title: Significant histologic features differentiating cellular fibroadenoma from phyllodes tumor on core needle biopsy specimens.
abstract: OBJECTIVE
  Cellular fibroepithelial lesions (CFELs) are a heterogeneous group of tumors encompassing cellular fibroadenoma (CFA) and phyllodes tumor (PT). Distinction between the two is challenging on core needle biopsy (CNB) specimens. The objective of this study was to evaluate histologic features that can help distinguish PT from CFA on CNB specimens.
  
  
  METHODS
  Records of all patients diagnosed with CFELs on CNB specimens with follow-up excision between January 2002 and December 2012 were retrieved. Histopathologic stromal features were evaluated on CNB specimens, including mitoses per 10 high-power fields (hpf), overgrowth, increased cellularity, fragmentation, adipose tissue infiltration, heterogeneity, subepithelial condensation, and nuclear pleomorphism.
  
  
  RESULTS
  Twenty-seven (42.2%) of 64 were diagnosed as PT (24 benign PTs and three borderline PTs) and 37 (57.8%) as CFA on excision. All features except for increased stromal cellularity were statistically significant. The average number of histologic features seen in PT and CFA was 3.9 and 1.4, respectively (odds ratio [OR], 7.27; 95% confidence interval [CI], 2.44-21.69; P = .0004). The average number of mitoses per 10 hpf was 3.0 for PT compared with 0.8 for CFA (OR, 2.14; 95% CI, 1.18-3.86; P = .01).
  
  
  CONCLUSIONS
  The presence of mitoses (three or more) and/or total histologic features of three or more on CNB specimens were the most helpful features in predicting PT on excision.
authors.affiliation: From the Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN;
authors.forename: Saba
authors.initials: S
authors.lastname: Yasir
authors.affiliation: Department of Pathology and Laboratory Medicine, Loyola University, Chicago, IL;
authors.forename: Roberto
authors.initials: R
authors.lastname: Gamez
authors.affiliation: Department of Health Sciences Research, Mayo Clinic, Rochester, MN; and.
authors.forename: Sarah
authors.initials: S
authors.lastname: Jenkins
authors.affiliation: From the Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN;
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Visscher
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic, Jacksonville, FL. Nassar.aziza@mayo.edu.
authors.forename: Aziza
authors.initials: A
authors.lastname: Nassar
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D062005:Biopsy, Large-Core Needle; D001943:Breast Neoplasms / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D018226:Fibroadenoma / Q000473:pathology*; D006801:Humans; D008875:Middle Aged; D003557:Phyllodes Tumor / Q000473:pathology*; D017154:Stromal Cells / Q000473:pathology; D055815:Young Adult
keywords: Biopsy specimens; Fibroadenoma; Fibroepithelial lesions; Needle cores; Phyllodes tumor