A80-4-49 When the Lungs Become the Target: A Rare Presentation of Pulmonary Diffuse Large B-Cell Lymphoma

Abstract Background Pulmonary involvement in diffuse large B-cell lymphoma (DLBCL) is uncommon and often presents with non-specific respiratory symptoms or radiologic findings that mimic infection, interstitial lung disease, or metastatic carcinoma. Only 3-5% of systemic DLBCL cases show overt pulmonary manifestations. Because pulmonary disease may occur at any stage, timely recognition is critical. This case illustrates the diagnostic challenge and clinical impact of secondary pulmonary DLBCL. Case Presentation A 71-year-old Caucasian male with coronary artery disease, diabetes mellitus type 2, dyslipidemia, hypertension, and known DLBCL presented with cough, dyspnea, fever, and chills. On admission, he was tachypneic, hypoxic, and in mild respiratory distress. He also reported an unintentional 20-lb weight loss over three months. CT thorax revealed a left lung mass that had enlarged since previous CT scan, associated with progressive mediastinal lymphadenopathy and a new loculated left pleural effusion. The mass had a solid component. The patient was initially treated for pneumonia and started on oxygen via nasal cannula at 3 L/min. Despite aggressive therapy, symptoms worsened with persistent fever, cough, and tachypnea. A multidisciplinary team including oncology, pulmonology, infectious disease, and interventional radiology was consulted. CT-guided lung biopsy confirmed diffuse large B-cell lymphoma. Intervention and Outcome Following biopsy confirmation, the patient was initiated on Pola-R-CHP (polatuzumab vedotin, rituximab, cyclophosphamide, doxorubicin, and prednisone) chemotherapy and completed three inpatient doses, with a plan for six total. After the first cycle, he noted improvement in dyspnea, resolution of night sweats, and increased appetite. The patient also remained on prophylactic antibiotics during hospitalization. Discussion Pulmonary DLBCL is a rare but clinically significant manifestation of systemic lymphoma. Its presentation often overlaps with infectious or inflammatory lung disease, leading to delayed diagnosis. In this patient, non-resolving pneumonia with progressive imaging findings and “B” symptoms prompted further evaluation and biopsy, confirming relapse. Multidisciplinary collaboration was crucial for diagnosis. Early initiation of Pola-R-CHP led to marked clinical improvement, underscoring that timely recognition and therapy can achieve favorable outcomes. Persistent pulmonary infiltrates in patients with lymphoma should prompt evaluation for relapse. Conclusion Pulmonary involvement by DLBCL, though rare, should be considered in patients with unexplained or non-resolving pulmonary infiltrates. Early tissue diagnosis and multidisciplinary management are key to improved outcomes. This abstract is funded by: None