A rare case of lung squamous cell carcinoma coexisting with pulmonary MALT lymphoma presenting as a progressive pGGN

Pulmonary extranodal marginal zone lymphoma of the mucosa-associated lymphoid tissue (MALT) presenting as a progressive pure ground-glass nodule (GGN) coexisting with lung squamous cell carcinoma has not been reported. A 65-year-old male presented with a progressive lung GGN in the left upper lobe identified six and a half years ago but showed no symptoms. The patient had a history of tuberculosis, squamous cell carcinoma, and stomach MALT lymphoma. The patient was diagnosed with lung squamous cell carcinoma coexisting with pulmonary MALT lymphoma through computed tomography (CT)-guided lung biopsy. A progressive lung GGN presenting in a patient with squamous cell carcinoma does not always indicate multiple primary lung adenocarcinoma, especially when given a specific medical history. The development of MALT lymphoma in the lung presenting as GGNs suggests a possible association between these two entities.