Differential Diagnosis for Recurrent Infections in an 8-year-old Boy
Single most likely diagnosis
- C) Defect of intracellular killing: This is the most likely cause given the history of recurrent skin infections, lymphadenitis, and osteomyelitis due to Staphylococcus aureus. Defects in intracellular killing, such as chronic granulomatous disease (CGD), lead to an inability to effectively kill certain bacteria and fungi, resulting in recurrent infections, particularly with catalase-positive organisms like S. aureus.
Other Likely diagnoses
- D) Immunoglobulin deficiency: While less likely than a defect in intracellular killing given the specific pathogens involved, immunoglobulin deficiencies (like IgA deficiency or common variable immunodeficiency) can lead to recurrent infections, including pneumonia and skin infections.
- B) Complement deficiency: Complement deficiencies can lead to increased susceptibility to infections, particularly those caused by Neisseria species. However, the infections described don't strongly point towards a complement deficiency as the primary issue.
Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- E) Impaired splenic function: Although the clinical presentation doesn't strongly suggest impaired splenic function (e.g., asplenia or hyposplenism), it's crucial not to miss this diagnosis due to the risk of severe, life-threatening infections with encapsulated organisms. The history of pneumonia at young ages could be a hint, but the other infections described are less typical for this condition.
- A) Chronic leukopenia: Chronic leukopenia could lead to recurrent infections, but the specific pattern of infections and the presence of a warm, tender erythematous mass in the groin (suggestive of an abscess or infected lymph node) makes this less likely compared to a defect in intracellular killing.
Rare diagnoses
- Other rare immunodeficiencies, such as hyper-IgE syndrome (Job syndrome), could also present with recurrent skin infections and pneumonias, but the specific combination of infections and family history (maternal uncle dying of pneumonia in infancy) makes C) Defect of intracellular killing more likely, particularly considering X-linked CGD.