Chronic Mycobacterium avium skin and soft tissue infection complicated with scalp osteomyelitis possibly secondary to anti-interferon-γ autoantibody formation

BACKGROUND: Nontuberculous mycobacterial (NTM) disease is commonly an opportunistic infection frequently found in immunocompromised individuals, but sometimes can also be found in the immunocompetent hosts, especially in East Asians. The NTM separation rate in China is increasing, which reminds us to focus on NTM infections in immunocompromised populations. CASE PRESENTATION: A 43-year-old woman with a recurrent fever for more than 8-month and a right forehead surgical wounds unhealed for more than 6-month was admitted to our hospital on February 22, 2018. On arrival, several elliptic ulcers were obvious on the right forehead with pus and fibrin exudation, and the skin around the lesions was tender, reddish, no sense of fluctuation. The result of HIV serology test was negative. CD4+ T cell count was normal and tuberculosis antibody was negative. CT of the chest and head showed bone destruction. Skin biopsy on the right forehead was performed on March 13, 2018, and pathological examination of the excisional biopsy specimen found inflammatory granuloma and suppurative inflammatory changes. Broad-spectrum antibiotics were treated but the effect seemed discontent. Then debridement and skin grafting were performed on the right frontal ulcer under general anesthesia on April 3, 2018. The skin tissue culture that resected on March 13, 2018 found Nontuberculous mycobacteria grown after 78 days, so clarithromycin, ethambutol, protionamide, and amoxicillin clavulanate potassium were prescribed for anti-nontuberculous mycobacteria treatment beginning on May 31, 2018. In reviewing the case, Mycobacterium avium (M. avium) was identified in the skin tissue resected on April 3, 2018 by polymerase chain reaction (PCR) and the serum test of anti-interferon-γ autoantibodies was positive. CONCLUSIONS: This is a case report of “Mycobacterium avium SSTI (skin and soft tissue infection) and OM (osteomyelitis) with possible secondary immunodeficiency syndrome induced by anti-interferon-γ autoantibody”.