Pathological humerus fracture due to anti-interferon-gamma autoantibodies: A case report

BACKGROUND: Various etiologies contribute to pathological fractures, including bone infections. Recently, non-tuberculosis Mycobacterium-related bone infections among patients with anti-interferon-gamma autoantibody-induced adult-onset immunodeficiency has raised concerns in Southeast Asia, with the common presentations including osteomyelitis. However, it also rarely manifests as traumatic fractures, as reported in this case. CASE SUMMARY: A diabetic female fractured her humerus after a traumatic accident and received fixation surgery. Abnormal necrotic bone tissue and abscess formation were noted, and she was diagnosed with a pathological fracture due to non-tuberculosis Mycobacterium infection. Multiple bone involvement was also revealed in a bone scan. Anti-interferon-gamma autoantibodies were then checked due to an unexplained immunocompromised status and found to be positive. Her humerus fracture and multiple bone infections healed after steroid and anti-non-tuberculosis Mycobacterium medication treatment following fixation surgery. CONCLUSION: Comprehensive preoperative evaluations may help identify pathological fractures and guide the treatment course.