Differential Diagnosis for a 15-year-old boy with Chronic Granulomatous Disease
- Single most likely diagnosis:
- Bacterial pneumonia: This is the most likely diagnosis given the patient's history of chronic granulomatous disease (CGD), which predisposes him to recurrent infections, particularly those caused by catalase-positive bacteria. The presence of a new infiltrate in the right lower lobe on the CT scan, along with symptoms of fatigue, anorexia, cough, and low-grade fever, supports this diagnosis. The increased leukocytes and erythrocyte sedimentation rate also indicate an infectious process.
- Other Likely diagnoses:
- Fungal pneumonia: Given the patient's immunocompromised state due to CGD and the fact that he is on itraconazole prophylaxis, fungal infections are a significant concern. Fungal pneumonia could present similarly to bacterial pneumonia and is a common complication in patients with CGD.
- Aspergillosis: This is another fungal infection that could affect the lungs and is particularly concerning in immunocompromised patients. The patient's symptoms and the new infiltrate on the CT scan could be consistent with aspergillosis.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed):
- Sepsis: Although the patient currently has a low-grade fever and localized symptoms, the potential for any infection to rapidly progress to sepsis in an immunocompromised individual is high. Sepsis is a life-threatening condition that requires immediate recognition and treatment.
- Invasive aspergillosis with dissemination: While aspergillosis is mentioned as an other likely diagnosis, its potential to disseminate and cause severe, life-threatening disease warrants its inclusion here as well. Disseminated aspergillosis can affect multiple organs and has a high mortality rate if not promptly treated.
- Rare diagnoses:
- Nocardiosis: This is a rare bacterial infection caused by Nocardia species, which can affect the lungs and is more common in immunocompromised individuals. While less likely, it could present with similar symptoms and should be considered if more common causes are ruled out.
- Actinomycosis: Another rare infection that could affect the lungs, actinomycosis is caused by Actinomyces species. It is less common but could be considered in the differential diagnosis of a patient with CGD who does not respond to typical antibiotic treatments.