Allergy/Immunology Flashcards
Angioedema - classification by mechanism
+Urticaria –> activation of mast cells –> IgE mediated, direct mast cell activation, or non-IgE mediated
-Urticaria –> unknown or generation of bradykinin –> hereditary or acquired
Diagnosis to r/o for delayed umbilical cord seperation
Leukocyte adhesion defect (type 1)
Common bugs and presentations suggestive of phagocytic (neut) defects
Bugs = catalase positive organisms (aspergillus, S. aureus) Prez = umbilical separation delay, poor wound healing, severe gingivitis, SSTI, solid organ infection
Dx - potentially life threatening, non-pruritic swelling (with no urticaria), and recurrent abdominal pain
Hereditary C1 inhibitor deficiency = recurrent angioedema to face/body, GI tract, and airway
Common bugs and presentation for complement defect immunodeficiency
- Bugs = encapsulated organisms (Neisseria*)
- Prez = rheum disorders/autoimmune, increased susceptibility to infection, angioedema
Mneumonic for hypersensitivity reactions
ACID = acute, cytotoxic, immune complex mediated, delayed
4 types of hypersensitivity with x1 example
- Type 1: IgE, anaphylaxis
- Type 2: IgG/IgM cytotoxic, hemolytic anemia
- Type 3: Immune complex mediated, serum sickness/SLE
- Type 4: T-cell, SJS
When (timing wise) is the best time to swab an asymptomatic neonate following C/S for a mother with HSV lesions?
> 24 hours from birth
Spectrum of presentations for a parvovirus infection
- Asymptomatic
- Erythema infectiosum (5th disease, slapped cheek)
- Transient aplastic crisis with hemolytic anemia
- Chronic anemia in child with immunodeficiency
- Hydrops fetalis
- Arthritis/arthralgia
GAS pharyngitis - tx of choice, duration, when child can go back to daycare?
10 days of penicillin or amox
-Go back after 24 hours of Abx
GAS pharyngitis - time window when can treat with Abx
For 9 days since onset of symptoms
GAS pharyngitis - why treat with Abx
- Shorten illness course
- Prevent ARF
- Prevent suppurative complications
- Decrease spread of infection
Scarlet fever - what is rash caused by and how does the rash present?
- Caused by strep pyrogenic exotoxin
- Begins on neck, face, and upper trunk then spreads to rest of body within 1-2 days
- Palm/sole sparing
- Sandpaper texture, erythematous, blanchable papules
- Pastia lines =erythema in skin folds
- Desquamation in 5-7 days
Indications for tonsillectomy
- OSA secondary to adenotonsillar hypertrophy
- Recurrent throat infection: >7 past year, >5 last 2 years, >3 last 3 years
- History of peritonsillar abscess
- Multiple Abx allergy/intolerance
- PFAPA
Basic screen of labs for immunodeficiency (x7)
- CBC
- Immunoglobulins
- Complement: CH50, C3, C4
- Vaccine titres
- Infectious w/u
- Immunodeficiency panel
- CXR
x9 red flags for immunodeficiency
- 4 or more AOM in 1 year
- 2 or more serious PNA in 1 year
- 2 or more serious sinus infection in 1 year
- 2 or more deep seated infections
- Recurrent deep skin or organ abscesses
- Recurrent thrush when >1 year of age
- Required IV Abx to clear infections +/- >2 months total of Abx with little effect
- FTT
- Family history
Clinical presentation for IgE Syndrome
- Coarse facial features
- Atypical eczema
- Recurrent infections - S.aureus, PNA with pneumatoceles
- Delayed tooth exfoliation
Common bugs for B-cell deficiency (x6)
- Gram pos + neg bacteria, encapsulated
- Giardia
- Cryptosporidium
- Mycoplasma
- Enterovirus
- Campylobacter
Classic presentation for B-cell deficiency + other symptoms
- Sinopulmonary infections
- Bronchiectasis unexplained
- Other: malabsorption, diarrhea, ileitis/colitis, arthritis
Bugs + presentation of predominant T-cell disorder
- Bugs = viruses, fungal
- Presentation = oral candidiasis, opportunistic infections, other (GVHD, FTT, skin rash, sparse hair)
x2 examples of Ab-deficiencies (humoral or B-cell)
- Common variable immunodeficiency
- X-linked agammaglobulinemia
