The cells are monomorphic with bland, round nuclei and occur in loosely cohesive clusters in ducts and lobules. Intracellular mucin vacuoles (signet ring cells) are common.
it does not form masses and is only rarely associated with calcifications. Therefore, the incidence of LCIS is almost unchanged in mammographically screened populations
Current treatment requires either close clinical and radiologic follow-up of both breasts or bilateral prophylactic mastectomy
Lobular carcinoma in situ. A monomorphic population of small, rounded, loosely cohesive cells fills and expands the acini of a lobule. The underlying lobular architecture can still be recognized.