Characterisation of adenoid cystic carcinoma of the breast by immunohistology.

An adenoid cystic carcinoma of the breast in a 78 year old woman was analysed immunohistologically for the production of type IV collagen, the expression of vimentin, epithelial membrane antigen (EMA) and steroid receptors, and the proliferative activity of the tumour cells. The data were compared with those obtained in eight adenoid cystic carcinomas of salivary glands and in ductal carcinomas of the breast with a cribriform growth pattern. The patients' ages were as follows: 45-80 years (mean 63.2) for the salivary gland carcinomas; 37-69 years (mean 50.6) for the ductal breast carcinomas. In contrast to the cribriform spaces of ductal carcinomas, the pseudocysts in adenoid cystic carcinomas were lined by type IV collagen. The opposite pattern was observed for EMA. Like the myoepithelium of normal breast, the myoepithelium-like cells of adenoid cystic carcinoma stained positive for vimentin while the ductular epithelium-like ones did not. All adenoid cystic carcinomas, including that of the breast, were negative for the oestrogen and progesterone receptors, unlike the ductal carcinomas. Proliferative activity of the adenoid cystic carcinoma of the breast was relatively low. These data broaden the range of antibodies suitable for differential diagnosis of both tumour types. They may explain the differences in prognosis, and they explain why hormonal treatment or radiotherapy of adenoid cystic carcinoma of the breast are often ineffectual.