Plasmacytoma of the lung: an indolent disease resistant to conventional myeloma treatment: report of a case.

Solitary lung plasmacytoma is a rare form of plasma cell tumors. The case of a 56-yr-old man is presented, who had a massive tumor of the right pulmonary apex. Percutaneous transthoracic lung biopsy demonstrated a tumor-cell population consisting of mature plasma cells, proplasmacytes, and rare plasmablasts. Immunohistochemically, the cells were CD79a+, kappa+, cyclin D1-, p53-, MDR-. Proliferative index was low (number of Ki-67+ tumor cells was 8%). Serum and urine immunoelectrophoresis did not show the presence of paraprotein. Screening for multiple myeloma with skeletal X-ray survey and bone marrow biopsy were negative. Radiotherapy and chemotherapy with alkylating agents were ineffective. However, the course of the disease is indolent and the patient is well, alive, and with no signs of multiple myeloma >5 yr after the diagnosis was established. Some pathogenetic aspects of tumor resistance to conventional myeloma treatment in this case are discussed.