We report a 58-year-old male patient presenting with a 1-year history of presternal swelling and pain. Plain radiography revealed increased soft tissue density anterior to the body of the sternum, which showed cortical sclerosis. Computed tomography (CT) demonstrated ring-enhancing hypodense soft tissue masses surrounding the sternum, whose anterior and posterior cortices were markedly thickened. On three-phase technetium bone scintigraphy, the left side of the sternum showed increased radiotracer uptake and the central part of the bone was photopenic. The bone marrow of the sternum and peristernal soft tissue lesions were hypo- and hyperintense on T1- and T2-weighted magnetic resonance (MR) images, respectively, and showed marked enhancement postgadolinium. Treatment included both surgical intervention and medical therapy.