Pediatric Examination and Board Review (114 page)

Hay WW Jr, Hayward AR, Levin MJ, et al.
Current Pediatric
Diagnosis and Treatment
. New York, NY: McGraw-Hill; 2008.

Lasley MV, Shapiro GG. Testing for allergy.
Pediatr Rev.
2000;21:39-43.

Weiss ME, Adikinson NF. Immediate hypersensitivity reactions to penicillin and related antibiotics.
Clin Allergy.
1988;18: 515-540.

Winberry SL, Liberman PL. Anaphylaxis.
Immunol Allergy Clin North Am.
1995;15:477.

CASE 70: A 3-MONTH-OLD WITH POOR WEIGHT GAIN, RECURRENT INFECTION, AND DIARRHEA

A 3-month-old male infant has been brought to your clinic for evaluation of diarrhea. Mom reports that he has had diarrhea “since birth” and has seen at least 3 doctors over the course of 3 months. Each doctor switched the patient’s formula, initially from breast milk through multiple types of standard cow’s milk and soy formula followed by elemental formula, all with no relief. The stools are described as nonbloody, runny, and occur about 7 times per day. Mom denies any emesis or difficulty with feeds (no cyanosis, diaphoresis, arching, or discomfort). On review of systems she does note that he has had several episodes of cough and respiratory distress requiring antibiotics, as well as recurrent thrush. The birth history is unremarkable except for a lack of prenatal care. The birthweight was 3.6 kg, length 50 cm, head circumference (HC) 35.5 cm. Both mom and infant were discharged on postnatal day 2.

The physical examination is noteworthy for a small child who weighs 4.0 kg. The length is 55 cm and the HC is 39.5 cm. He is alert and active. His oral cavity has white plaques but no vesicles or other lesions. The cardiac examination has a regular rate and rhythm, no murmurs, and good peripheral pulses. The chest examination reveals coarse breath sounds with intermittent crackles at left base. The abdominal examination reveals a liver edge approximately 2 cm below the costal margin, with a spleen edge palpable 1.5 cm below the costal margin. There is no lymphadenopathy. Otherwise the physical examination is unremarkable.

SELECT THE ONE BEST ANSWER

1.
What is the most likely cause of the patient’s symptoms?

(A) B-cell deficiency

(B) T-cell deficiency

(C) phagocyte deficiency

(D) abnormal mucociliary clearance

(E) lactase deficiency

2.
Which of the following would not be included in the initial workup of this patient?

(A) Western blot for HIV

(B) CBC with differential

(C) quantitative immunoglobulins

(D) lymphocyte subsets

(E) stool culture

3.
The results of the initial testing reveal the following:

HIV enzyme-linked immunosorbent assay

(ELISA): nonreactive

Absolute lymphocyte count: 2200/mm
³

CD3
⁺
T cells: 15%

Immunoglobulins: Normal

HIV DNA PCR: nonreactive

Which of the following is the most likely diagnosis with this information?

(A) DiGeorge syndrome

(B) Wiskott-Aldrich syndrome

(C) congenital HIV

(D) severe combined immunodeficiency (SCID)

(E) chronic mucocutaneous candidiasis

4.
Which of the following tests can confirm the definitive diagnosis of SCID?

(A) search for a JAK3 mutation

(B) search for a RAG1 or RAG2 mutation

(C) search for a IL-7Rα mutation

(D) less than 2% activity in ADA control

(E) all of the above

5.
Which of the following is the best treatment for the above patient?

(A) routine IVIG transfusions

(B) HLA-identical stem cell transplantation

(C) haploidentical donor stem cell transplantation

(D) gene therapy

(E) none of the above

6.
Which of the following lymphocyte subset markers reflect B cells?

(A) CD3

(B) CD4

(C) CD14

(D) CD16

(E) CD20

7.
Which of the following is the most common immunodeficiency?

(A) hyper IgM syndrome

(B) CF

(C) IgA deficiency

(D) common variable immunodeficiency

(E) cyclic neutropenia

8.
A defect in which of the following would most likely account for a patient with recurrent staphylococcal infections, partial albinism, and long-term risk of hemophagocytosis?

