Solitary Plasmacytoma of the Sternum Mimicking Bone Metastasis in a Patient with a History of Breast Cancer Evaluated by F-18-FDG PET/CT

A 65-year-old woman with a history of breast cancer (stage T2N0M0 treated with left breast conservative therapy 7 years previously followed by hormone therapy) underwent fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (F-18-FDG PET/CT) for restaging due to increased serum tumour markers levels (CA15-3, 37 U/ml and CEA, 8 ng/ml). The patient presented thoracic pain before performing F-18-FDG PET/CT. PET/CT demonstrated an area of increased F-18-FDG uptake corresponding to an osteolytic lesion occupying the upper sternum suspicious for bone metastasis (Fig. 1). No other areas of abnormal F-18-FDG uptake were detected in the rest of the body. Based on this PET/CT finding, the patient performed biopsy of the sternal lesion. Histology demonstrated the presence of a sternal plasmacytoma and the patient was addressed to radiation therapy. The role of F-18-FDG PET/CT in patients with multiple myeloma is well known [1–4], whereas only some articles evaluated the usefulness of this method in patients with solitary plasmacytomas [5, 6]. In particular, F-18-FDG PET/CT may be useful in demonstrating the evolution of solitary plasmacytomas in multiple myeloma [7]. In our case F-18-FDG PET/CT was useful in detecting a solitary plasmacytoma of the sternum mimicking bone metastasis in a patient with history of breast cancer, correctly addressing to further histological evaluation.