Figure 1

Atypical lobular hyperplasia and lobular carcinoma in situ, classic type, and variants. (a) Atypical lobular hyperplasia with neoplastic cells replacing normal glandular epithelium in acinar units effacing the lumens. The acini remain small, nondistended, and the borders of acinar units remain indistinct (H&E × 200). (b) Lobular carcinoma in situ, classic type, consists of a uniform population of discohesive cells with bland nuclei and intracytoplasmic mucin vacuoles (H&E × 200). (c) Lobular carcinoma in situ with necrosis, with ductules markedly distended by cells with classic morphologic features of lobular neoplasia and displaying central luminal necrosis (H&E × 200). (d) Lobular carcinoma in situ, pleomorphic type, with large discohesive cells with eccentrically placed large nuclei (>3 × the size of lymphocyte), moderate pleomorphism, and distinct small nucleoli (H&E × 400).