Question 141: Given the immunologic abnormalities of normal serum IgG, normal serum IgA, normal serum IgM, decreased T-cell function, and decreased parathyroid function, which clinical presentation is most likely?
- A. A 1-year-old boy with severe eczema, recurrent middle-ear infections, lymphopenia, and thrombocytopenia
- B. A 9-year-old boy with an eczema-like rash and recurrent severe staphylococcal infections
- C. A 5-year-old boy who, after 3 months of age, developed recurrent otitis media, pneumonia, diarrhea, and sinusitis, often with simultaneous infections at two or more disparate sites
- D. A distinctive-appearing 8-month-old boy with an interrupted aortic arch, hypocalcemia, and cleft palate (Correct Answer)
Explanation: ***A distinctive-appearing 8-month-old boy with an interrupted aortic arch, hypocalcemia, and cleft palate***
- This presentation is highly suggestive of **DiGeorge syndrome**, characterized by **thymic hypoplasia** (leading to decreased T-cell function) and **parathyroid hypoplasia** (causing hypocalcemia).
- **Cardiac defects** (like an interrupted aortic arch) and **facial anomalies** (including cleft palate) are also classic features of this disorder, which involves a deletion on chromosome 22q11.2.
*A 1-year-old boy with severe eczema, recurrent middle-ear infections, lymphopenia, and thrombocytopenia*
- This clinical picture describes **Wiskott-Aldrich syndrome**, an X-linked disorder characterized by the triad of eczema, thrombocytopenia (with small platelets), and immunodeficiency leading to recurrent infections.
- While it involves immunodeficiency and lymphopenia, it does not typically present with decreased parathyroid function.
*A 9-year-old boy with an eczema-like rash and recurrent severe staphylococcal infections*
- This presentation is characteristic of **hyper-IgE syndrome** (Job's syndrome), an immunodeficiency characterized by extremely elevated IgE levels, recurrent staphylococcal skin infections, and eczema.
- The immunologic abnormalities described in the stem (normal Ig levels, decreased T-cell function, decreased parathyroid function) do not match the key features of hyper-IgE syndrome.
*A 5-year-old boy who, after 3 months of age, developed recurrent otitis media, pneumonia, diarrhea, and sinusitis, often with simultaneous infections at two or more disparate sites*
- This description is consistent with **X-linked agammaglobulinemia (XLA)**, where B-cell maturation is blocked, leading to a profound deficiency of all immunoglobulin classes.
- The stem mentions normal serum IgG, IgA, and IgM, which rules out XLA.
