Primary Pulmonary Plasmacytoma Presenting as Multiple Lung Nodules

To the Editor, Extramedullary plasmacytoma is a plasma cell tumor arising outside the bone marrow and usually occurs as a solitary tumor in the upper respiratory tract, such as the pharynx, paranasal sinuses, nasal cavity, or oral cavity [1]. Other cases develop in the lymph nodes, skin, gastrointestinal tract, genitourinary tract, and other regions. Primary pulmonary plasmacytomas are very rare and usually present as solitary lung nodules or masses [2]. Unusual cases manifest as diffuse pulmonary infiltration [3,4]. We describe here a unique case of primary pulmonary plasmacytoma, which presented as multiple lung nodules during regular screening in a patient with systemic lupus erythematosus. A 26-year-old woman was admitted and referred to the pulmonary service for an evaluation of multiple lung lesions on simple chest radiographs. The patient was diagnosed with systemic lupus erythematosus 11 years ago and had been treated with methotrexate, hydroxycholoroquine, and deflazacort. At the time of the systemic lupus erythematosus diagnosis, she was treated successfully for pulmonary tuberculosis with antituberculosis medication, and follow-up chest radiographs showed no active lung lesions. A chest radiograph, taken 3 months before admission as a screening for chest abnormalities, showed infiltrative lesions in both lower lung fields and focal consolidation in the right lower lobe but no specific change in her condition. Chest radiographs just before admission showed a slight aggravation of multiple patchy opacities. On admission, she presented slight sputum without other respiratory symptoms such as dyspnea or chest pain, and a review of systems was unremarkable. Vital signs were normal and there were no abnormal findings in the chest. A chest computed tomography (CT) scan revealed ill-defined nodular opacity and consolidation in both lungs (Fig. 1). Nodular lesions were scattered in both lung parenchymas and some were accompanied by ground glass opacities. A CT-guided needle aspiration biopsy specimen was nondiagnostic and, therefore, a subsequent surgical wedge resection via a thoracotomy was performed. The biopsy samples showed two relatively poorly demarcated round grayish white colored masses measuring 1.2 and 3 cm in diameter, respectively. A microscopic examination demonstrated diffuse infiltration of plasma cells (Fig. 2A), which were positive for lambda chain immunohistochemical staining (Fig. 2B). Serum protein and albumin levels were 8.2 g/dL and 3.4 g/dL, respectively. An electrophoretic analysis of serum proteins showed decreased albumin and an increased gamma globulin region without the M component. Serum immunoelectrophoresis detected no abnormal findings. Urine protein electrophoresis and immunoelectrophoresis were normal. An examination of serum