Primary Pulmonary Non-Hodgkin Lymphoma: A Report of Two Cases and a Review of the Literature Emphasizing the Role of Radiotherapy.

Primary pulmonary non-Hodgkin lymphoma (PPL) is a rare malignancy most commonly presented as indolent marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) or bronchus-associated lymphoid tissue (BALT). Aggressive subtypes of PPL, such as diffuse large B-cell lymphoma (DLBCL), occur less frequently. Diagnosis and workup require tissue biopsy, immunophenotyping, and cross-sectional imaging, often supplemented by positron emission tomography (PET)/computed tomography (CT) for staging and treatment planning. Radiation therapy or radiotherapy (RT) is a cornerstone in managing localized, indolent PPL, offering durable local control with minimal toxicity. Modern involved-site RT (ISRT) techniques deliver radiation in conventional fractionation schedules, precisely targeting pulmonary lesions while sparing surrounding lung and mediastinal structures. RT can be used alone for early-stage disease or following systemic therapy for residual or refractory lesions. The cases in this report highlight the importance of histology-driven, individualized treatment planning and the pivotal role of RT in achieving optimal outcomes in this rare malignancy.