of the right tibia was performed, and histopathological examination of the lesion confirmed multiple myeloma. This case illustrates the characteristic 11C-acetate PET findings of multiple myeloma.