Pseudoangiomatous stromal hyperplasia and breast cancer risk.
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.
Degnim
Amy C
AC
Department of Surgery, Mayo Clinic, Rochester, MN, USA. degnim.amy@mayo.edu
Frost
Marlene H
MH
Radisky
Derek C
DC
Anderson
Stephanie S
SS
Vierkant
Robert A
RA
Boughey
Judy C
JC
Pankratz
V Shane
VS
Ghosh
Karthik
K
Hartmann
Lynn C
LC
Visscher
Daniel W
DW
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