RESUMEN
Objective To study the expression and clinical significance of CD34 and smooth muscle actin (SMA) in stroma of breast tissues and lesions. Methods Seventy cases of breast tissues and lesions, including 20 fibroadenomas, 10 sclerosing adnoses, 30 invasive ductal carcinomas and 10 invasive lobular carcinomas were investigated, and 10 normal breast tissues were served as controls. Immunohistochemical staining was applied to compare the distribution of CD34+ fibrocytes and SMA-reactive myofibroblasts. Results The stroma of normal breast tissue contained CD34+ fibrocytes, whereas SMA-reactive myofibroblasts were absent (100% for both). All benign breast lesions exhibited astromal CD34+ fibrobytes, and fibroadenomas showed SMA-reactive myofibroblasts as well. In invasive ductal and lobular carcinoma the stroma was devoid of CD34+ fibrocytes, but a varying number of stromal SMA-reactive myofibroblasts were detectable (100%). Conclusion In breast carcer, immunohistochemical staining used in detecting expressions of CD34 and SMA is helpful in distinguishing benign lesions from malignancies.