Introduction: Anti-interferon-gamma (anti-IFN-γ) autoantibody increases susceptibility to lower-virulence pathogens and causes immunodeficiency syndrome in HIV-negative patients.
Patient concerns: A 69-year-old Chinese man presented with a 2-month history of pruritic skin lesions on his forearms, trunk, and legs. He was diagnosed with 5 opportunistic infections without conventional immunosuppression-associated factors in past. The most conspicuous characteristics were recurrent pulmonary infection, persistent immunoglobulin E elevation and eosinophilia during the whole disease course.
Diagnosis: Enzyme-linked immunosorbent assay showed anti-IFN-γ autoantibody positive. The final diagnosis for the patient was adult-onset immunodeficiency due to anti-IFN-γ autoantibody, non-tuberculous mycobacterial (NTM) infection and reactive dermatosis.
Interventions: The patient underwent long-term anti-NTM and corticosteroid maintenance treatment.
Outcomes: The patient was followed for 2 years during which opportunistic infection no longer happened, the immunoglobulin E level and eosinophil count reduced, the autoantibody levels remained largely steady and lung lesions absorbed.
Conclusion: Clinicians should be vigilant for NTM infection in patients with anti-IFN-γ autoantibodies, even when culture results are negative. Long-term anti-non-tuberculous mycobacteria and glucocorticoid regimens were effective.