Morphologic And Immunophenotypic Characteristics Of Phyllodes Tumors Of The Breast

Objective To investigate the morphologic and immunophenotypic characteristics of phyllodes tumors(PTs) of the breast and explore the differential diagnosis criteria. Methods 48 cases of PTs of the breast were observed with stains of hematoxylin eosin and studied by immunohistochemical method. 5 cases of normal breast, 5 cases of adenosis and 10 cases of fibroadenoma(FA) were randomly selected as the control at the same period. Results (1) Among the 48 cases of PTs, 24 cases showed glandular epithelium apocrine, 20 cases stromal overgrowth, 10 cases stromal cells growing as cuffs, 10 cases stromal myxoid changes, 4 cases pseudoangioma stromal hyperplasia, 3 cases vascellum overgrowth as angiomatous changes, 8 cases vortex or palisade arrangement. (2)The stromal staining of CD34 was moderate-strong positive in all benign and 10 of 16 borderline PTs, but negative in all malignant PTs, there was a statistical difference of the expression of CD34 among benign, borderline and malignant PTs(P<0.01). The stromal expression of SMA was moderate-strong positive in 16 of 22 benign, 12 of 16 borderline and 5 of 10 malignant PTs, the difference was not significant(p>0.05). Stromal CD10 was found in 4 of 22 benign, 14 of 16 borderline and 8 of 10 malignant PTs, there was a statistical difference of the expression of CD10 among benign, borderline and malignant PTs(P<0.01). The stromal expression of CD117 was positive in 2 cases(1 benign, 1 malignant) of 48 PTs. Of 48 cases of PTs, the expression rates of P53 and Ki-67 in benign, borderline and malignant PTs were respectively 7%, 20%, 30% and 14%, 28%, 63%, there was statistical difference of the expression of Ki-67 among benign, borderline and malignant PTs (P<0.01), but the difference of P53 was not significant. (3) Intralobular fibroblasts are immunoreactive for CD34. (4) The predominant non-epithelial elements are CD34-positive cells in adenosis, fibroadenoma and benign PTs. (5) The expression of CD34 was loss in borderline PTs. (6) The expression of loss of CD34 was general in manignant PTs. (7) The stromal expression of CD10 was frequently positive in borderline and malignant PTs. (8) The moderate-strong staining of P53 and Ki-67 was found only in borderline and malignant PTs. Conclusions (1) There was a significant difference in the expression of immunophenotype in benign, borderline and malignant PTs. (2) CD34 and CD10 may be useful in assisting in the differential diagnosis of benign, borderline and malignant PTs.