Abstract
A 69-year-old man with systemic sclerosis and interstitial pneumonia presented with an abnormal shadow in the right upper lung lobe. A thoracoscopic needle biopsy was performed on the right upper lobe lesion, and Mycobacterium malmoense was identified by 16S rRNA and rpoB gene sequencing. Surgical treatment was performed to obtain a radical cure, and lung squamous cell carcinoma and M. malmoense infection were detected in the resected specimen. We herein report the first case of the successful treatment of a patient with pulmonary M. malmoense infection and concomitant lung squamous cell carcinoma.