OBJECTIVETo evaluate the immunophenotype conversion of fibroblasts and its clinical significance in the process of breast tumor stromal remodeling.

METHODSCD34, FAP-α, p63 and a-SMA were detected by immunohistochemistry in 273 breast biopsies, including 60 normal breast tissues, 46 atypical ductal hyperplasia (ADH), 60 ductal carcinoma in situ (DCIS), 47 DCIS microinvasive carcinoma (DCIS-MI) and 60 invasive ductal carcinoma (IDC).

RESULTSThe positive expression rates of CD34, FAP-α and α-SMA in the stromal fibroblasts of normal breast tissues were 93.3%, 6.7% and 18.3%, respectively. Those in the stromal fibroblasts of ADH tissues were 95.7%, 4.3% and 10.9%, respectively. Those in the stromal fibroblasts of DCIS tissues were 95.0%, 8.3% and 15.0%, respectively. Those in the IDC tissues were 35.0%, 85.0% and 93.3%, respectively. The expressions of CD34, α-SMA and FAP-α in the stromal fibroblasts of normal, ASH and DCIS breast tissues did not show significant differences (χ(2) = 1.142, P = 0.896). The main immunophenotype of stromal fibroblasts in the tumor-host interface at the invasive front of ADH and DCIS lesions was CD34(+)α-SMA(+)FAP-α(+). There were statistically significant differences in the expression of CD34, α-SMA and FAP-α between IDC and ADH, DCIS and normal breast tissues (χ(2) = 8.351, P < 0.001). The immunophenotype of stromal fibroblasts in the IDC and DCIS-MI breast tissues was CD34(-) α-SMA(+) FAP-α(+).

CONCLUSIONSImmunophenotype conversion from CD34(+) α-SMA(-) FAP-α(-) to CD34(-) α-SMA(+)FAP-α(+) may be a sensitive indicator to judge whether DCIS has microinvasion. Detection of the immunophenotype conversion of stromal fibroblasts may be helpful to determine the presence of microinvasion, and to improve the diagnostic accuracy rate of DCIS.