title: Granular parakeratosis: a case report and literature review.
abstract: BACKGROUND
  Granular parakeratosis is suspected to result from an error in epidermal differentiation, leading to variably pruritic, hyperpigmented-to-erythematous patches and plaques. Characteristic histopathologic features include a thickened stratum corneum, compact parakeratosis with retention of keratohyalin granules, vascular proliferation, and ectasia. The pathogenesis of this entity is uncertain.
  
  
  METHODS
  We present a case of axillary granular parakeratosis and review the literature.
  
  
  RESULTS
  The lesion showed a thickened stratum corneum with compact parakeratosis, slight epidermal hyperplasia, and a sparse perivascular lymphohistiocytic infiltrate. Keratohyalin granules were diffusely present within the parakeratotic stratum corneum, and the retained granular layer showed focal vacuolization.
  
  
  CONCLUSIONS
  Granular parakeratosis is a rare form of parakeratosis most often seen in the axilla, although other intertriginous areas may be affected. Unique histopathologic findings allow for a specific diagnosis to be made. Although an irritant contact reaction appears causative, mechanical irritation may also play a role in inducing these skin changes.
authors.affiliation: Department of Dermatology, Wake Forest University Baptist Medical Center, Winston-Salem, NC, USA.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Wallace
authors.forename: Rita O
authors.initials: RO
authors.lastname: Pichardo
authors.forename: Gil
authors.initials: G
authors.lastname: Yosipovitch
authors.forename: John
authors.initials: J
authors.lastname: Hancox
authors.forename: Omar P
authors.initials: OP
authors.lastname: Sangueza
mesh_terms: D000287:Administration, Topical; D000368:Aged; D001365:Axilla / Q000473:pathology; D005260:Female; D006801:Humans; D010241:Parakeratosis / Q000188:drug therapy / Q000209:etiology / Q000473:pathology*; D014221:Triamcinolone / Q000008:administration & dosage / Q000627:therapeutic use
chemical_list: D014221:Triamcinolone