Disseminated BCGosis in an infant with mendelian susceptibility to mycobacterial diseases: A case report

Rationale: Primary immunodeficiency disorders can be fatal especially in infants. Prompt recognition with a comprehensive medical history, genetic evaluation, and appropriate treatment can be lifesaving in a few subtypes. Patient concerns: A 4-month-old male infant presented with axillary swelling, fever, and ulcerative lesions. Despite care at multiple facilities, symptoms persisted, raising concern for an underlying immunodeficiency. The patient's sibling had similar symptoms and died at six months, suggesting a genetic predisposition. Diagnosis: Mendelian susceptibility to mycobacterial disease, IFNGR2 deficiency. Interventions: The patient was treated with tailored anti-tubercular therapy and azithromycin prophylaxis. Outcomes: Following treatment, the patient’s symptoms have resolved. At 20 months, he is thriving with normal development. Lessons: This case highlights the importance of a thorough medical history and genetic testing in infants with recurrent or unusual infections. Early diagnosis of mendelian susceptibility to mycobacterial disease can lead to effective treatment and better outcomes.