title: Persistent melanocytic nevi: a review and analysis of 205 cases.
abstract: BACKGROUND
  Melanocytic nevi can recur or persist if not completely excised and are capable of mimicking malignant melanoma, both clinically and histologically.
  
  
  OBJECTIVE
  To characterize the impact of anatomic site, biopsy method, size, margin involvement and type of original melanocytic nevus on recurrence/persistence of melanocytic nevi. Secondarily, we sought to determine if the original type of melanocytic nevus could be determined solely from microscopic examination of the recurrent/persistent nevus.
  
  
  METHODS
  One hundred and eighty-five patients with 205 persistent nevi were identified. Of these, 108 cases had original biopsy specimens available for review. Location, original biopsy size, biopsy method, margins and interval to recurrence were recorded for each. A group of 232 non-persistent nevi was established as a control population.
  
  
  RESULTS
  There was a female predominance in persistent nevi with the back being the most common site for persistence. Dysplastic melanocytic nevi were the most likely to persist. Accurate determination of the original type of melanocytic nevus from microscopic examination of the persistent nevus was possible in only 67% of the cases.
  
  
  CONCLUSIONS
  Clinicians should take larger and deeper biopsies of clinically dysplastic and conventional melanocytic nevi on the back to prevent recurrences. Grading atypia of the persistent melanocytic nevi is unreliable.
authors.affiliation: Temple University School of Medicine, Philadelphia, PA, USA.
authors.forename: Lacy L
authors.initials: LL
authors.lastname: Sommer
authors.forename: Sara M
authors.initials: SM
authors.lastname: Barcia
authors.forename: Loren E
authors.initials: LE
authors.lastname: Clarke
authors.forename: Klaus F
authors.initials: KF
authors.lastname: Helm
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy / Q000379:methods; D002648:Child; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008545:Melanoma / Q000473:pathology; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology; D009508:Nevus, Pigmented / Q000473:pathology* / Q000601:surgery*; D012878:Skin Neoplasms / Q000473:pathology* / Q000601:surgery*; D055815:Young Adult