Mycobacterium paragordonae pulmonary disease with rapidly growing solitary lesions: a case report and literature review

INTRODUCTION: Mycobacterium paragordonae (MPG) is a novel and uncommon nontuberculous mycobacterium (NTM). We describe a case of MPG pulmonary disease (MPGPD) with a single, rapidly growing, pulmonary mass, which has rarely been reported. CASE REPORT: A chest CT scan of a 66-year-old woman revealed a rapidly growing solitary mass-like lesion in the upper lobe of the right lung, which was not seen in the previous chest CT scan six months ago. H&E-stained section of the CT-guided percutaneous lung tissue biopsy specimen showed chronic inflammatory changes with epithelioid granulomas. Metagenomic next-generation sequencing (mNGS) of lung tissue biopsy specimen identified MPG with a sequence number of 1617 and a confidence level of 99%. Because the subsequent MPG droplet digital PCR (MPG-ddPCR) test of the lung tissue biopsy was positive, she was eventually diagnosed with MPGPD. She was administered a quadruple oral regimen comprising clarithromycin, levofloxacin, rifampicin, and ethambutol according to the ATS/IDSA protocol for Mycobacterium gordonae (MG) infection. The chest CT scans showed a significant reduction in the lesion one month after the treatment and almost complete resolution four months later. CONCLUSIONS: MPGPD is a rare NTM infection. The imaging manifestations of MPGPD are diverse and may even show rapid development. mNGS of tissue biopsy can enable prompt diagnosis of MPG infection and is a good alternative to routine NTM microbial testing. The ATS/IDSA protocol for MG infection is an effective treatment for MPG infection.