Benign and malignant stellate breast lesions: structural differences in 5 microns sections and thick tissue slices.

Complex sclerosing lesions have presented a diagnostic problem since they were identified amongst benign breast lesions. Their differentiation from stellate carcinomas may cause serious difficulties for both radiologists and pathologists. In the present study the conventional and thick-slice appearances of 15 complex sclerosing lesions and 15 well differentiated and tubular carcinomas were compared, with the main emphasis on the stellate zone of the lesions. There was a marked morphological difference between the stellate extensions: the majority was formed by epithelial structures in complex sclerosing lesions as opposed to the composition of the extensions of the stellate carcinomas, where fibrovascular tissue dominates. Well differentiated carcinomas originating in complex sclerosing lesions showed an intermediate ratio of epithelial and fibrous stellate extensions. The structural differences may explain the radiomorphological differences of benign and malignant stellate breast lesions. We suggest these structural characteristics ought to be included in the pathomorphologic differential diagnostic features.