Solitary Plasmacytoma of the Sternum
A 62-year-old female patient was referred by a regional hospital to department of thoracic and cardiovascular surgery because of a mass in her sternum. At presentation, the patient had no disease other than hypertension. She had received calcium channel blocker therapy for her hypertension at a regional hospital for >3 years prior to this presentation, and her blood pressure was well controlled. She was a housewife by occupation and did not have any specific family history of cancer. Her blood pressure was 118/72 mmHg; pulse rate, 64 beats/min; respiratory rate, 16/min; and body temperature, 36.7℃. A physical examination revealed a bulging mass in the mid-sternum and mild tenderness around the mass. Laboratory tests revealed white blood cell, 7,800/µL and hemoglobin, 13.2 g/dL. However, other initial laboratory test results were noted to be within the normal range. Plain chest radiographs, including the sternum lateral view, revealed a sternal mass. Chest computed tomography (CT) revealed a sternal mass 4×4 cm in size containing an osteoclastic lesion in the body of the sternum. A further evaluation using whole body bone scintigraphy revealed a focus of mild increased uptake in the sternum with a bone-to-soft tissue ratio of 2.34:1, and no evidence of a hot uptake lesion was noted in the other bony areas. Positron emission tomography-CT (PET-CT) with 18-fluro-deoxyglucose showed a mildly hypermetabolic mass in the body of the sternum with a standard uptake value of 4.6 but did not detect any other lesions or distant metastasis other than a sternal lesion (). Under localized anesthesia, an incisional biopsy was performed, which showed atypical plasma cells having centrally or eccentrically located ovoid nuclei and eosinophilic cytoplasm. These histological findings indicated a plasma cell neoplasm suggestive of solitary plasmacytoma of the sternum (). Immunohistochemical studies of the specimen showed positive lambda chains and negative kappa chains, but the results were all negative for the clusters of differentiation 99, neuron specific enolase, S-100, cytokeratin, and desmin. Further studies were performed to differentiate solitary plasmacytoma of sternum from multiple myeloma (MM). Complete skeletal radiographs, including the humerus and femur, revealed negative results and no evidence of other osteolytic lesions. In addition, laboratory studies, including complete blood cell count, serum electrophoresis, 24-hour urine protein electrophoresis, alkaline phosphatase, lactic dehydrogenase, C-reacting protein, serum calcium, and phosphate showed normal values and no evidence of anemia, hypercalcemia, or renal involvement suggestive of systemic myeloma. Immunofixation of serum and concentrated urine exhibited no monoclonal proteins.\nMultidisplinary approaches for further management, including radiotherapy, surgical management with wide resection, and chemotherapy, were discussed, and radiation therapy was determined to be the best choice for the patient. The patient was transferred to the department of hemato-oncology and radiation oncology.