Squamous cell lung cancer coexisting with pulmonary MALT lymphoma: a rare case report

Background Mucosa-associated lymphoid tissue (MALT) lymphoma is a type of non-Hodgkin lymphoma that originates from MALT, most commonly in the stomach. However, primary pulmonary MALT lymphoma is particularly rare, and concomitant squamous cell lung cancer is even rarer. Herein, we report a rare case of squamous cell lung cancer coexisting with pulmonary MALT lymphoma. Case presentation A 67-year-old elderly male presented with chest pain and was found to have a lesion approximately 32×14 mm in the left upper lung during health examination. A biopsy confirmed squamous cell lung cancer, with negative EGFR and ALK driver genes, and PD-L1 expression < 1%. ¹⁸ F-FDG-PET/CT indicated multiple mediastinal lymph node metastases. After three cycles of neoadjuvant immunochemotherapy, the patient underwent left upper lobectomy and radical lymph node dissection. Histopathological and molecular examinations confirmed that the lesion combined with a pulmonary MALT lymphoma, and the neoadjuvant therapy efficacy evaluation of pulmonary squamous cell carcinoma achieved pathological complete response (pCR). Postoperatively, the patient received only two cycles of adjuvant immunotherapy due to interstitial pneumonia. Follow-up a year post-surgery showed no signs of tumor recurrence or metastasis. Conclusion For patients with concurrent primary pulmonary lymphoma (PLL) and lung squamous cell carcinoma, there are currently no definitive treatment guidelines for this scenario. Our case suggests that the treatment strategy should prioritize lung cancer management. Further cases are needed to elucidate the underlying mechanisms and potential treatment options.