Among a group of 392 patients with carcinoma of the breast treated at the Cincinnati General Hospital since 1950 certain clinicopathological patterns have shown a more favorable prognosis than the group as a whole. Three such patterns have been examined in some detail, namely colloid carcinoma, medullary carcinoma with lymphoid stroma, and intraductal carcinoma. Clinicians have repeatedly pointed out that the outlook in certain types of breast carcinoma may be more favorable than might be expected,2but a note of caution has usually been added in predicting the outcome of any individual case. Pathologists have traditionally classified breast cancers into various descriptive categories with the implication that the morphologic pattern might in certain instances offer valuable information concerning prognosis.7Most striking of such correlations between morphology and prognosis has been the type of cancer designated as medullary carcinoma with lymphoid stroma, which was first described by Moore and