title: Microglandular adenosis or microglandular adenoma? A molecular genetic analysis of a case associated with atypia and invasive carcinoma.
abstract: OBJECTIVE
  Microglandular adenosis (MGA) is a rare breast lesion, which has long been considered to be hyperplastic. However, atypical forms of MGA (AMGA) and invasive carcinomas arising in the background of MGA are recorded. Recent studies have suggested that MGA may be a non-obligate precursor of invasive carcinomas that are negative for hormone receptors and lack HER-2 overexpression (triple-negative phenotype). The aim of this study was to determine whether MGA is clonal and whether it harbours chromosomal aberrations similar to those found in matched invasive ductal carcinoma of no special type (IDC-NST).
  
  
  RESULTS
  We report on a case comprising MGA, AMGA and a high-grade IDC-NST. The three components were separately microdissected and subjected to genetic analysis with high-resolution microarray comparative genomic hybridisation. Identical genetic changes were detected in all components with subsequent acquisition of additional genetic aberrations in the invasive component, suggesting that MGA was the substrate for the development of the invasive carcinoma. Immunohistochemistry revealed concordant profiles across all components, characterized by triple-negative phenotype and variable positivity for basal markers.
  
  
  CONCLUSIONS
  Similar to adenomas, MGA is, at least in some cases, a clonal lesion and may be a non-obligate precursor of a subgroup of high-grade triple-negative and basal-like breast carcinomas.
authors.affiliation: The Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, UK.
authors.forename: Felipe C
authors.initials: FC
authors.lastname: Geyer
authors.forename: Yael B
authors.initials: YB
authors.lastname: Kushner
authors.forename: Maryou B
authors.initials: MB
authors.lastname: Lambros
authors.forename: Rachael
authors.initials: R
authors.lastname: Natrajan
authors.forename: Alan
authors.initials: A
authors.lastname: Mackay
authors.forename: Narinder
authors.initials: N
authors.lastname: Tamber
authors.forename: Kerry
authors.initials: K
authors.lastname: Fenwick
authors.forename: Dave
authors.initials: D
authors.lastname: Purnell
authors.forename: Alan
authors.initials: A
authors.lastname: Ashworth
authors.forename: Rosemary A
authors.initials: RA
authors.lastname: Walker
authors.forename: Jorge S
authors.initials: JS
authors.lastname: Reis-Filho
mesh_terms: D000236:Adenoma / Q000175:diagnosis* / Q000235:genetics*; D000368:Aged; D014408:Biomarkers, Tumor / Q000235:genetics; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000235:genetics*; D018270:Carcinoma, Ductal, Breast / Q000235:genetics*; D003937:Diagnosis, Differential; D005260:Female; D005348:Fibrocystic Breast Disease / Q000175:diagnosis* / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D020411:Oligonucleotide Array Sequence Analysis
chemical_list: D014408:Biomarkers, Tumor