title: The clinical and histopathologic spectrum of "dermal hypersensitivity reactions," a nonspecific histologic diagnosis that is not very useful in clinical practice, and the concept of a "dermal hypersensitivity reaction pattern".
abstract: BACKGROUND
  "Dermal hypersensitivity reaction" (DHR) is diagnosed by dermatopathologists but is not an accepted clinical disease entity. There are no clear guidelines for its diagnosis, differential diagnosis, or management.
  
  
  OBJECTIVE
  The objectives were to define the histologic criteria for cases histologically diagnosed as DHR and identify corresponding clinical disorders.
  
  
  METHODS
  Skin biopsy specimens from 130 patients diagnosed as "consistent with DHR" were reviewed. Additional information was obtained from patients, their dermatologists, and medical records.
  
  
  RESULTS
  Follow-up in 74 of 110 patients (median, 26.6 mo) revealed, most commonly, diagnoses of urticaria, drug reactions, and spongiotic (eczematous) dermatitis. Among the remaining cases, 37 of 59 reported persistence of disease, some exhibiting a uniform phenotype characterized by excoriated, edematous papules on the trunk. Histopathologic features present in more than 90% of 143 biopsy specimens included superficial and mid-perivascular lymphocytic infiltrates with eosinophils.
  
  
  CONCLUSIONS
  DHR is a perivascular lymphocytic dermatitis with eosinophils involving the papillary and upper reticular dermis and minimal, if any, primary epidermal alteration. The term DHR does not represent any known clinical disorder; rather, it corresponds to many clinical disorders. The use of the phrase "dermal hypersensitivity reaction pattern" may be helpful in conveying the idea that a particular histologic pattern may be seen in a number of clinical disorders.
authors.affiliation: Department of Dermatology, University of Connecticut School of Medicine, Farmington, USA. maxwell.fung@ucdmc.ucdavis.edu
authors.forename: Maxwell A
authors.initials: MA
authors.lastname: Fung
mesh_terms: D000328:Adult; D000368:Aged; D001707:Biopsy, Needle; D046508:Culture Techniques; D003876:Dermatitis, Atopic / Q000276:immunology / Q000473:pathology*; D003937:Diagnosis, Differential; D003875:Drug Eruptions / Q000276:immunology / Q000473:pathology*; D004485:Eczema / Q000276:immunology / Q000473:pathology; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology / Q000473:pathology*; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012042:Registries; D012189:Retrospective Studies; D014581:Urticaria / Q000276:immunology / Q000473:pathology