Allergy / Immunology Flashcards
Antibody that has a major role in allergic conditions, e.g., anaphylaxis, atopy, asthma, allergic rhinitis, food allergies
IgE
Antibody that mediates type I hypersensitivity reaction
IgE
First antibody produced in an infection
IgM
An antibody found in body mucosal secretions
IgA
What is the prevalence of atopic disorders in children with one affected parent?
Up to 60%
What is the prevalence of atopic disorders in children with 2 affected parents?
Up to 80% (family history is critical in all atopic disorders)
What are atopic disorders?
Atopic dermatitis, asthma, allergic rhinitis, and food allergies
What are the indications of allergy testing?
Significant allergies, e.g., asthma, anaphylaxis, food or drug allergies, difficult to treat allergies or requirement for specific treatment
An infant with severe eczema and/or severe egg allergy
Evaluate for peanut reactivity with either skinprick testing and/or serum IgE levels, and if necessary, oral food challenge
Which allergy test is preferred in cases of dermatographism, generalized dermatitis, or a clinical history of severe anaphylactic reactions to a given food?
Radioallergosorbent test (RAST) (allergenspecific IgE antibody
Which allergy test is associated with a high false positive rate?
Both skin-prick testing and serum IgE levels
Child currently on diphenhydramine for allergies is scheduled for skin allergy testing. When should diphenhydramine be stopped?
At least 5days prior to testing
Child currently on cetirizine for allergies is scheduled for skin allergy testing. When should cetirizine be stopped?
At least 7days prior to testing
Child currently on amitriptyline for migraine headache prophylaxis is scheduled for skin allergy testing. When should amitriptyline be stopped?
At least 2weeks prior to testing
What is the first step that should be taken in the management of allergic rhinitis?
Avoidance or reduction of allergen exposures
The first-line pharmacologic treatment of allergic rhinitis
Intranasal steroids and/or second-generation oral antihistamines
Common complications of untreated allergic rhinitis
Recurrent acute otitis media, sinusitis, chronic cough, and asthma
Complications of prolonged use of nasal adrenergic drops
Rhinitis medicamentosa
An 8-year-old male presents with congestion, itchy nose, and watery eyes. Symptoms are exacerbated when playing with the pet cat. He loves his cat. What is the most effective treatment?
Avoid the trigger (e.g., by keeping the cat at least outside the bedroom or the house all the time; HEPA filters can help)
Child with a history of pollen allergy develops rapid onset of itching, swelling of the lips, mouth, and throat when eating raw fruits and vegetables. What is the most likely cause?
Oral allergy syndrome (OAS) (cross-reactivity with pollen)
What is the best treatment for OAS?
Avoid offending foods
How long do the allergies to peanuts, tree nuts, seafood, and fish last?
Lifelong allergies
How long do the allergies to milk, eggs, and soy last?
Most children outgrow by 5years of age
A 2-month-old exclusively breastfed infant is seen for bloody stools; weight gain is appropriate, and physical exam is normal
Reassurance (counsel mother to avoid dairy, soy, eggs for 2weeks, then re-evaluate)
Induration reaction to TB testing after 72h is an example of
Type IV: cell-mediated hypersensitivity
Allergy to contrast media is an example of
Non-IgE mediated
Child with a history of severe allergic reaction to radiographic contrast media is going for CT scan with IV contrast
Administer prednisone and diphenhydramine before injection or choose other alternative imaging tests
Child with a history of severe allergic reaction to seafood is going for an abdominal CT scan with oral and IV contrast. Does he or she need a pretreatment with prednisone and diphenhydramine?
No (iodine allergy is not a risk factor for allergic-type contrast reactions)
A 16-year-old male with a new watch notices an area of erythema located on the wrist where the watch was worn. No other lesions
Type 4—contact dermatitis, a delayed hypersensitivity reaction
What is the best treatment in cases of contact dermatitis?
Avoid offending agents
Child received penicillin 10days ago for the first time, presents with fever, nausea, vomiting, pruritic skin rash (urticaria), angioedema, joint pain, lymphadenopathy, myalgia, and proteinuria
Serum sickness
A common trigger of allergic reactions in a patient with spina bifida or congenital urogenital problems
Latex
What is the most common specific autoimmune association with chronic urticaria?
Autoimmune thyroid disease (laboratory evaluation should include thyroid-stimulating hormone (TSH) level and thyroid antibodies)
Sudden onset of lip swelling, abdominal pain, swelling of both feet, non-pruritic erythematous skin rash; one family member has the same condition
Hereditary angioedema
What is the cause of hereditary angioedema (HAE)?
Low levels or decreased function of plasma protein C1 inhibitor (C1-INH). (Autosomal dominant)
Initial screening test for a patient with suspected hereditary angioedema
C4 level most reliable and cost-effective screening test for HAE
The test that can differentiate between various types of hereditary angioedema
C1-INH functional assay
A 6-year-old male with yellow-tan macules located on the upper extremities. Parents notice localized erythema following scratching of the lesions and after taking a hot shower
Mastocytosis—Darier sign: urticaria after stroking lesions
Common diagnostic lab for mastocytosis
Elevated tryptase levels
A 15-year-old male presents with several erythematous, pruritic circumscribed lesions that occur with exercise
Exercise-induced urticaria
Child presents a few minutes after eating peanut butter with urticaria, skin flushing, pruritus, angioedema, rhinorrhea, wheezing, shortness of breath, abdominal pain, vomiting, diarrhea, lightheadedness. What is the next best step?
