What is invasive lobular carcinoma?

➢ Consists of infiltrating cells that are morphologically similar to the tumor cells seen in LCIS; ➢ two-thirds of the cases are associated with LCIS ➢ 10% to 15% of all breast carcinomas. ➢ The cells invade stroma individually and often are aligned in “single-file” ➢ Although most manifest as palpable masses or mammographic densities, a significant subgroup invade without producing a desmoplastic response; ➢ May be clinically occult and difficult to detect by imaging ➢ The pattern of metastasis of lobular carcinoma is unique among breast cancers, as they frequently spread to cerebrospinal fluid, serosal surfaces, gastrointestinal tract, ovary, uterus, and bone marrow. ➢ Almost all lobular carcinomas express hormone receptors, whereas HER2 overexpression is rare