Cavitary Lung Lesion as the Initial Presentation of Diffuse Large B-Cell Lymphoma: A Case Report With Review of the Literature.

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma and may rarely present with pulmonary involvement, creating significant diagnostic challenges. We report the case of a 69-year-old man who presented with a persistent cavitary right lower lobe lung lesion initially treated as recurrent pneumonia. Despite multiple courses of antimicrobial therapy, his symptoms persisted, and extensive infectious etiology evaluation was unrevealing. Bronchoscopic biopsy ultimately demonstrated aggressive DLBCL. Subsequent evaluation revealed small bowel involvement, establishing systemic DLBCL with secondary pulmonary involvement. This case highlights an uncommon presentation of DLBCL masquerading as refractory pulmonary infection. We also review the previously reported cases of cavitary pulmonary DLBCL. Persistent cavitary lung lesions that fail to respond to appropriate antimicrobial therapy should prompt consideration of malignant etiologies and early tissue diagnosis.