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

Topic Completed: 1 July 2011

Minor changes: 8 April 2021

Copyright: 2002-2021,, Inc.

PubMed Search: Allergic contact dermatitis [title] skin

Mowafak Hamodat, M.B.Ch.B., M.Sc.
Page views in 2020: 7,722
Page views in 2021 to date: 2,892
Cite this page: Hamodat M. Allergic contact dermatitis. website. Accessed April 14th, 2021.
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:

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

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