Hypermetabolic Subserosal Uterine Leiomyoma With Synchronous Atypical Multiple Myeloma Mimicking Ovarian Malignancy With Multiple Bone Metastases on 18F-FDG PET/CT.

Subserosal cystic myoma with intense FDG uptake can resemble malignant cystic ovarian tumor and may lead to a false-positive diagnosis. A 49-year-old woman presented with chest pain for 4 months, and the initial chest CT showed multiple bone lesions. 18F-FDG PET/CT revealed not only multiple osteolytic lesions with FDG uptake but also a highly FDG-avid mass abutting the right side of the uterus. Ovarian malignancy with multiple bone metastases was considered initially. Subsequent biopsy confirmed multiple myeloma, and a subserosal uterine myoma was diagnosed by transvaginal sonography.