Skin-nontumor / Clinical dermatology
Other dermatoses
Allergic contact dermatitis

Author: Mowafak Hamodat, M.D., MB.CH.B, MSc., FRCPC (see Authors page)

Revised: 21 June 2016, last major update July 2011

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Allergic contact dermatitis [title] skin

Definition / General
  • Due to topically applied antigens, such as poison ivy or nickel, which cause delayed hypersensitivity reaction with itching or burning
  • Dermatitis occurs at site of contact
  • Antigens are initially taken up by Langerhans cells and carried to lymph nodes
  • Upon reexposure, cytokines are released, causing endothelial activation and adherence of memory T cells, which release lymphokines, causing spongiotic dermatitis
  • May get bacterial superinfection (impetiginization)
Case Reports
Clinical Images

Images hosted on other servers:

Linear demarcation due to textile dyes

Due to hair dye

Micro Description
  • Extensive spongiosis, initially acute spongiotic dermatitis, evolving into subacute or chronic spongiotic dermatitis, which then resolves
  • May have intraepidermal vesicles, exocytosis, papillary dermal edema or perivascular lymphocytic infiltrates in upper dermis, also numerous eosinophils
Micro Images

Images hosted on other servers:

Various images



Psoriasiform epidermal hyperplasia with spongiosis and parakeratosis;
superficial perivascular infiltrate of lymphocytes and eosinophils with exocytosis