Background

Infections with atypical mycobacteria are rare and sometimes difficult to correctly diagnose. In many cases underlying diseases such immune deficiency can promote these infections.
Case presentation

A 43-year-old male of Southeast Asian origin presented to our tertiary care hospital with persistent cervical lymphadenopathy non-responsive to antibiotics. Imaging suggested malignancy, but a biopsy did not confirm this suspicion. PCR diagnostics identified Mycobacterium genavense and further immunological testing revealed an acquired adult-onset immunodeficiency due to neutralizing anti-IFN-γ autoantibodies (nAIGA), explaining both the current infection and previous pleural empyema. The patient responded well to triple antimycobacterial therapy, with no recurrence or novel infection after almost two years.
Conclusions

Our case highlights the importance of considering underlying immunodeficiencies and the patient’s geographic origin in the diagnosis of rare infections.