The contemporary perception of lobular carcinoma in situ (LCIS) as a risk factor for breast cancer, as opposed to being a direct precursor lesion, has evolved gradually over the past several decades. In 1941 Foote and Stewart (1) published their landmark study of LCIS, describing a relatively rare entity within the broad spectrum of breast pathologic processes characterized by an “alteration of lobular cytology.” The now wellestablished histologic features of LCIS were based on findings present in 14 of 300 cancerous mastectomy specimens (4.67%) from Memorial Hospital in New York City; in 2 cases (0.67%) this was described as “typical LCIS” fulfilling “strict” criteria; in another 2 the LCIS was scanty in amount; and in the remaining 10 cases, it was intermediate in extent. Foote and Stewart described this aberration of normal breast architecture as being notable for “the presence of a lobule or group of lobules in which . . . [t]he nuclei tend to be rather clear; they show no hyperchromatism. The cytoplasm is apt to be opaque, somewhat acidophilic, and occasionally vacuolated. The compact, orderly arrangement of the epithelium of the normal lobule gives place to a decided looseness, a loss of cohesion.” These pathologists also documented the tendency for this disturbance of the terminal duct-lobular units to be diffuse, and they furthermore ascertained its occult nature, reporting that “it is always a disease of multiple foci” and that “there is no way by which it can be recognized grossly” (1).

Numerous ...