An 18-month-old boy is brought to the emergency department for evaluation of
shortness of breath and cough. Past medical history includes two episodes of
pneumonia,
oral thrush, chronic diarrhea and recurrent
otitis media. His
vaccinations are not up to date due to frequent illnesses. Family history is non-contributory. The patient is at the 2nd percentile for height and weight. Temperature is 38.7 C (101.7 F),
pulse is 151/min, respirations are 36/min and
blood pressure is 70/40 mmHg. Physical examination demonstrates white patches in the
oral cavity and diffuse rales of the lungs bilaterally. Laboratory results are demonstrated below.
| Complete blood count |
| Leukocyte count | 8,100 /mm3 |
| Platelet count | 300,000/mm3 |
| Lymphocytes | 5% |
| CD 19+ | low |
| CD 3+ | absent |
| Immunoglobulins |
| IgG | 220mg/dL |
| IgA | 40 mg/dL |
| IgM | 15 mg/dL |
Chest X-ray demonstrates bilateral diffuse interstitial infiltrates. Which of the following is the most likely diagnosis?
