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Microscopic Polyangiitis After Pulmonary Nontuberculous Mycobacterial Disease: A Case Report and Literature Review

Hidenori Takahashi1, Riho Nakagawa1, Mio Toyama-Kousaka1

  • 1Department of Respiratory Medicine Tokyo Shinagawa Hospital Tokyo Japan.

Respirology Case Reports
|May 14, 2026
PubMed

Insights

Nontuberculous mycobacterial pulmonary disease (NTM-PD) can rarely present with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Early recognition and treatment of this rare complication are crucial for managing NTM-PD patients.

Area of Science:

  • Pulmonology
  • Rheumatology
  • Nephrology

Background:

  • Nontuberculous mycobacterial pulmonary disease (NTM-PD) is typically viewed as an infection.
  • Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a rare condition that can mimic infectious exacerbations of NTM-PD.

Purpose of the Study:

  • To highlight the importance of considering ANCA-associated vasculitis in patients with NTM-PD presenting with atypical symptoms.
  • To describe a case of NTM-PD complicated by ANCA-associated vasculitis.

Main Methods:

  • Case report of an 80-year-old Japanese woman with NTM-PD.
  • Clinical presentation, laboratory findings (including MPO-ANCA test), renal biopsy, and nerve conduction studies were analyzed.
  • Treatment response to immunosuppressive therapy (methylprednisolone, prednisolone, rituximab) was evaluated.

Main Results:

  • The patient presented with NTM-PD, bronchiectasis, and Pseudomonas aeruginosa colonization, exhibiting persistent inflammation, hematuria, proteinuria, and casts despite antibiotic treatment.
  • Myeloperoxidase (MPO)-ANCA test was strongly positive (783 U/mL).
  • Treatment with methylprednisolone, prednisolone, and rituximab led to a decrease in MPO-ANCA titre, stable renal function, and improved systemic inflammation, though neuropathy persisted.

Conclusions:

  • ANCA-associated vasculitis is a rare but important complication to consider in patients with NTM-PD experiencing organ-specific manifestations.
  • Prompt diagnosis and immunosuppressive treatment can improve outcomes in NTM-PD patients with concurrent ANCA-associated vasculitis.
Keywords:
bronchiectasiscrescentic glomerulonephritismicroscopic polyangiitismyeloperoxidase‐ANCAnontuberculous mycobacteria

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