Pathology EMQ template.

Name: Yuen Sau Tham

Theme: Allergy

 

OPTION LIST

 

A	Schromboid reaction	I	Acute Urticaria(TLR4 stimulation)
B	IgE Mediated Allergic Reaction	J	Systemic mastocytosis(C-Kit Mutation)
C	Drug-induced angioedema	K
D	Chronic urticaria	L
E	Asthma	M
F	Lactase deficiency	N
G	Sulphite sensitivity	O
H	CI esterase inhibitor deficiency	P

 

 

For each scenario below, choose the most appropriate answer from the list above. Each option may be used once, more than once or not at all.

 

1. A 45 year old man with known chronic asthma presents in A&E with Difficulty in breathing, swallowing, dizziness, vomiting and a flushed face. He had just gone for a reception which served lots of preserved food

 

2. A 7 year old boy was taken to his GP by his mother who was concerned that he had been getting very obvious swelling at areas where he scratches himself. She also said that he gets these swellings even when he bumps himself on objects(tables, chairs)

 

 

3. A 14 yr old child with history of childhood asthma and eczema complains of diahorrea and stomach cramps after 3 hours after drinking a Milk shake given to her by her friend.

 

 

4. During a house party, a 14 yr old child with history of childhood asthma and rhinitis complains of itchiness in mouth, difficulty after drinking some milk shake passed to her by her friend.

 

 

5. A 15 year old child presents with large areas of raised erythematous, edematos swelling on his arms and trunk. Mother says that he had just recovered from a “cold” where he had a bad sorethroat and fever.

 

6. A 49 year old afro-carribean lady presents with a swollen tongue and lips. When you ask her about her past medical history, she tells you that she recently been diagnosed with high blood pressure by her GP and is being seen for it.

 

ANSWERS

1. G

2. J

3. F

4. B

5. J

6. I

 

Explanations:

 

1.Sulphite sensitivity

Sulphite is an anti-oxidant used as preservative.

1:100 ppl are sensitive.

5% asthmatics react.

Uncommon in non-atopic asthmatics.

Sulphur dioxide produced in stomach goes up the to the trachea from stomach, causing bronchospasms + asthma symptoms( remember that asthmatics have BHR and react to non-specific stimuli-e.g. cold etc)

 

Clinical features:

-          Bronchospasm(wine sensitive asthma)

-          Flush/feeling temperature change

-          Vomit

-          Difficulty swallowing

-          Dizziness

-          Contact dermatitis

 

2.C-Kit mutation(àsystemic mastocytosis)

D816V Point mutation of the C-kit receptor(which detects stem cell factors(SCF))à allows auto-phosphorylation of itself(has auto-tyrosine kinase ability) àenhance mast cell proliferation + degranulation

Patient can get “rash”(actually mast cell aggregates) that looks like urticaria, which, when scratched/impacted lightly, results in a huge stimulation/activation of mast cells.

 

3. Lactase Deficiency

Take into account the time lag after consumption of possible trigger. IgE mediated allergic reactions usually presents with symptoms within minutes and normally a small amount(1/2 a peanut.) would be able to cause an allergic reaction. In this case, symptoms presented after 3 hours, so may not be an IgE mediated allergy. In this case, it is a metabolic cause where lactase deficiency results in milk intolerance and hence the symptoms. Note that this is NOT allergy, just enzyme deficiency

 

4. IgE Mediated Allergic Reaction

Classic past medical history of the allergic march( Eczema before Food allergy, before rhinitis, before asthma). Symptoms and time lag highly suggestive of allergic reaction, IgE mediated. (refer to lactase deficiency above)

 

5. TLR4 stimulation(àacute urticaria)

TLR4 on mast cells get activated by microbial components(e.g. LPS)

e.g. person with acute urticaria after having a streptococcal throat infection/URTI

Drug induced

In this case, clue was that she was recentlty diagnosed with high blood pressure and she has been started on ACE-inhibitors.

Bradykinin is broken down by 3 enzymes, one of which is ACE.

Therefore, administration of ACE-I would cause bradykinin to build up in system and cause angioedema.

e.g. lingual angioedema(> common in African Americans)