Differential Diagnosis for Recurrent Bacterial Infections in a 13-month-old Girl
- Single most likely diagnosis:
- Chronic Granulomatous Disease (CGD) - specifically due to a deficiency in the NADPH oxidase system, but more precisely, the description points towards a problem in the production of HOCI, which is related to Myeloperoxidase (MPO) deficiency. However, given the specifics about the production of reactive oxygen species (ROS) being normal except for HOCI, the focus shifts towards an issue in the downstream process of ROS utilization, not the generation of superoxides. Thus, Myeloperoxidase deficiency becomes a strong candidate because MPO is crucial for the conversion of H2O2 into HOCI within neutrophils.
- Other Likely diagnoses:
- Leukocyte Adhesion Deficiency (LAD): Although the production of ROS is normal, issues with adhesion and migration of leukocytes could lead to recurrent infections. However, this doesn't directly explain the decreased production of HOCI.
- Chediak-Higashi Syndrome: Characterized by impaired neutrophil function, but the primary issue is with granule formation and degranulation, not directly with ROS production or HOCI generation.
- Do Not Miss:
- Severe Congenital Neutropenia: Conditions like Kostmann syndrome could lead to severe recurrent infections due to a lack of neutrophils, regardless of their function. Although the question focuses on the function of neutrophils, a severe lack of them could present similarly.
- HIV Infection: Immunodeficiency due to HIV could lead to recurrent infections, but this would not specifically result in the pattern of normal ROS production with decreased HOCI.
- Rare diagnoses:
- Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency: While more commonly associated with hemolytic anemia, severe deficiency could potentially impact NADPH production, affecting oxidative burst. However, this would more likely affect the production of superoxides rather than specifically HOCI.
- Other specific immunodeficiencies: Such as deficiencies in specific cytokines or their receptors, which could lead to impaired neutrophil function or recruitment, but these would not typically present with the specific pattern of normal superoxide production and decreased HOCI production.