title: The recurrent nevus phenomenon: a history of challenge, controversy, and discovery.
abstract: BACKGROUND
  The diagnosis of recurrent nevus poses a potential challenge to practicing pathologists. Although most recurrent nevi show uniform microscopic findings and pose no great diagnostic difficulty, a few cases exhibit some histopathologic features similar to, and in some cases indistinguishable from, melanoma. Historically, the term pseudomelanoma has been used in the literature to describe such recurrent nevi, although this label has the potential for confusion and is no longer the favored term for recurrent pigmented melanocytic nevi.
  
  
  OBJECTIVE
  To describe historical, histopathologic, and immunohistochemical features of recurrent pigmented melanocytic nevi and to review briefly the literature surrounding the mechanism of recurrence.
  
  
  METHODS
  Published peer-reviewed literature and the authors' personal experience.
  
  
  CONCLUSIONS
  Recognition of the histopathologic pattern of recurrent nevi leads the pathologist to the correct diagnosis in most cases; however, in particularly challenging specimens or in circumstances in which there is insufficient clinical history, immunohistochemical studies have proved helpful in distinguishing recurrent nevi from melanoma.
authors: Section of Dermatology, University of Chicago, Chicago, Illinois 60637, USA.
authors: John C
authors: JC
authors: Fox
authors: Jon A
authors: JA
authors: Reed
authors: Christopher R
authors: CR
authors: Shea
mesh_terms: D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D008545:Melanoma / Q000378:metabolism / Q000473:pathology*; D009506:Nevus / Q000378:metabolism / Q000473:pathology*; D012008:Recurrence; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology*