Metastatic breast cancer to colon: An unusual site of metastasis with a review of literature

Abstract

Gastrointestinal (GI) metastasis is very rare in patients with breast cancer (BC). This study reports a case with colon carcinoma metastasis originated from breast cancer in Western Iran. A 37-yearold female was diagnosed with infiltrating ductal carcinoma. Immunohistochemistry (IHC) results showed positive estrogen receptor, progesterone receptor, HER2 scored 2 out of 3, Ki-67 in 30% of tumor cells and P53. The patient was re-admitted two times with urinary and GI symptoms, positive tumor markers and thick colon wall. Samples from the colon were collected to test for metastasis. The pathologist reported metastatic breast ductal carcinoma spread to the colon. The IHC showed CK7, CK20, GCDFP15, ER and PR positivity. In conclusion, this IHC panel can be considered as the differential and diagnostic markers for malignant GI lesion originated from breast cancer.