Alveolar variant of invasive lobular carcinoma of the breast. A tumor rich in estrogen receptors.

During a study of the correlation between the histologic types of breast carcinoma and their hormone receptor contents, eight cases of the alveolar variant of invasive lobular carcinoma were identified, and all had estrogen receptor protein concentrations higher than 400 fmol/mg cytosol protein. Four more cases of the same variant were later prospectively diagnosed and their high estrogen receptor concentrations correctly predicted. All 12 tumors occurred in postmenopausal women. Most (92%) presented in Stage I or II of the disease. None of the patients died of the tumors during the short period of follow-up (median two years). It is concluded that the alveolar variant of lobular carcinoma of the breast is a tumor with consistently high estrogen receptor concentration and probably a low-grade malignancy. It is also suggested that the tumor may be the lobular equivalent of the ductal infiltrating Comedo carcinoma.