Immunohistochemical detection of alphalactalbumin in breast lesions.

Alphalactalbumin was investigated in breast cells using the immunoperoxidase technique with a specific anti-alphalactalbumin serum. In 50 benign tumors alphalactalbumin immunoreactivity was demonstrated in the epithelium of fibroadenomas and in fibrocystic disease showing apocrine metaplasia. Alphalactalbumin immunoreactivity, investigated in 124 breast cancers, was present in all cells of lobular tumors but in only 76% of other cancers where the pattern was heterogeneous. Perineoplastic mammary tissue of normal appearance was not labeled with the anti-alphalactalbumin antiserum except where lobular hyperplasia was present. The presence of alphalactalbumin-type immunoreactivity was not correlated with the histopathological staging of Bloom and Richardson, nor with menopausal status. The incidence of positivity was 90% when estrogen and progesterone receptors were present in the tumor. The demonstration of alphalactalbumin using immunoperoxidase could be used to complement the histological classification of breast cancers.