METHODS IN PATHOLOGY - SECRETORY CARCINOMA OF THE BREAST - LIGHT-MICROSCOPIC, IMMUNOHISTOCHEMICAL AND FLOW CYTOMETRIC STUDY

We studied five cases of secretory carcinoma of the breast (SC) by lig ht microscopy, by immunohistochemistry, and by flow cytometry. Four ca ses were retrieved from the series of 7038 cases of breast carcinoma s een in our department during the 20-yr period of 1973 to 1992; one cas e was seen recently. Histologically, different growth patterns in SC w ere observed; the most characteristic feature was prominent intra- and extracellular secretion. Immunohistochemically, all tumors showed str ong positive reaction for alpha-lactalbumin and S-100 protein, whereas the reactions to carcinoembryonic antigen and gross cystic disease fl uid protein were variable. By flow cytometry, four tumors were examine d (three of them were diploid and one near diploid), and they all show ed low S-phase fraction. Immunohistochemical findings in SC were compa red to a group of 13 cases of nonsecretory carcinoma that all showed a n appreciable degree of secretion or morphological similarities to SC. In a single case of cystic hypersecretory carcinoma an unequivocal po sitive reaction for alpha-lactalbumin was demonstrated; S- 100 positiv e reaction was seen in two cases. It was concluded that in an appropri ate morphological setting, positive reaction for alpha-lactalbumin is an essential feature in diagnosing SC. S-100 protein positivity and di ploid flow cytometric pattern are also characteristics of SC.