Pediatric Immunology Flashcards
Chronic granulomatous disease
C2 deficiency
SCID
- 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
Common forms of secondary immunodeficiency
- HIV
- Diabetes
- Malnutrition
- Liver disease
- Autoimmune disease (scleroderma)
- Stress
Verifying HIV infection in a child
- 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
Treatment of the neonate born to an HIV+ mother
- 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 +
Failure of the umbilical cord remnant to regress after 6 weeks, despite being kept dry, is an indication of. . .
. . . neutrophil dysfunction
Poorly-healing wounds without pus in a newborn are suggestive of. . .
. . . leukocyte adhesion deficiency
Especially if in the context of a retained umbilical stump and neutrophilia
DiGeorge syndrome
Diagnosis is clinical. CBC shows low absolute lymphocytes.
Treat with TMP-SMX ppx against PCP, IVIG as bridge to thymic transplant
GI complications of HSP
- Hemorrhage
- Obstruction
- Intussusception
- Since these complications are so severe, abdominal pain in a patient with suspected HSP requires close evaluation
Kawasaki disease
- 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.
Risk factors for aneurysm development in Kawasaki disease
- Male gender
- Prolonged fever
- <1 year of age
- Higher baseline neutrophil and band counts
- Lower hemoglobin
- Platelet count < 350,000 or >1,000,000
Vaccinations and IVIG
Live vaccines are delayed for 11 months following high-dose IVIG administration, as they interfere with the immune response
Children with Kawasaki disease that are at the highest risk of CAD are those with. . .
. . . atypical Kawasaki disease
Which lacks some of the diagnostic criteria
Bruton agammaglobulinemia
- 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
Forms of allergic conjunctavitis
- 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.
Phlyctenural conjunctavitis
- 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
Testing for ITP
There ain’t any good ones. Sucks huh.
Angioedema of C1 esterase deficiency
- Treatment: Secure the airway, give FFP (which contains C1 esterase)
Buzz words for pediatric allergy
- Allergic shiners (shiny areas under eyes)
- Allergic salute (crease in nose from wiping)
- Pale, boggy nose mucosa
- Nasal polyps or cobblestoning (from postnasal drip)
The “correct answer” for treating allergic rhinitis or conjunctavitis on the test
Intranasal steroids
Lots of other things work and are used, but on the test they want you to pick steroids
Food allergies that are more benign and often go away vs those that are likely to be anaphylactic and remain throughout life
Benign, go away: Wheat, milk, soy, egg
Anaphylactic, stay: Nuts, shellfish
How can you tell if a child is having a food sensitivity or food-induced eczema?
Elimination diet and serial reintroduction
Milk protein allergy
- 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)
Tips that a patient might have an immunodeficiency
- Recurrent infections
- Severe presentations of typically benign pathogens
- Unusual pathogens
Typical presentation of CVID
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.
IgA deficiency
- Two presentations:
- Recurrent mucosal infections: sinopulmonary, GI bugs
- Anaphylaxis during blood transfusion
- QIG show decreased IgA, but increased IgG and IgM
Hyper IgM syndrome
- No mature B cells – deficiency in CD40-CD40L activity
- Nonspecific immune deficiency
- CBC normal, QIG shows high IgM, no IgG, no IgA
Individuals with DiGeorge syndrome at most risk for infection with ___
Individuals with DiGeorge syndrome at most risk for infection with fungi and PCP
Embryology of DiGeorge syndrome
Ultimately it is caused by absence of the 3rd pharyngeal pouch, which normally develops into the parathyroid and thymus
Wiskott-Aldrich diagnosis and treatment
- 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
Mutation that causes SCID
Adenosine deaminase deficiency
Treatment for SCID
- Isolation (bubble baby)
- TMP-SMX as PCP ppx
- BONE MARROW TRANSPLANT
If patient presents with recurrent Staph abscesses, you should think of ___ and test with ___.
If patient presents with recurrent Staph abscesses, you should think of CGD and test with nitro-blue tetrazolium test.
Treatment for CGD
Bone marrow transplant
Chediak-Higashi syndrome
- Autosomal recessive
- Albinism (sometimes)
- Neuropathy (sometimes)
- Neutropenia
- Giant granules in neutrophils
Two important complement disorders
- C1 esterase deficiency: Recurrent, unprovoked angioedema. Treat w/ fresh frozen plasma.
- Late complement deficiency / C5-9 deficiency: Neisseria infections.
