Primary Pulmonary Involvement in Mucosa-associated Lymphoid Tissue Lymphoma

Pulmonary nodules have a broad differential diagnosis with primary lung cancer, lung metastases, benign tumors, carcinoid tumors, and infectious granulomas as their common cause. While relatively rare, pulmonary lymphoproliferative disorders such as primary pulmonary lymphomas, primary pulmonary plasmacytomas, secondary lymphomas involving the lung, multiple myeloma involving the lung, leukemias involving the lung should be considered in these patients presenting with lung nodules. Primary pulmonary non-Hodgkin's lymphoma (NHL) is an extremely rare lung tumor accounting for 0.4% of all lymphomas. Mucosa-associated lymphoid tissue (MALT) lymphoma accounts for about 70%-90% of all primary pulmonary lymphomas, constituting less than 0.5% of all the lung neoplasms. Though it usually remains localized, it is a clonal B-cell neoplasm with a potential for systematic spread and transformation to an aggressive B-cell lymphoma. We hereby discuss the case of a 66-year-old woman with primary pulmonary MALT lymphoma.