(A) leukocyte adhesion

(B) lysosomal transport

(C) phagocyte oxidase

(D) elastase

(E) none of the above

9.
A 6-year-old boy comes to the emergency department with fever, cough, and chest pain. While there he is noted to have hemoptysis and is saturating 87% on RA. A chest radiograph reveals bilateral lower lobe infiltrates. He is admitted and begun on ceftriaxone and vancomycin. With no improvement after 36 hours and an unchanged chest radiograph, bronchoscopy reveals large mucus plugs and positive culture for
Aspergillus nidulans
. Which of the following immunodeficiencies would most likely underlie this illness?

(A) Wiskott-Aldrich

(B) leukocyte adhesion deficiency (LAD) type 1

(C) common variable immunodeficiency

(D) chronic granulomatous disease

(E) Kostmann syndrome

10.
Which of the following bacterial etiologies commonly cause infections among patients with chronic granulomatous disease?

(A)
S pneumoniae

(B)
Klebsiella
spp.

(C)
S aureus

(D) A and C

(E) B and C

11.
The genetic defect in chronic granulomatous disease results in abnormal function of what chemical reactant?

(A) leukocyte integrins

(B) myeloperoxidase

(C) NADPH-oxidase

(D) adenosine deaminase

(E) LYST protein

12.
Which of the following is suggestive of chronic granulomatous disease (CGD)?

(A) positive Rebuck skin window

(B) abnormal neutrophil flow cytometry

(C) abnormal nitroblue tetrazolium test

(D) abnormal giant granules in neutrophils

(E) none of the above

13.
Treatment strategies for chronic granulomatous disease include all except

(A) trimethoprim-sulfamethoxazole prophylaxis

(B) interferon (IFN)-gamma

(C) aggressive bacterial species-specific antibiotic therapy

(D) gene therapy

(E) A and C

14.
Which of the following is true regarding cutaneous delayed-type hypersensitivity testing?

(A) it is reliable after the age of 6 months

(B) it employs tetanus toxoid, rubella antigen, and
Candida
antigens

(C) it is a definitive diagnostic tool

(D) a positive test is considered more than 5 mm induration in all cases

(E) a positive test reflects abnormal cellular immunity

15.
Which of the following is not true regarding humoral immune deficiencies?

(A) presentation is usually after 6 months of life

(B) sinopulmonary infections are common

(C)
H influenzae
is a common pathogen

(D) bone marrow transplant is the mainstay of therapy

(E) hypogammaglobulinemia is a hallmark

16.
Which of the following viruses is not inactivated during IVIG preparation?

(A) hepatitis A

(B) hepatitis B

(C) hepatitis C

(D) HIV

(E) herpes viruses

17.
How often should IVIG be given for humoral immunodeficiencies?

(A) every 1-2 weeks

(B) every 3-4 weeks

(C) every 1-2 months

(D) every 3-4 months

(E) weekly

18.
Patients with which humoral immune disorder cannot receive standard IVIG?

(A) common variable immunodeficiency

(B) Bruton gamma-globulinemia

(C) selective IgA deficiency

(D) IgG subclass deficiency

(E) none of the above

ANSWERS

1.
(B)
The most likely etiology for this patient’s symptoms is a defect in T-cell function and/or number. Isolated B-cell deficiencies do not normally present until after 6 months when maternal antibody wanes. Phagocyte dysfunction syndromes do not present with recurrent pulmonary infection or failure to thrive (FTT). A combined immunodeficiency could present like this, but at this age, the T-cell deficiency would be the primary driver of clinical symptoms. Although lactase deficiency could explain the diarrhea, it would not explain the recurrent infections. Abnormal mucociliary clearance, as occurs in CF, could present with diarrhea, FTT, and respiratory symptoms but is less likely to cause thrush; there is an associated lack of lymphoid tissue.

2.
(A)
Initial evaluation for this patient should be directed at uncovering an underlying immune deficiency. Although HIV should be considered, the Western blot should not be used as a screening test; a DNA PCR would be the appropriate initial laboratory evaluation in this age group. Infant or maternal HIV ELISA testing may also provide useful information but neither would be diagnostic in the infant. A CBC with differential, quantitative immunoglobulins and lymphocyte subsets would all be useful. A stool culture would screen for bacterial pathogens causing the diarrhea.