Skin inflammatory (nontumor)
Spongiotic, psoriasiform and pustular reaction patterns
Allergic contact dermatitis

Author: Mowafak Hamodat, M.D., M.Sc. (see Authors page)

Revised: 15 October 2018, last major update July 2011

Copyright: (c) 2002-2018,, Inc.

PubMed Search: Allergic contact dermatitis [title] skin

Page views in 2018: 6,609
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Cite this page: Hamodat, M. Allergic contact dermatitis. website. Accessed January 22nd, 2019.
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

Microscopic (histologic) 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
Microscopic (histologic) images

Images hosted on other servers:

Various images

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