Paucity of intraepidermal FoxP3-positive T cells in cutaneous T-cell lymphoma in contrast with spongiotic and lichenoid dermatitis

J Cutan Pathol. 2010 May;37(5):535-41. doi: 10.1111/j.1600-0560.2009.01381.x. Epub 2009 Aug 7.

Abstract

Background: FoxP3 is the most specific available marker for regulatory T cells (Tregs). Tumor-associated FoxP3-positive Tregs have been identified in various neoplasms, including cutaneous T-cell lymphoma (CTCL). FoxP3 expression in CTCL varies across groups; few studies have compared CTCL with inflammatory conditions.

Methods: Lesional skin biopsies from 20 patients with CTCL [13 mycosis fungoides (MF); 7 Sézary syndrome (SS)] and 22 with inflammatory dermatoses (11 spongiotic; 11 lichenoid or interface) were examined for FoxP3 expression by immunohistochemistry. Epidermal FoxP3-positive lymphocytes were counted as a percentage of the total epidermal CD3-positive T-cell population.

Results: FoxP3-positive T cells composed the minority of infiltrate in all major categories. Lower numbers of epidermal FoxP3-positive T cells were observed in CTCL, particularly MF, than in inflammatory dermatoses (P < .001). CTCL neoplastic T cells did not express FoxP3.

Conclusion: FoxP3-positive T cells are less frequently encountered in MF than in inflammatory dermatoses. FoxP3-positive T cells occur in higher proportions in the dermis than in the epidermis and probably correlate with coexisting inflammatory components. CTCL neoplastic cells do not typically express a Treg phenotype and are associated with low numbers of FoxP3-positive Tregs in the infiltrate. FoxP3 expression by immunohistochemistry may aid histologic evaluation of these conditions.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Cell Count
  • Dermatitis / metabolism*
  • Dermatitis / pathology
  • Forkhead Transcription Factors / metabolism*
  • Humans
  • Immunohistochemistry
  • Lichenoid Eruptions / metabolism*
  • Lichenoid Eruptions / pathology
  • Mycosis Fungoides / metabolism*
  • Mycosis Fungoides / pathology
  • Sezary Syndrome / metabolism*
  • Sezary Syndrome / pathology
  • Skin / metabolism
  • Skin / pathology
  • Skin Neoplasms / metabolism*
  • Skin Neoplasms / pathology
  • T-Lymphocytes / metabolism
  • T-Lymphocytes / pathology

Substances

  • FOXP3 protein, human
  • Forkhead Transcription Factors