CONTACT DERMATITIS
Contact Dermatitis is one of the most common dermatological problems with irritating and annoying consequences in social life.While at office,at home and at social events with friends these consequences are the most disturbing one and produce uneasiness to scratch the irritating area in front of others.
Usually a foreign body touches your skin and enter into our body may produce antibodies to fight the invader.Mast cells are triggered to release various inflammatory chemical such as histamine and ecosanoids to express the body its inconvenience by its own languages such as itching edema infammations etcetc.
There are wo type of contact dermatitis as follows:-Usually a foreign body touches your skin and enter into our body may produce antibodies to fight the invader.Mast cells are triggered to release various inflammatory chemical such as histamine and ecosanoids to express the body its inconvenience by its own languages such as itching edema infammations etcetc.
A.Irritant Contact Dermatitis is caused by direct contact with a primary irritant and the primary irritants are of the types as follows:-
1.Absolute Primary Irritants These are corrosively skin damaging substances such as strong acids,alkalis and similar industrial chemicals
2.Relative Primary Irritants These are the most common cases of contact dermatitisseen in clinical practices.These irritants are less toxic than absolute primary irritants and they require repeated frequent contacts to establish a dermatitis.(e.g)soaps,detergents benzoylperoxide and some plants
B.Allergic Contact Dermatitis These are the worst annoying
and irritating skin conditions.Almost most of the things which are
allergic to the skin can produce this dermatitis.Some plants,many chemicals,can cause allergic contact dermatitis.The best
example is the contact dermatitis produced by poison ivy plant.The
plant produces on contact with our skin a peculiar type of reaction
mediated by T-Cells(T-lymphocytes) a type of WBC circulating in our
blood through the lymphatic system and need the following sequence of events must occur to provoke it.
a)The skin epidermis must come in contact with the allergen (the hapten)b)Thereby a hapten-epidermal protein complex must form as the antigen
c) The antigen must enter into the lymphatic system
d)Immunologically competent lymphatic cells must be formed which are selectively active against the invading antigen
e) In this condition if a second contact between the skin epidermis and a hapten occurs then the incidence of contact dermatitis starts.
f)The duration between the first contact and the second contact is known as the induction period and it may last for 4 to several weeks.Once the induction period completed a minute second contact will produce a severe eczema with an onset of 12 hrs and attain the peak at 48 hrs to 72 hrs after exposure.
Once the sensitivity is fully developed it will last for life
Most contact allergens produce sensitization only to a small populations except the poison ivy which produces sensitization to almost 99% of the populations,who come in contact with it.
PHASES OF CONTACT DERMATITIS
1.Acute Stage Wet lesions such as leaking blisters,weaping skin,erythema,edema, vesicles and oozing.
2.Sub Acute Stage Crusts and scabs form over the already wet lesions.Allergic contact dermatitis and irritant contact dermatitis caused by absolute primary irritants such as strong chemical can produce both acute and sub acute stages.
3.In this stage initially the lesions become dry and thickend to form fissures.Later erythema,lichenification,and excoriations appear.This stage occurs mostly with irritant contact dermatitis caused by relative primary irritants.
Allergen Producing Plants 1.Poison ivy;2.Poison oak 3.Poison sumacIn all the above plants a previous contact must be necessary to produce swensitization to form dermatitis by the second one.
In most of these poisonous plants the main sensitizing agent is an oleo resin known as urushiol oil
The plants must be bruised or crushed inorder to contact with the oleoresin which is presen in the roots,stems,leaves and fruits.
The oleoresin can remain in tools, toys, cloths,pets and fingernails for longer time if these items comes in contact with the bruised poison plants.
urushiol oil is not volatile if a person sits simply nearby the plant without touching it will not get contact dermatitis
But in a burning plant the oleoresin droplets may be carried by the smokes and get deposited in our skin to produce the dermatitis.
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