title: Stromal CD10 expression in mammary fibroadenomas and phyllodes tumours.
abstract: OBJECTIVE
  CD10 (CALLA) has recently been reported to be expressed in spindle cell neoplasia, and has been used to differentiate endometrial stromal sarcoma from leiomyoma and leiomyosarcoma. In the breast, myoepithelial cells express CD10, but there are few studies of the expression of CD10 in mammary fibroepithelial lesions.
  
  
  METHODS
  Stromal CD10 expression was studied in 181 mammary phyllodes tumours (102 benign, 51 borderline malignant, and 28 frankly malignant) and 33 fibroadenomas using immunohistochemistry, to evaluate whether differences in expression correlated with the degree of malignancy.
  
  
  RESULTS
  There was a progressive increase in the patients' age and tumour size, from fibroadenoma to phyllodes tumours with an increasing degree of malignancy (p < 0.001). Stromal CD10 expression was positive in one of 33 fibroadenomas, six of 102 benign phyllodes tumours, 16 of 51 borderline malignant phyllodes tumours, and 14 of 28 frankly malignant phyllodes tumours. The difference was significant (p < 0.001) and an increasing trend was established. Strong staining was seen in subepithelial areas with higher stromal cellularity and activity. Stromal CD10 expression had a high specificity (95%) for differentiating between benign lesions (fibroadenomas and benign phyllodes tumours) and malignant (borderline and frankly malignant) phyllodes tumours.
  
  
  CONCLUSIONS
  CD10 may be a useful adjunct in assessing malignancy in mammary fibroepithelial lesions.
authors.affiliation: Department of Anatomical and Cellular Pathology, Prince of Wales Hospital, Ngan Shing Street, Shatin, NT, HKSAR, China. garytse@cuhk.edu.hk
authors.forename: G M K
authors.initials: GM
authors.lastname: Tse
authors.forename: A K H
authors.initials: AK
authors.lastname: Tsang
authors.forename: T C
authors.initials: TC
authors.lastname: Putti
authors.forename: R A
authors.initials: RA
authors.lastname: Scolyer
authors.forename: P C W
authors.initials: PC
authors.lastname: Lui
authors.forename: B K B
authors.initials: BK
authors.lastname: Law
authors.forename: R Z
authors.initials: RZ
authors.lastname: Karim
authors.forename: C S
authors.initials: CS
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000276:immunology* / Q000473:pathology; D005260:Female; D018226:Fibroadenoma / Q000276:immunology* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008875:Middle Aged; D015260:Neprilysin / Q000276:immunology*; D003557:Phyllodes Tumor / Q000276:immunology* / Q000473:pathology; D017154:Stromal Cells / Q000276:immunology*
chemical_list: D015260:Neprilysin