LAUSR

Abstract Rationale: Mycobacterium peregrinum is a member of the group of rapidly growing nontuberculous mycobacteria. It mainly causes surgical site and catheter-related infections, while pulmonary infection is rare. We herein present a case of pulmonary infection caused by M peregrinum. Patient concerns: A 62-year-old woman visited our hospital with dyspnea and was admitted for the treatment of pneumonia in July 2018. Diagnosis: Chest computed tomography showed patchy opacities and consolidation in the bilateral lungs and a cavity in the right upper lobe, which persisted after the treatment of bacterial pneumonia 5 years ago. She was administered ceftriaxone and azithromycin. Consolidation in the bilateral lungs improved, whereas the cavity in the right upper lobe remained and the consolidation surrounding it gradually spread. On admission, the sputum acid-fast bacillus culture was positive, and M peregrinum was identified twice by mass spectrometry. The cavity and consolidation surrounding it were diagnosed as pulmonary mycobacteriosis caused by M peregrinum. Interventions: Although we recommended treatment for mycobacteriosis, the patient refused it. Outcomes: The patient is regularly followed up; however, the cavity wall is thickening and shadows have become mildly enhanced over the course of 3 years. Lessons: We herein present a rare case of pulmonary mycobacteriosis caused by M peregrinum and discuss the literature. Since limited information is currently available on pulmonary mycobacteriosis caused by M peregrinum, the accumulation of further case reports and the clarification of its clinical features are needed.