Coexistence of diffuse large B-cell lymphoma and lung adenocarcinoma in one lymph node: a case report and literature review.

Older men demonstrate heightened susceptibility to both diffuse large B-cell lymphoma (DLBCL) and lung adenocarcinoma. Nevertheless, synchronous presentation of DLBCL and adenocarcinoma within the same lymph node remains exceptionally rare. A 70-year-old Chinese man presented with a 1-year history of a productive cough with white sputum, progressive shortness of breath, and chest tightness. The patient received four cycles of R-CHOP immunochemotherapy directed at the DLBCL. Cervical lymphadenopathy decreased markedly after treatment, and no obvious lymphoma progression was documented during the 5-month follow-up. No specific treatment was administered for the lung adenocarcinoma. This unusual coexistence of DLBCL and metastatic carcinoma poses a significant diagnostic challenge, underscoring the critical need for precise early histopathological evaluation to guide optimal therapeutic intervention.