Aids in Children 1

Question

Vignette:

A 5-year-old boy is brought to the doctor by his mother who is concerned about his recurring infections. He has had 4 episodes of pneumonia in the past year, and his mother reports that he always seems to have a cold or a respiratory infection. Physical examination shows oral thrush. Laboratory tests show a low CD4+ T-cell count. A dihydrorhodamine (DHR) test is performed and it shows normal oxidative burst. The physician suspects a defect in the immune system. Which of the following is the most likely diagnosis?

Choices

A. Chronic granulomatous disease

B. Severe combined immunodeficiency (SCID)

C. Bruton's agammaglobulinemia

D. Wiskott-Aldrich Syndrome

E. DiGeorge Syndrome

Answer

B. Severe combined immunodeficiency (SCID)

Explanation

Severe combined immunodeficiency (SCID) is a primary immunodeficiency disorder characterized by a severe defect in both the T- & B-lymphocyte systems. This results in the child's inability to fight off infections, leading to recurrent infections as seen in this patient. The presence of oral thrush indicates a candidal infection, which is common in SCID due to the loss of T-cell-mediated immunity. The low CD4+ T-cell count is also indicative of SCID.

The normal DHR test result helps rule out chronic granulomatous disease, which would show an abnormal (decreased) oxidative burst. Bruton's agammaglobulinemia predominantly affects B cells, leading to recurrent bacterial, but not fungal, infections. Wiskott-Aldrich Syndrome presents with eczema, thrombocytopenia, and recurrent infections, but often with normal or elevated IgM levels. DiGeorge Syndrome is characterized by the absence or underdevelopment of the thymus and parathyroid glands, leading to low calcium levels and issues related to T cell immunity, but it also commonly presents with congenital heart disease and specific facial features, which are not mentioned in this vignette.