title: Intertriginous mycosis fungoides: a distinct presentation of cutaneous T-cell lymphoma that may be caused by malignant follicular helper T cells.
abstract: BACKGROUND
  Follicular helper T cells are a subset of helper T cells that facilitate B-cell recruitment and maturation. Rare cases of cutaneous T-cell lymphoma manifesting as de novo tumor lesions in intertriginous skin contain an infiltrate rich in B cells. These cases may represent malignant counterparts of skin-homing follicular helper T cells.
  
  
  METHODS
  Two men and 1 woman (age range, 35-58 years) were seen with predominantly intertriginous tumor-stage cutaneous T-cell lymphoma lesions characterized by the absence of epidermotropism and the presence of a mixed infiltrate rich in B cells. Two of the patients died of the disease less than 3 years from the initial diagnosis. The surviving patient has aggressive disease and underwent hematopoietic stem cell transplantation. Two of the patients had a prominent CXCL13+, Bcl6/CD3+, and programmed death protein 1-positive follicular helper T-cell population.
  
  
  CONCLUSIONS
  The intertriginous tumor variant of cutaneous T-cell lymphoma is heterogeneous but may be associated in some cases with a follicular helper T-cell immunophenotype. These patients may follow an aggressive clinical course. Tumor progression in sanctuary sites on patients receiving phototherapy may manifest as a similar clinical phenotype. Further characterization of the disease process is needed to confirm this observation.
authors.affiliation: Department of Dermatology, Northwestern University, Chicago, Illinois 60611, USA. bryan.gammon@gmail.com
authors.forename: Bryan
authors.initials: B
authors.lastname: Gammon
authors.forename: Joan
authors.initials: J
authors.lastname: Guitart
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D016410:Lymphoma, T-Cell, Cutaneous / Q000276:immunology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009182:Mycosis Fungoides / Q000276:immunology* / Q000473:pathology*; D012878:Skin Neoplasms / Q000276:immunology* / Q000473:pathology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology* / Q000473:pathology