A 79-year-old woman presented with a pulmonary nodule, which was incidentally found during regular health examination. Chest computed tomography revealed a solitary nodule of 1.4 cm in diameter located in the upper lobe of the right lung (A). Percutaneous needle biopsy of the nodule revealed extensive infiltration of plasma cells (B, C). Immunohistochemically, the cells were positive for CD138 and were restricted to kappa light chain (D). Complete blood count, routine chemistry (including BUN, creatinine and calcium) and urine analysis were nonspecific. Serum and urine protein electrophoresis and immunofixation did not show the presence of paraprotein, and serum kappa and lambda free light chains were within normal limits. Bone marrow plasma cells were less than 1%. Skeletal X-ray survey was negative. She was diagnosed with solitary pulmonary plasmacytoma and was placed on curative radiotherapy (36 Gy over 4 weeks). This case illustrates that plasmacytoma can be presented as a solitary pulmonary nodule.