[Pulmonary mucosa-associated lymphoid tissue lymphoma concurrent with lung squamous cell carcinoma: a case report and literature review].

To explore the clinical manifestations, imaging features, pathological features, diagnosis and treatment of pulmonary mucosal-associated lymphoid tissue(MALT)lymphoma concurrent with lung squamous cell carcinoma, and to improve the understanding of this disease. Using "Pulmonary mucosa-associated lymphoid tissue, squamous cell carcinoma" as the search term, from January 1, 1983 to August 31, 2020, a total of 3 cases were retrieved in the PubMed database. In the Wanfang database, using "Lung mucosa-associated lymphoid tissue, lung squamous cell carcinoma" as the search term, from January 1, 1990 to August 31, 2020, a total of 1 related document was retrieved. In the CNKI database, "(lung) mucosa-associated lymphoid tissue lymphoma, (lung) squamous cell carcinoma" was used as the search term, and no relevant case reports were retrieved. A 64-year-old man was admitted to the hospital because of chest tightness and shortness of breath for 10 days, cough and fever for one day. Enhanced CT of the chest showed a soft tissue mass shadow in the right lower hilar area, with obstruction of the adjacent bronchus, and local mild enhancement, suggesting of right lower lung cancer. In addition, the CT scan also showed consolidated shadows in the lower lobes of both lungs, scattered nodules, multiple lymphadenopathy in the mediastinum, and a small amount of pleural effusion on the right. Under bronchoscopy, a cauliflower-like neoplasm was seen at the opening of the lower right basal section, about 7 mm×8 mm, and biopsy showed that part of the mucosal structure was destroyed, with disappearance of the squamous epithelial layer, and the nuclei were large and deeply stained, and some were distributed in nests, with poor keratinization and a small amount of necrosis, and fibrous tissue reaction. Immunostaining revealed that the tumor was positive for p40, CK5/6 and EGFR and negative forTTF-1, NapsinA, PD-L1, p53, with about 30% Ki-67 positive cells. A puncture biopsy of the right lower lobe showed that the alveolar cavity was filled with nested lymphoid cells, consisting of small lymphocytes, central cell-like cells and monocyte-like cells, with occasionally large cells. Immunostaining revealed CD, CD, scattered CD+, Bcl2+, SMA vascular+, Bcl6-, CK-, CD10-, CyclinD1-, with about 3% Ki-67 positive cells. The histopathological examinations confirmed the diagnosis of mucosal-associated lymphoid tissue extranodal marginal zone lymphoma(MALT lymphoma),and lung squamous cell carcinoma. Pulmonary mucosa-associated lymphoid tissue lymphoma complicated with lung squamous cell carcinoma is rare and easy to be missed and misdiagnosed. Chest CT imaging shows single or multiple nodules, mass shadows or consolidation, often accompanied by air-bronchial signs in the lesion, bronchiectasis, ground glass density around the lesion, hilar and mediastinal lymphadenopathy. Occasionally, pleural effusion can be seen. Lung biopsy is the gold standard for diagnosis.