Gastrointestinal tract metastasis with subsequent intussusception and obstruction from an invasive lobular breast cancer: a case report.

Breast cancer is the commonest cancer in female population with lobular subtype comprising about 10% of all breast cancers. Breast cancer metastasis occurs in 0.3-18% of patients, with lobular cancer again being the most common subtype. We present an 85-year-old female with previous history of right breast lobular carcinoma in situ (LCIS), who was diagnosed to have lobular carcinoma of breast metastasising to stomach after 10 years of initial diagnosis. After 2 years, the patient was found to have metastasis to the terminal ileum and caecum causing intussusception, which led to obstruction. The patient's primary LCIS was estrogen receptor (ER) positive, progesterone receptor (PR) negative and Her2neu negative, which correlated with both the gastric and ileocecal lesions. The gastric and ileocecal masses both were positive for CK7 and GATA 3 and negative for E-cadherin and CD20. Detailed morphological and immunohistochemical analysis can differentiate primary lobular cancer of the gastrointestinal tract from metastatic cancer.