IM epinephrine to administer as quickly as possible
Child with a history of life-threatening reaction to a bee sting is coming to your office for a follow-up after he was discharged from the ER with EpiPen prescription. What is the next best step?
Referral to an allergist for immunotherapy
A 4-year-old male scheduled for a well child check; he was recently treated with a 5-day course of oral steroids for asthma exacerbation. Which vaccines can be given?
All vaccines including MMR and varicella
A 4-year-old male scheduled for a well child check; he has been treated with high dose steroids for 4weeks. Should the MMR and varicella vaccines be given?
No—patients receiving high steroids for greater than 2weeks should be off steroids for at least 1month
Child is being treated with intranasal steroids for allergic rhinitis. Should the MMR and varicella vaccines be given?
Yes
What is the best initial test for any child with suspected immunodeficiency?
Complete blood count (CBC)
Patient with recurrent meningococcal meningitis
The defect in terminal complement C5–C9 deficiency
Initial screening test for a patient with suspected complement deficiency, e.g., recurrent (Neisseria meningitidis) meningitis
(CH50) test
Complement deficiency that increases the risk of systemic lupus erythematosus
C2 deficiency
What is the best screening test for cell-mediated immunity associated with T-cell defects?
T-cell phenotyping (CD4/CD8, memory vs. naïve T cells) and T-cell proliferative responses
What is the best initial test for an infant with suspected humoral immune deficiency?
Immunoglobulin levels
An 8-week-old boy presents with diarrhea, pneumonia, persistent oral thrush, eczematous-like skin lesions, sepsis, lymphopenia, and failure to thrive
Severe combined immunodeficiency (SCID)
The enzyme deficiency that is found in SCID?
Adenosine deaminase deficiency
A 9-month-old boy, previously healthy, presents with recurrent otitis media, 2 episodes of pneumonia in the last 2months, persistent giardiasis. O/E: the lymph nodes, the tonsils are absent
X-linked agammaglobulinemia (usually starts after first 6months of life)
Adolescent presents with recurrent sinus and pulmonary infections due to encapsulated bacteria, malabsorption, hepatosplenomegaly, and low level of immunoglobulins (IgG, IgM, and IgA)
Common variable immunodeficiency
The best treatment for a child with asymptomatic transient hypogammaglobulinemia of infancy
Observation (no treatment is necessary)
An 8-year-old boy presents with eczema, recurrent Staphylococcus aureus skin infections without inflammatory response “cold abscess,” pneumatoceles, coarse facial features, eosinophilia, and IgE level is 80,000IU
Job syndrome (autosomal dominant hyper-IgE syndrome)
A 5-month-old presents with Pneumocystis jiroveci pneumonia, mouth ulcers, severe neutropenia, recurrent sinusitis, otitis media, chronic diarrhea, failure to thrive, and negative HIV
X-linked hyper IgM syndrome
A 4-year-old boy with recurrent skin abscesses, spleen and liver abscesses, and osteomyelitis
Chronic granulomatous disease (X-linked)
Test of choice in a patient with a suspected chronic granulomatous disease
DHR oxidation is preferred, NBT reduction can be used
Severe progressive infectious mononucleosis and Epstein–Barr virus (EBV) fulminant hepatitis
X-linked lymphoproliferative syndrome (Duncan syndrome)
Highly elevated WBC in a 10-week- old infant who still has an umbilical cord
Leukocyte adhesion defect type I
Test of choice in a patient with suspected leukocyte adhesion defect
Flow cytometry beta 2 integrin CD11b/CD18 on leukocytes
Newborn with hypocalcemia, tetralogy of Fallot, interrupted aortic arch, and abnormal facial features
DiGeorge anomaly (deletion of chromosome 22q11.2)
Recurrent ear infections, eczema, profuse bleeding during a circumcision procedure, thrombocytopenia, and small platelets
Wiskott–Aldrich syndrome
Persistent thrush, nail dystrophy, and endocrinopathies
Chronic mucocutaneous candidiasis
Short stature, fine hair, and severe varicella infection
Cartilage-hair hypoplasia with short-limbed dwarfism
Oculocutaneous albinism, recurrent infections, and easy bruising
Chédiak–Higashi syndrome
Candidiasis with raw egg ingestion
Biotin-dependent carboxylases deficiency
A 4-year-old with short stature, micrognathia, telangiectasia, immunodeficiency, learning disability, deficiency of DNA ligase I
Bloom syndrome
An 8-year-old boy presents with recurrent ear and sinus infections, ataxia, oculocutaneous telangiectasia, and elevated α1-fetoprotein
Ataxia–telangiectasia (autosomal recessive)