x5 examples of combined deficiencies
- SCID
- Wiskott-Aldrich Syndrome
- 22q11 deletion syndrome
- Hyper IgM syndrome
- Ataxia telangiectasis
x2 examples of phagocytic defects
- Chronic granulomatous disease
- Leukocyte adhesion defect
Secondary causes for recurrent infections
- Meds: steroids, chemo, anti-epileptics
- Infection: HIV, TB, measles, influenza, herpes group
- Structural: anatomic, impaired membrane integrity, immotile cilia, CF, indwelling catheter
- Malignancy: lymphoma, leukemia, solid tumors, myeloma
- Other: DM, renal insufficiency, PLE, malnutrition, lymphangiectasia, asplenia
Work-up for humoral assessment
- Number: lymphocyte subsets (flow cytometry) + immunoglobulins (check albumin to screen for secondary loss)
- Function: Vaccine titres, isohemagglutinins (IgM Ab to blood group A/B)
Work-up for cellular assessment
- Number: lymphocyte total count and subsets
- Function: specialized testing
Work-up for phagocytic assessment
- Number: neutrophil number
- Function: adhesion markers (CD11+CD18 for leukocyte adhesion defect), neutrophil oxidative burst index (for CGD)
Work-up for complement assessment
- Number: C1 esterase inhibitor levels
- Function: total hemolytic complement (CH50), alternate pathway (AH50), C1 esterase inhibitor function
X-linked agammaglobinemia: what is it and when does it present
- Caused by mutations in the tyrosine kinase that is important for B cell maturation
- Absent B lymphocytes in peripheral blood = no Ig production
- Presents 6-24 months when maternal IgG disappears
What to look for on exam in X-linked agammaglobinemia?
No tonsils or LNs
What will you find on Ix for X-linked agammaglobinemia?
- No B cells
- No immunoglobulins
- No Abs to vaccines
Therapy for X-linked agammaglobinemia?
IgG replacement for life
What are children with X-linked agammaglobinemia at risk for?
Bronchiectasis
What are the x3 classic features of Common Variable Immunodeficiency?
- Recurrent sinopulmonary infections
- Autoimmunity
- Malignancy
Difference on exam between Common Variable Immunodeficiency and XLA?
Presence of lymphatic tissue in CVID
What do labs show in Common Variable Immunodeficiency?
- Number: Decreased serum IgG, variable B cells
- Function: absent/reduced Ab vaccines, low isohemagglutinins
What is SCID?
Profoundly defective T + B cell function
When does SCID present?
2-6 months old
Are LN’s and tonsils present on exam in SCID?
No
What would Ix show in SCID?
- CXR: no thymus
- Lymphopenia with low/absent T cell function
- Absent Ab to vaccines
Mgmt for SCID
- New immune system = HSCT, gene therapy
- Prevent/tx infections = Abx, PJP proph, protective isolation, immunoglobulin replacement tx, blood products (CMV neg + irradiated), avoid live vaccines
Triad for Wiskott-Aldrich Syndrome
- Thrombocytopenia
- Eczema
- Recurrent infections
What would investigations show for Wiskott-Aldrich Syndrome
- Number: thrombocytopenia (small), eosinophilia, +/- lymphopenia, variable IgG, low IgM, high IgA/IgE
- Function: poor Ab response to some vaccines, decreased T cell function
Management for Wiskott-Aldrich Syndrome
- Immunoglobulin replacement therapy
- PJP prophylaxis
- HSCT
- Monitor for autoimmune/malignancy
What autoimmune conditions (x3) are associated with Wiskott-Aldrich Syndrome?
- Hemolytic anemia
- Vasculitis
- IBD
What malignancies (x2) are associated with Wiskott-Aldrich Syndrome?
- B cell lymphoma
- Leukemia
What immunodeficiency must you rule out in a patient with PJP?
SCID
What to think of with ataxia + lymphoma?
Ataxia telangiectasia
Where to look on exam for telangiectasia in AT?
Conjunctiva, ears, face
Mode of inheritance for ataxia telangiectasia
Autosomal recessive
What immunodeficiency do you need to avoid ionizing radiation?
Ataxia telangiectasia
What malignancy are patients with Ataxia telangiectasia most at risk for?
Lymphoma
What x1 lab is specific for Ataxia telangiectasia?
