title: Seborrheic keratosis with pseudorosettes and adamantinoid seborrheic keratosis: two new histopathologic variants.
abstract: OBJECTIVE
  Seborrheic keratoses are the most common benign cutaneous neoplasms in adult and middle-age patients. There are six distinctive histopathologic variants of seborrheic keratosis, namely, acanthotic or solid, reticulated or adenoid, hyperkeratotic or papillomatous, clonal or nested, irritated and inflamed.
  
  
  METHODS
  We report two additional histopathologic variants of seborrheic keratosis.
  
  
  RESULTS
  One lesion showed abundant intercellular mucin, closely resembling to adamantinoma, and therefore was named adamantinoid seborrheic keratosis. The other one exhibited a peculiar distribution of the basaloid keratinocytes, which were arranged radially around small central spaces, resulting in pseudorosette formation.
  
  
  CONCLUSIONS
  To our knowledge, these two histopathologic variants of seborrheic keratosis have been not previously described in the literature.
authors.affiliation: Department of Dermatology, Fundación Jiménez Díaz, Universidad Autónoma, Madrid, Spain. lrequena@fjd.es
authors.forename: Luis
authors.initials: L
authors.lastname: Requena
authors.forename: Heinz
authors.initials: H
authors.lastname: Kutzner
mesh_terms: D050398:Adamantinoma / Q000145:classification / Q000473:pathology*; D000368:Aged; D005260:Female; D006801:Humans; D015603:Keratinocytes / Q000473:pathology*; D017492:Keratosis, Seborrheic / Q000145:classification / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012878:Skin Neoplasms / Q000145:classification / Q000473:pathology*