Pediatric Immunology

Question 1

Chronic granulomatous disease

Question 2

C2 deficiency

Question 3

SCID

Answer 3

• No B or T cells
• Often some degree of thymic aplasia on imaging
• Recurrent cutaneous, gastrointestinal, and pulmonary infections
• Often opportunistic organisms like CMV and PCP
• Death typically occurs in first 2 years of life unless bone marrow transplant is performed

Question 4

Common forms of secondary immunodeficiency

Answer 4

• HIV
• Diabetes
• Malnutrition
• Liver disease
• Autoimmune disease (scleroderma)
• Stress

Question 5

Verifying HIV infection in a child

Answer 5

• Child must be older than 18 months for antibody testing to be effective
  
  • Since maternal antibody transfer will confound results
  • If younger than 18 months, HIV DNA PCR is used. Two positive tests on separate occasions are necessary to confirm the diagnosis.
  • If older than 18 months, the typical HIV ELISA and confirmatory WB are utilized

Question 6

Treatment of the neonate born to an HIV+ mother

Answer 6

• Typical pregnancy and delivery precautions (aggressive prenatal ART, intrapartum ziduvodine, C section if VL > 1000, etc)
• Test neonate at birth and select occasions up to 6 months with HIV DNA PCR
• Start infant on 6 week course of oral ziduvodine within the first three hours of life
• Begin PCP prophylaxis at 6 weeks with TMP-SMX IF HIV +
• Begin HAART at earliest possible opportunity IF HIV +

Question 7

Failure of the umbilical cord remnant to regress after 6 weeks, despite being kept dry, is an indication of. . .

Answer 7

. . . neutrophil dysfunction

Question 8

Poorly-healing wounds without pus in a newborn are suggestive of. . .

Answer 8

. . . leukocyte adhesion deficiency

Especially if in the context of a retained umbilical stump and neutrophilia

Question 9

DiGeorge syndrome

Answer 9

Diagnosis is clinical. CBC shows low absolute lymphocytes.

Treat with TMP-SMX ppx against PCP, IVIG as bridge to thymic transplant

Question 10

GI complications of HSP

Answer 10

• Hemorrhage
• Obstruction
• Intussusception
• Since these complications are so severe, abdominal pain in a patient with suspected HSP requires close evaluation

Question 11

Kawasaki disease

Answer 11

• Form of generalized vasculitis thought to be infectious or induced by infection
• Occurs most commonly in those < 5 years of age, and is most severe in those < 1 year of age
• Symptoms include: High spiking fever for >5 days, bilateral nonpurulent conjunctavitis, oropharyngeal mucosal changes (injection, strawberry tongue, etc), polymorphous rash that is primarily truncal, edema or erythema of hands and feet, acute nonpurulent cervical lymphadenopathy
  
  • ​Limbus-sparing conjunctival injection is pathognomonic
• CAD and coronary aneurysm development during this time are important complications
  
  • Most deaths in KD result from CAD or coronary aneurysm rupture
• Diagnosis: Above symptoms + elevated ESR and CRP. Normocytic anemia and leukocytosis are common. Thrombocytosis appears by day 10 of fevers.
• Treatment: Immediately start high-dose aspirin and IVIG. Aspirin is reduced to anti-thrombotic dose when ESR normalizes.Pediatric cardiologist should be consulted for cardiac workup, usually involving echocardiogram.

Question 12

Risk factors for aneurysm development in Kawasaki disease

Answer 12

• Male gender
• Prolonged fever
• <1 year of age
• Higher baseline neutrophil and band counts
• Lower hemoglobin
• Platelet count < 350,000 or >1,000,000

Question 13

Vaccinations and IVIG

Answer 13

Live vaccines are delayed for 11 months following high-dose IVIG administration, as they interfere with the immune response

Question 14

Children with Kawasaki disease that are at the highest risk of CAD are those with. . .

Answer 14

. . . atypical Kawasaki disease

Which lacks some of the diagnostic criteria

Question 15

Bruton agammaglobulinemia

Answer 15

• X-linked recessive (aka X-linked agammaglubulinemia)
• Impaired B cell maturation, often no circulating B cells
• Results in recurrent sinopulmonary infections starting after 6 months of age (when mom’s IgG is wearing off)
• Diagnose w/ flow cytometry showing absence of B cells and quantitative immunoglobulins
  
  • Can confirm with BTK genotyping
• Treat w/ monthly IVIG infusion and antibiotics as needed

Question 16

Forms of allergic conjunctavitis

Answer 16

• Vernal conjunctavitis: IgE-mediated, bilateral, season, and self-limiting. Severe itchiness and reflex lacrimation. Involves “giant cobblestone papillae” on the upper tarsal conjunctiva
• Giant papillary conjunctavitis: Presents with foreign body sensation, itching, and mild mucoid discharge in patients who wear contact lenses or ocular protheses. Exam shows “giant” papillae, > 1 mm.

