Clinicopathological significance of stromal myofibroblasts in invasive ductal carcinoma of the breast.

The purpose of this study was to investigate the distribution of CD34-positive fibroblasts and alpha-smooth muscle actin (alpha-SMA)-reactive myofibroblasts in the stroma of benign and malignant breast lesions and, secondly, to determine whether the presence of stromal myofibroblasts is associated with some of the clinicopathological characteristics of patients with invasive ductal carcinoma. The presence of stromal CD34-positive fibroblasts and myofibroblasts was investigated (as defined immunohistochemically) in 8 normal breast tissue samples, 58 invasive ductal carcinomas, 9 ductal carcinomas in situ and 16 specimens with benign lesions of the breast (fibroadenomas, ductal hyperplasias). We further studied the correlations between the presence of stromal myofibroblasts with 7 clinicopathological parameters in 58 invasive ductal carcinomas. The results indicated that the stroma of normal breast tissues contained CD34-positive fibroblasts. All benign breast lesions exhibited stromal CD34-positive fibroblasts. In contrast, the stroma of ductal carcinomas showed a complete loss of CD34-positive fibroblasts. alpha-SMA expression in stromal fibroblasts (myofibroblasts) was not detected in normal tissue samples or benign lesions except in 1 case of fibroadenoma, whereas positive myofibroblasts were found in 44.4% of ductal carcinomas in situ and 56.9% of invasive breast carcinomas. Comparison of clinicopathological parameters between invasive ductal carcinomas with and without stromal myofibroblasts revealed significant differences in lymph node metastasis, high histological grade and high microvessel density. These results suggest that CD34 loss and the presence of myofibroblasts favor the diagnosis of breast carcinoma. In invasive ductal carcinoma, the presence of stromal myofibroblasts correlated significantly with pathological parameters associated with a poor prognosis. Copyright 2004 S. Karger AG, Basel.