Increased AFP
What immunodeficiency has progressive neurodegeneration?
Ataxia telangiectasia
What part of the immune system is impacted in Ataxia telangiectasia?
T-cell (cellular)
What organisms to think of for Chronic Granulomatous Disease?
Catalase positive = S. aureus, aspergillus, serratia, burkholderia, salmonella
What autoimmune condition is associated with Chronic Granulomatous Disease?
IBD
What would investigations show for Chronic Granulomatous Disease?
- Normal number of neutrophils
- Abnormal function on oxidative burst
Features of Hyper IgE syhndrome
- Recurrent abscesses in skin + lungs from S. aureus
- Mucocutaneous candidiasis
- Eczema
- Delayed shedding of primary teeth
- Bone #, scoliosis, joint laxity
What would you find on labs for hereditary angioedema?
-Deficiency in C1 inhibitor
Mode of inheritance in hereditary angioedema
Autosomal dominant
What is the more likely cause (rather than a B-lactam allergy) for maculopapular exanthems in children?
Viral infection
Type 1 immune reaction
- IgE mediated
- <2 hours to symptoms
Type 2 immune reaction
- Cytotoxic
- 10h to a week to symptoms
- Anemia, thrombocytopenia
Type 3 immune reaction
- Immune complex
- 1-3 weeks to symptoms
- Serum sickness-like reaction
Type 4 immune reaction
- T-cell mediated
- 2-14 days
- SJS, DRESS
What is the gold standard for ruling out a beta-lactam IgE-mediated allergy - when thought to be unlikely
Provocative drug challenge
Serratia - what immunodeficiency do you think of?
CGD
Most common use of immunotherapy?
Bee sting allergy
Match C3 deficiency and C5 deficiency with (a) early vs late complement component and (b) associated with autoimmune vs meningococcal
C3 - early, autoimmune
C5 - late, meningococcal
What immunoglobulin deficiency has an increased risk of anaphylaxis with IVIG?
IgA
Most common food allergens
- Wheat
- Fish
- Shellfish
- Peanuts
- Tree nuts
- Sesame
- Soy
- Milk
- Egg
x2 ways to test allergies
- Skin prick testing
- IgE blood test = RAST
What is the benefit of RAST vs skin prick testing?
Can stay on medications like montelukast
Tx for serum sickness like reaction
- Stop offending agent
- PO steroids
Presentation of serum sickness like reaction
- Rash
- Arthralgia
- Fever
- Edema
- LAD
- No mucous membrane involvement
What are the x2 indications for allergy testing and possible immunotherapy for insect venom reaction/allergy?
- If airway involvement
- If anaphylaxis
-Otherwise, do not refer for urticaria or localized reaction
What is the most effective use for immunotherapy in setting of allergies?
Bee sting allergy
Most important aspects of FPIES management
- IV fluid resuscitation
- Ondansetron
- Strict avoidance
x2 main types of mastocytosis
- Cutaneous
- Systemic
Derm sign for cutaneous mastocytosis
Darier’s sign
Lab finding in systemic mastocytosis
Elevated serum tryptase
Physical exam findings of allergic rhinitis
- Allergic shiners
- Dennie-Morgan lines
- Transverse nasal crease + allergic salute
- Allergic faces = high-arched palate, open, dental malocclusion
What medications to avoid with hereditary angioedema?
No OCP or ACEi’s
What test to do for hereditary angioedema?
C1 esterase inhibitor levels + function
What is characteristic of a rituximab specific serum sickness reaction?
Palpable purpura along lateral aspect of feet
Serum sickness management
- Remove inciting agent
- Supportive care
- Antihistamines
- NSAIDs
- Analgesics
- If severe = steroids
What may you see on labs in serum sickness?
- Thrombocytopenia
- Proteinuria
- Elevated CRP/ESR
- Decreased C3/C4
What PID do you think of with serratia?
CGD
What PID do you think of with N.meng?
Complement
What is the dx = hilar lymph nodes, eosinophilia, elevated Ca, elevated ALP?
Sarcoidosis
What is the component that is affected in penicillin allergy?
Minor component
What does a candida skin test do?
Test T-cell function
What organ does chronic GVHD not affect (entirely…may be some unhappiness but no dysfunction)? …oh RC questions
Liver
