- Human pathology

Home > E. Pathology by systems > Skin > contact dermatitis

contact dermatitis

Saturday 9 April 2022

allergic contact dermatitis


Definition : T cell-mediated delayed (type IV) hypersensitivity reaction to allergens from skin contact.

Contact dermatitis results from either exposure to allergens (allergic contact dermatitis) or irritants (irritant contact dermatitis).

Phototoxic dermatitis occurs when the allergen or irritant is activated by sunlight.


- Acute stage :

- Subacute stage :

- Chronic stage :

  • marked acanthosis
  • hyperkeratosis with or without parakeratosis
  • minimal epidermal edema

- Langerhans cell microabscesses can be associated with allergic contact dermatitis (ACD) but are a nonspecific finding

See also

- cutaneous diseases