Atypical junctional melanocytic proliferations in benign lichenoid keratosis

Hum Pathol. 2003 Jul;34(7):706-9. doi: 10.1016/s0046-8177(03)00234-x.

Abstract

Melanocytic lesions with lichenoid regression may mimic a benign lichenoid keratosis (BLK) histologically. A total of 336 BLKs were reviewed and deeper sections obtained to determine the frequency of this phenomenon. Two cases (0.6%) showed at least 1 melanocytic nest or junctional multinucleated melanocyte (starburst melanocyte) on deeper sections confirmed by MART-1 immunostaining. Both of these cases demonstrated solar elastosis, and 1 case had an effaced rete ridge pattern. Not included in the histological study are 5 additional cases in which the initial slide showed only lichenoid dermatitis, but deeper sections obtained before to the initial sign-out revealed a melanocytic proliferation. These 5 cases would have been signed out as "consistent with BLK" if deeper sections had not been obtained. Fluorescent in situ hybridization (FISH) was performed on 3 cases; in each case, the melanocytes demonstrated a loss of chromosome 9p21 DNA copy number. The finding of nests of genetically altered melanocytes on severely sun-damaged skin strongly suggests that these cases represent lichenoid regression of melanoma in situ. Pathologists should approach a diagnosis of BLK cautiously in the setting of severely sun-damaged skin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Antigens, Neoplasm / metabolism
  • Carcinoma in Situ / genetics
  • Carcinoma in Situ / metabolism
  • Carcinoma in Situ / pathology*
  • Chromosomes, Human, Pair 9
  • DNA / analysis
  • Diagnosis, Differential
  • Gene Dosage
  • Giant Cells / pathology
  • Humans
  • Hyperplasia / pathology
  • In Situ Hybridization, Fluorescence
  • Lichen Planus / genetics
  • Lichen Planus / metabolism
  • Lichen Planus / pathology*
  • MART-1 Antigen
  • Melanocytes / metabolism
  • Melanocytes / pathology*
  • Melanosis / metabolism
  • Melanosis / pathology*
  • Middle Aged
  • Neoplasm Proteins / metabolism
  • Precancerous Conditions / genetics
  • Precancerous Conditions / metabolism
  • Precancerous Conditions / pathology
  • Skin Neoplasms / genetics
  • Skin Neoplasms / metabolism
  • Skin Neoplasms / pathology*
  • Sunlight / adverse effects

Substances

  • Antigens, Neoplasm
  • MART-1 Antigen
  • MLANA protein, human
  • Neoplasm Proteins
  • DNA