title: Neuroendocrine cells associated with neuroendocrine carcinoma of the breast: nature and significance.
abstract: BACKGROUND
  The developmental mechanisms of breast neuroendocrine carcinoma (B-NEC) have not been sufficiently analysed and are not well understood.
  
  
  OBJECTIVE
  To investigate NE cells in the background tissues surrounding B-NECs.
  
  
  METHODS
  Three cases (four breasts) having many NE cells in the background tissues of multifocal B-NECs were identified at the University of Yamanashi Hospital and St Luke's International Hospital, Japan. These patients were, respectively, 28-, 31- and 38-year-old women with no familial history of NE tumour. The totally-resected breasts were serially studied by immunohistochemistry for specific NE markers (chromogranin A/synaptophysin) and the morphologies and/or localisation of NE cells were investigated.
  
  
  RESULTS
  Immunohistochemical examination showed extensively-distributed NE cells in the background mammary ducts/lobules of the NECs in all breasts. These NE cells were classifiable into three emerging patterns: isolated/scattered, clustered and circumferential. Their distributions were intermingled and were not clearly related to B-NEC foci. NE cells were morphologically polygonal, oval or columnar with sometimes eosinophilic and/or fine-granular cytoplasm and round-to-ovoid nuclei lacking atypia. Some cells were located between epithelial and myoepithelial cells. Apical snouts were occasionally observed in NE cells forming luminal structures.
  
  
  CONCLUSIONS
  Benign-appearing NE cells in the parenchyma of a breast with NEC could be regarded as hyperplastic from their emerging patterns and distribution; this NE cell hyperplasia may be associated with the histogenesis of B-NEC as a precancerous condition. These observations might raise questions about the treatment for B-NEC.
authors.affiliation: Department of Pathology, University of Yamanashi, Yamanashi, Japan. tomonori@yamanashi.ac.jp
authors.forename: Tomonori
authors.initials: T
authors.lastname: Kawasaki
authors.forename: Kunio
authors.initials: K
authors.lastname: Mochizuki
authors.forename: Hideko
authors.initials: H
authors.lastname: Yamauchi
authors.forename: Shingo
authors.initials: S
authors.lastname: Inoue
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kondo
authors.forename: Naoki
authors.initials: N
authors.lastname: Oishi
authors.forename: Tadao
authors.initials: T
authors.lastname: Nakazawa
authors.forename: Tetsu
authors.initials: T
authors.lastname: Yamane
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Koshimizu
authors.forename: Hiroko
authors.initials: H
authors.lastname: Tsunoda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yagata
authors.forename: Masayuki
authors.initials: M
authors.lastname: Inoue
authors.forename: Ayako
authors.initials: A
authors.lastname: Inoue
authors.forename: Takanori
authors.initials: T
authors.lastname: Maruyama
authors.forename: Hideki
authors.initials: H
authors.lastname: Fujii
authors.forename: Ryohei
authors.initials: R
authors.lastname: Katoh
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000032:analysis; D001943:Breast Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D018278:Carcinoma, Neuroendocrine / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D048430:Cell Shape; D053379:Chromogranin A / Q000032:analysis; D005260:Female; D006801:Humans; D006965:Hyperplasia; D007150:Immunohistochemistry; D055099:Neuroendocrine Cells / Q000737:chemistry / Q000473:pathology*; D011379:Prognosis; D016708:Synaptophysin; D033921:Vesicular Transport Proteins / Q000032:analysis
chemical_list: D014408:Biomarkers, Tumor; C506150:CHGA protein, human; D053379:Chromogranin A; C569014:SYP protein, human; D016708:Synaptophysin; D033921:Vesicular Transport Proteins