A80-4-10 When a Nodule Isn’t Just a Nodule: Pulmonary Involvement in Diffuse Large B-cell Lymphoma

Abstract Introduction A lung nodule often triggers thoughts of infection or metastasis, but sometimes it hides something unexpected. Diffuse large B-cell lymphoma (DLBCL) is the most common form of non-Hodgkin lymphoma, accounting for roughly one-third of all cases. Roughly 40% of patients have extra-nodal disease, most often in the gastrointestinal tract, bone marrow, or central nervous system. Pulmonary involvement on the other hand, is rare. Because these lesions can mimic infection, inflammation, or metastatic cancer, diagnosis can be challenging. This case describes an unusual presentation of stage IV DLBCL with both pulmonary and splenic involvement, revealing a subtle yet important diagnostic dilemma in pulmonary medicine. Case Description A 79-year-old woman with diabetes, anemia, depression, bradycardia with a pacemaker, mild cognitive impairment, and prior transcatheter aortic valve replacement (TAVR) was evaluated for persistent memory problems. Brain MRI showed age-related changes and worsening small vessel disease. A screening chest x-ray, done because of her pacemaker, unexpectedly showed a right lower lobe opacity. She reported a two-month history of cough and exertional dyspnea but denied fever, weight loss, or night sweats. CT chest revealed a 2.2 cm right lower lobe nodule, a 1.4 cm spiculated right middle lobe nodule, and several hypodense splenic lesions up to 4.1 cm. PET-CT showed intense FDG uptake in the right lower lobe nodule (SUV 7.2) and the spleen, suggesting systemic disease. Bronchoscopy with biopsy showed only inflammation. A subsequent image-guided splenic biopsy confirmed diffuse large B-cell lymphoma, germinal center type, consistent with stage IV disease involving the lung. After multidisciplinary discussion and review of options, she elected comfort-focused care. Discussion Pulmonary involvement in DLBCL is rare and often misdiagnosed as infection or metastasis. Imaging findings are nonspecific, and bronchoscopic biopsies frequently yield non-diagnostic results. PET-CT plays a central role in identifying active disease and directing biopsy. This case underscores the importance of maintaining a broad differential when evaluating unexplained pulmonary nodules, even in the absence of constitutional “B” symptoms. Learning Point When a lung nodule doesn’t fit typical infectious or malignant patterns, consider extra-nodal lymphoma. Multidisciplinary collaboration among pulmonology, radiology, pathology, and oncology is essential for timely diagnosis and patient-centered care. Disclosure AI assistance was used for drafting and language refinement. All case content and interpretations were written and confirmed by the authors. This abstract is funded by: None