Question 17

Phlyctenural conjunctavitis

Answer 17

• Manifestation of type IV hypersensitivity
• Reaction to endogenous microbial proteins (Staphylococcal, tubercular)
• Itching and mild watery eye discharge
• Exam shows a pinkish-white nodule surrounded by hyperemia on the bulbar conjunctiva

Question 18

Testing for ITP

Answer 18

There ain’t any good ones. Sucks huh.

Question 19

Angioedema of C1 esterase deficiency

Answer 19

• • Treatment: Secure the airway, give FFP (which contains C1 esterase)

Question 20

Buzz words for pediatric allergy

Answer 20

• Allergic shiners (shiny areas under eyes)
• Allergic salute (crease in nose from wiping)
• Pale, boggy nose mucosa
• Nasal polyps or cobblestoning (from postnasal drip)

Question 21

The “correct answer” for treating allergic rhinitis or conjunctavitis on the test

Answer 21

Intranasal steroids

Lots of other things work and are used, but on the test they want you to pick steroids

Question 22

Food allergies that are more benign and often go away vs those that are likely to be anaphylactic and remain throughout life

Answer 22

Benign, go away: Wheat, milk, soy, egg

Anaphylactic, stay: Nuts, shellfish

Question 23

How can you tell if a child is having a food sensitivity or food-induced eczema?

Answer 23

Elimination diet and serial reintroduction

Question 24

Milk protein allergy

Answer 24

• In response to soy formula
• Usually presents as failure to thrive, N/V/D, bloody bowel movement
• Diagnosis is clinical
• Treatment is to change formulas (use breast milk or hydrolyzed formula)

Question 25

Tips that a patient might have an immunodeficiency

Answer 25

• Recurrent infections
• Severe presentations of typically benign pathogens
• Unusual pathogens

Question 26

Typical presentation of CVID

Answer 26

Think of CVID like a more mild Bruton’s agammaglobulinemia.

Recurrent infections, but less severe, and typically in a teen who would not have lived this long without treatment if they had Bruton’s

CBC will be normal, quantitative Ig will show a decrease in two of IgG, IgA, IgM, but not all three.

Question 27

IgA deficiency

Answer 27

• Two presentations:
  
  1. Recurrent mucosal infections: sinopulmonary, GI bugs
  2. Anaphylaxis during blood transfusion
• QIG show decreased IgA, but increased IgG and IgM

Question 28

Hyper IgM syndrome

Answer 28

• No mature B cells – deficiency in CD40-CD40L activity
• Nonspecific immune deficiency
• CBC normal, QIG shows high IgM, no IgG, no IgA

Question 29

Individuals with DiGeorge syndrome at most risk for infection with ___

Answer 29

Individuals with DiGeorge syndrome at most risk for infection with fungi and PCP

Question 30

Embryology of DiGeorge syndrome

Answer 30

Ultimately it is caused by absence of the 3rd pharyngeal pouch, which normally develops into the parathyroid and thymus

Question 31

Wiskott-Aldrich diagnosis and treatment

Answer 31

• X-linked, history of atopy
• CBC shows low WBC, low platelets
• QIG shows low IgG and IgM, but high IgE and IgA
• Treatment: Bone marrow transplant is only cure

Question 32

Mutation that causes SCID

Answer 32

Adenosine deaminase deficiency

Question 33

Treatment for SCID

Answer 33

• Isolation (bubble baby)
• TMP-SMX as PCP ppx
• BONE MARROW TRANSPLANT

Question 34

If patient presents with recurrent Staph abscesses, you should think of ___ and test with ___.

Answer 34

If patient presents with recurrent Staph abscesses, you should think of CGD and test with nitro-blue tetrazolium test.

Question 35

Treatment for CGD

Answer 35

Bone marrow transplant

Question 36

Chediak-Higashi syndrome

Answer 36

• Autosomal recessive
• Albinism (sometimes)
• Neuropathy (sometimes)
• Neutropenia
• Giant granules in neutrophils

Question 37

Two important complement disorders

Answer 37

• C1 esterase deficiency: Recurrent, unprovoked angioedema. Treat w/ fresh frozen plasma.
• Late complement deficiency / C5-9 deficiency: Neisseria infections.