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


Topic Completed: 1 July 2011

Revised: 26 March 2019

Copyright: 2002-2019, PathologyOutlines.com, Inc.

PubMed Search: Allergic contact dermatitis [title] skin
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Cite this page: Hamodat M Allergic contact dermatitis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skinnontumorallergiccontact.html. Accessed May 26th, 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

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