Immunology

Question 1

dx
Urticaria
Hives
Angioedema

Answer 1

• Urticaria: hives and/or angioedema
• Hives: must be histaminergic
• Angioedema only = histaminergic (more common) or bradykinergic (more dangerous)

Question 2

Angioedema only
what features to look for

Answer 2

Question 3

Urticaria and angioedema ddx histaminergic

Answer 3

• Allergic tyep 1 hypersensitivity reaction e.g. foods, drugs, venom. Mostly IgE mediated reactions
• Spontaneous or autoimmune urticaria and angioedema (CSU) is much more common
• Inducible urticaria and angioedema

Rarer
* Urticarial vasculitis
* Autoinflammatory syndromes

Question 4

Angioedema only without wheals

Answer 4

• Most common: ACEi induced angioedema (need to exclude this first). Stop ACEi for 3 weeks
• Hereditary angioedema (rarer): reduced level or function of C1 esterase inhibitor. Absent C4 (used for screening), low C1 esterase inhibitor level or function (can test)
• Acquired C1 esterase inhibitor (1:100,000: can be paraneoplastic phenemenon

Question 5

Most common cause of urticaria
Tx flowchart

Answer 5

Chronic spontaneous urticaria
* Chronic: at least 6 weeks
* Spontaneous = not allergy (not reactive)
* Urticaria = hives and/or angioedema

Autoimmune condition, autoAb vs mast cells or cross link IgE
Leads to mast cell degranulation (i.e. histaminergic)
Can present with angioedema only (uncommon)

2nd gen antihistamine: cetirizine, loratidine

Question 6

Primary vs secondary immunodeficiencies

Answer 6

Question 7

History taking of immunodeficiencies

Answer 7

Question 8

Pathogens that affect predominantly humoral defect (antibody B cell) or cellular defect (T cell)

Answer 8

Question 9

Timing of allergy causes

Answer 9

Question 10

Ix for drug allergy based on timing of reaction

Answer 10

Question 11

dx anaphylaxis (type 1)

Answer 11

• Acute (immediate type)
• Multi system (cardiopulmonary involvement)
• Life threatening

Most common: food dependent excercise induced anaphylaxis (most common cause of food anaphylaxis in HK) caused by wheat

Question 12

Mx of anaphylaxis

Answer 12

• Appropriate avoidance
• IM/SC adrenaline is 1st treatment for anaphylaxis
• Steroids/antihistamines/bronchodilators are adjuncts only
• Acute serum tryptase taken within 1-6 hours
• Baseline tryptase should be taken >24 hours after event
• Significant elevation = 20% +2 rule (on top of baseline tryptase)
• Prescribe AAI and refer to immunology and allergy

Question 13

What are the type 4 SCAR reactions?

Answer 13

SJS: skin peeling off, mucosal involvement
DRESS (late onset): systemic symptoms
AGEP: rapid onset

Question 14

RA
Peak age of onset
Pattern
Serological tests
XR
Classical deformity

Answer 14

Question 15

RA tx

Answer 15

TNFa inhibitor: adalimumab, etanercept, infliximab
CTLA4 inhibitor: abatacept
CD20 inhibitor: rituximab
IL6 inhibitor: tocilizumab

Question 16

Spondyloarthritis
Age of onset
Pattern
Other clinical features
Blood tests
Imaging findings
ASAS criteria for axial SpA
Pharmacological tx

Answer 16

Question 17

Spondyloarthritis PE

Answer 17

Question 18

Gout common triggers
definitive dx
Arthrocentesis
Tx

Answer 18

Question 19

SLE biomarkers

Answer 19

Question 20

SLE criteria

Answer 20

Question 21

SLE tx

Answer 21

Question 22

Small vessel, medium vessel and large vessel vasculitis causes

Answer 22

Question 23

Giant cell arteritis type
Clinical features
Ix
Tx

Answer 23

Question 24

Takayasu arteritis type
Who is affected
Symptoms
Clinical features
Ix
Tx

Answer 24

Question 25

Polyarteritis nodosa (what type of vasculitis) Clinical features Ix Tx

Answer 25

Question 26

Use of ANCA in ANCA associated small vessel vasculitis

Answer 26

Question 27

Types of ANCA associated vasculitis

Answer 27

Question 28

Who is affected by IgA vasculitis (small vessel vasculitis)? Classical triad?

Answer 28

## Footnote Tx: NSAID for arthritis, glucocorticoids for GI