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Difficulty: MediumImmunologic and Inflammatory Processes

Match each pediatric patient's clinical presentation with the underlying primary immunologic defect.

  • 4-year-old boy with recurrent severe periodontitis, mucosal infections without pus formation, and a history of delayed umbilical cord separationDefective tight adhesion and transmigration of neutrophils
  • 5-year-old boy with a history of recurrent Aspergillus pneumonia, suppurative lymphadenitis, and a negative (abnormal) dihydrorhodamine 123 testImpaired phagocyte respiratory burst
  • 6-year-old girl with recurrent pyogenic infections, partial oculocutaneous albinism, and progressive peripheral neuropathyDefective microtubule polymerization and lysosomal trafficking
  • 6-month-old boy presenting with failure to thrive, persistent oral candidiasis, and absent thymic shadow on chest radiographyImpaired T-cell proliferation due to defective cytokine signaling

Answer

The patient with delayed cord separation matches with defective tight adhesion. The patient with Aspergillus and abnormal DHR matches with impaired phagocyte respiratory burst. The patient with partial albinism matches with defective microtubule polymerization. The patient with persistent candidiasis and absent thymus matches with impaired T-cell proliferation.
Each patient's clinical presentation precisely maps to a specific cellular or molecular defect within the innate or adaptive immune system. Identifying unique clinical clues (e.g., albinism, absent pus, absent thymus, specific diagnostic test results) correctly bridges the diagnosis to the underlying pathophysiology.

Step-by-Step Solution

1
Analyze the clinical vignette for the 4-year-old boy.
Identify Leukocyte Adhesion Deficiency (LAD) based on the classic triad of recurrent infections without pus, severe periodontitis, and delayed umbilical cord separation.
This phenotype is driven by the inability of neutrophils to exit the vasculature, pointing to defective adhesion and transmigration.
2
Evaluate the clinical vignette for the 5-year-old boy.
Identify Chronic Granulomatous Disease (CGD) indicated by infections with catalase-positive organisms (Aspergillus) and an abnormal DHR test.
The DHR test evaluates the phagocyte's ability to generate reactive oxygen species, which is impaired due to NADPH oxidase deficiency.
3
Assess the clinical vignette for the 6-year-old girl.
Identify Chediak-Higashi syndrome based on the combination of immunodeficiency, partial albinism, and neurological symptoms.
This specific symptom triad is the result of defective lysosomal trafficking and microtubule dysfunction (LYST gene mutation).
4
Review the clinical vignette for the 6-month-old boy.
Identify Severe Combined Immunodeficiency (SCID) due to early-onset opportunistic infections (thrush), failure to thrive, and absent thymic shadow.
Profound early-onset defects in cellular and humoral immunity are typically caused by profound T-cell deficiencies, commonly due to cytokine receptor defects like the IL-2 receptor gamma chain.

Key Concept

Clinical and pathophysiologic correlations of primary immunodeficiencies
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Topics

Immunologic and Inflammatory Processes

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