FA derm mistake?

[MissMedicine]

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Hey peeps

Is there a mistake on pg 258 of FA that calls atopic dermatits/aka allergy dermatitis (NOT contact dermatitis) a Type IV reaction. Pg 364 of BRS says this is a type 1 rxn... which makes sense to me, and contact dermatitis (chemicals) a type iv rxn. 😕 ????

 

[bigfrank]

Contact dermatitis is always a Type IV (Delayed-Type) Hypersensitivity. If you'll re-read the BRS section you believed stated it was type I, you will find that while these skin manifestations typically occur in individuals with Type I systemic disease (atopic asthma for example), the skin findings are Type IV, "rather than type I."

The only true Type I HS skin reactions are hives and the local "wheal and flare" following a scratch.

 

[MissMedicine]

I am not talking about Contact dermatitis. yes thats type 4. But atopic dermatitis is type I (there is even a q on q bank on this) but first says ATOPIC DERMATITIS is type 4

 

[bigfrank]

To quote from BRS to answer your question (pg. 364)...

Atopy (allergy). Eczematous dermatitis frequently occurs in persons with type I anaphylactic-type hypersensitivitities, such as hay fever or bronchial asthma; however, the skin manifestations in these atopic patients are most often caused by type IV rather than type I Hypersensitivity."

 

[MissMedicine]

yeah it seems like their skin manifestations are usually type iv. ok, thanks big frank!

 

[Gswami]

Remember it says most often, so the big thing to look at is if it gives the histology of the cells involved or the time it took for the reaction to occur

 

[MissMedicine]

right,bc i think the qbank question that called it type i atopic dermatitis was rapid onset.

 

[mountaindew2006]

😕

ok so let me just clarify/make sure.

INITIALLY (as in very acute part) when you have bronchspasm, etc it would be considered TYPE 1 , in particular atopic dermatitis

however, later on i guess if you have some skin rash that appears its considered type 4.

so bottom line, the 'wheal and flare' even though thats a 'skin' manifestation you considered it as type 1 atopic dermatitis??

 

[MissMedicine]

ok if i understand it correctly based on combining brs, fa, and the qbank q, the systemic effects (vasodilation) of atopic dermatitis are type 1, the skin manifestations can ALSO be type i if the question stem says something like rapid onset erythematous rash.... if it's delayed then the skin manifestation is 4. so basically the skin manifestations of atopic dermatitis can be type 1 or 4 based on the onset.... correct me if im wrong

 

[mountaindew2006]

yah thats wht i'm thinking from wht has all been said.. 😎