Phyllodes tumor: a clinicopathologic and immunohistochemical study of 30 cases.
BACKGROUND
Phyllodes tumors (PTs) of the breast are biphasic neoplasms composed of epithelium and a spindle-cell stroma. Currently, PTs are classified as benign, borderline, or malignant based on histopathologic features. However, histologic classification does not always predict outcome. Objective.-To determine the prognostic value of a variety of clinicopathologic features and immunoreactivities in PTs.


METHODS
Sixteen benign, 8 borderline, and 6 malignant PTs with follow-up were examined for reactivity across a panel of immunohistochemical stains, including c-Kit, endothelin 1, p16, p21, p53, and Ki-67. Clinicopathologic features, including stromal cellularity, mitotic rate, and margin status, were also assessed. Tumor variables were compared among tumor subgroups and between tumors that did and did not recur.


RESULTS
Of the 30 PTs, 4 recurred (1 benign, 2 borderline, 1 malignant). One patient with a malignant tumor died of metastatic disease 34 months after initial diagnosis. The overall positive rate of c-Kit immunoreactivity was 13% in benign, 63% in borderline, and 67% in malignant PTs. Endothelin 1 epithelial cytoplasmic staining was seen in 100% of benign, 50% of borderline, and 17% of malignant PTs. Additionally, p16, p21, p53, and Ki-67 were differentially expressed among benign, borderline, and malignant tumors. Positive surgical resection margins was the only variable that significantly predicted recurrent disease (P = .02).


CONCLUSIONS
Stromal c-Kit positivity and epithelial endothelin 1 negativity are more often associated with malignant PTs; however, only positive margin status is significantly associated with tumor behavior.
Esposito
Nicole Nicosia
NN
Department of Pathology, University of Pittsburgh, Pittsburgh, Pa 15213, USA. espositonc@upmc.edu
Mohan
Deepak
D
Brufsky
Adam
A
Lin
Yan
Y
Kapali
Malathy
M
Dabbs
David J
DJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology* / Q000601:surgery; D018450:Disease Progression; D019332:Endothelin-1 / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D019394:Ki-67 Antigen / Q000378:metabolism; D008408:Mastectomy; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D003557:Phyllodes Tumor / Q000378:metabolism* / Q000473:pathology* / Q000601:surgery; D011379:Prognosis; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D013194:Staining and Labeling; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D014408:Biomarkers, Tumor; D019332:Endothelin-1; D019394:Ki-67 Antigen; D016159:Tumor Suppressor Protein p53; D019009:Proto-Oncogene Proteins c-kit