Mycobacterium abscessus subspecies massiliense infection with anti-interferon-gamma autoantibodies

Background: In recent years, reports of disseminated nontuberculous mycobacterial (NTM) infections in adults with anti-interferon-gamma (IFN-γ) autoantibodies have increased, particularly in Southeast Asia. The absence of previous immunodeficiency and nonspecific initial symptoms in patients are likely to cause a diagnostic delay. Clinical symptoms, imaging findings, and culture of organ specimens are included in the diagnostic criteria; however, the cultures are not always positive. Granuloma formation is a characteristic pathology of NTM infections, assisting in the diagnosis, which is not observed in the presence of immunodeficiency. Case Report: A 69-year-old Japanese woman with no history of immunodeficiency presented with a pulmonary nodule, neutrophilic dermatosis, and pyogenic lymphadenitis. Bronchoscopy, transbronchial aspiration cytology, endobronchial ultrasound-guided transbronchial needle aspiration, computed tomography-guided lung biopsy, thoracoscopic lymph node biopsy, right subclavian lymph node biopsy, skin biopsy, and blood cultures were performed. Results: While the cultures were negative, a pathological examination revealed inflammatory cell infiltrates, mainly composed of macrophages. Mycobacterium abscessus subsp. massiliense was recovered in an open biopsy of the left inguinal lymph node. Further, QuantiFERON®TB Gold Plus, a commercialized IFN-γ release assay, was inconclusive, whereas anti-IFN-γ autoantibodies were positive. Notably, eight months after symptom onset, the patient was diagnosed with disseminated M. abscessus subsp. massiliense infection associated with adult-onset immunodeficiency due to the presence of anti-IFN-γ autoantibodies. Conclusion: Obtaining this definitive diagnosis was challenging owing to the delayed identification of anti-IFN-γ autoantibodies, a lack of positive cultures, and an absence of granuloma formation. Thus, for early diagnosis, screening for anti-IFN-γ autoantibodies using QuantiFERON®TB Gold Plus, repeated culture examinations, and pathological studies are recommended