Dermatology Made Simple : Exogenous Eczema / Contact Dermatitis

Contact Dermatitis:

This occurs due to allergic reaction in the skin due to exposure to allergens both environmental and occupational.

The likelihood of developing an allergy is directly proportional to increased exposure to a potential allergen.

The incidence of irritant dermatitis is further increased in patients who have skin with disturbed barrier function.

An allergic reaction develops at site of sensitization to an allergen.Even if the allergen affects another skin site later,the patient would still get eczema on the previous site of exposure to allergen.

Clinical features of contact dermatitis:

There would be the following features in Acute Reactions:

Erythema (Redness)

Pruritis (Itching)

Oedema (Swelling)

Vesicle formation

In chronic dermatitis there would be thickening of the skin (Lichenification)

Some examples of contact allergens causing contact Dermatitis:

Cobalt and Nickel (In jewellry)

Perfumes

Formaldehyde

Paraphenylenediamine : found in tattoos