title: Pseudoangiomatous stromal hyperplasia and breast cancer risk.
abstract: BACKGROUND
  Pseudoangiomatous stromal hyperplasia (PASH) is a benign localized fibrotic lesion in which clusters of spindle cells form cleftlike spaces, resembling ectatic vessels. Its relationship to breast cancer risk has not been characterized.
  
  
  METHODS
  Histological presence of PASH was evaluated by review of archival slides in a single institution cohort of women who underwent benign excisional breast biopsy from 1967 to 1991. Relative risks for subsequent breast cancer were estimated using standardized incidence ratios (SIR), comparing the observed number of cancers with those expected based on Iowa SEER data (mean follow-up 18.5 years).
  
  
  RESULTS
  PASH was identified in 579 of 9065 biopsies (6.4%). Women with PASH were younger, more likely to have a palpable mass as indication for biopsy, and had less lobular involution compared with those without PASH (all P < 0.001), while they did not differ by family history of breast cancer or degree of epithelial proliferation. Breast cancers occurred in 34 women with PASH (5.9%) and 789 without (8.8%). Women with PASH had lower risk of breast cancer (SIR 1.03, 95% confidence interval [95% CI] 0.71-1.44) than those without PASH (SIR 1.54, 95% CI 1.43-1.65), P = 0.01. Lower levels of breast cancer risk for the PASH group persisted in analyses stratified by age, family history, epithelial proliferation, and involution. The cancers in the PASH group occurred predominantly in the ipsilateral breast more than 5 years after biopsy.
  
  
  CONCLUSIONS
  Despite clinical concern generated by palpable density often associated with PASH, this relatively uncommon histological finding does not connote increased risk of subsequent breast cancer.
authors.affiliation: Department of Surgery, Mayo Clinic, Rochester, MN, USA. degnim.amy@mayo.edu
authors.forename: Amy C
authors.initials: AC
authors.lastname: Degnim
authors.forename: Marlene H
authors.initials: MH
authors.lastname: Frost
authors.forename: Derek C
authors.initials: DC
authors.lastname: Radisky
authors.forename: Stephanie S
authors.initials: SS
authors.lastname: Anderson
authors.forename: Robert A
authors.initials: RA
authors.lastname: Vierkant
authors.forename: Judy C
authors.initials: JC
authors.lastname: Boughey
authors.forename: V Shane
authors.initials: VS
authors.lastname: Pankratz
authors.forename: Karthik
authors.initials: K
authors.lastname: Ghosh
authors.forename: Lynn C
authors.initials: LC
authors.lastname: Hartmann
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Visscher
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000798:Angiomatosis / Q000150:complications* / Q000473:pathology; D001940:Breast / Q000473:pathology*; D001943:Breast Neoplasms / Q000209:etiology* / Q000473:pathology; D018270:Carcinoma, Ductal, Breast / Q000150:complications / Q000473:pathology; D018275:Carcinoma, Lobular / Q000150:complications / Q000473:pathology; D005260:Female; D018226:Fibroadenoma / Q000150:complications / Q000473:pathology; D005500:Follow-Up Studies; D006801:Humans; D006965:Hyperplasia / Q000150:complications* / Q000473:pathology; D008875:Middle Aged; D012307:Risk Factors; D017154:Stromal Cells / Q000473:pathology*; D015996:Survival Rate; D016896:Treatment Outcome; D055815:Young Adult