CD34+ fibrocytes in tubular carcinomas and radial scars of the breast.

The present study was undertaken to analyze whether and to what extent CD34+ fibrocytes and alpha-smooth muscle actin (alpha-SMA)-positive myofibroblasts occur in the stroma of radial scars and tubular carcinoma of the breast. We investigated a total of 24 radial scars obtained from 23 females and a total of 43 tubular carcinomas. All tubular carcinomas showed a virtually complete loss of CD34+ fibrocytes paralleled by a gain of alpha-SMA-positive myofibroblasts. The peripheral parts of radial scars harbored CD34+ fibrocytes comparable to normal breast tissue. In 23 of 24 radial scars, the central core was characterized by a loss of CD34+ fibrocytes accompanied by the presence of alpha-SMA-positive myofibroblasts in six cases, a pattern that up to now has only been described in malignant breast lesions. This finding underlines the close relationship between tubular carcinomas and radial scars. We conclude CD34- and alpha-SMA immunohistochemistry to be valuable adjunctive tools in distinguishing radial scars from tubular carcinomas. In the present study, the presence of CD34+ fibrocytes excluded malignancy. The absence of CD34+ fibrocytes paralleled by the presence of alpha-SMA myofibroblasts indicated malignancy in most cases, although it has to be carefully considered that in a minority of cases (6 of 24) the central core of radial scars may disclose this stromal composition.