Case of pulmonary Mycobacterium mageritense infection: the difficulty of differential diagnosis of granulomatous lung diseases

Abstract

A 36 year-old female was pointed out of pulmonary abnormal shadows in the annual chest survey. Chest radiograph and computed tomography (CT) disclosed bilateral diffuse infiltrative shadows and tree-in-bud appearance in the right upper lung field and the left lingula. A sputum smear for acid-fast bacilli was negative. Histopathologically, the transbronchial lung biopsy specimen revealed non-caseous epithelioid granulomas with numerous giant cells. Acid-fast bacilli were cultured from her sputum, however, nontuberculous mycobacteria was not detected by DNA-DNA hybridization method. Mycobacterium mageritense was identified by 16S ribosomal RNA sequencing with 100% matching. The isolated colony of M. mageritense was resistant to nine anti-tuberculous drugs. Follow-up chest CT scan showed a gradual decrease of infiltrative shadows without therapy. To the best of our knowledge, M. mageritense infections are rare, and this is the first case report of pulmonary infection in the literature. We conclude that the pulmonary infection of M. mageritense is one of causes of granuloma formation, and in some case it is difficult to differentiate clinically from sarcoidosis.