Breast Cancer Metastasis to the Gastrointestinal Tract With Unusual Endoscopic and Histologic Presentations.

The gastrointestinal (GI) tract is an infrequent site of breast cancer metastasis, but it often poses a diagnostic challenge when it occurs. The symptoms of GI metastases are often nonspecific, and the endoscopic manifestations are variable, requiring tissue biopsies for histologic examination. We report 2 cases of breast cancer metastasizing to the GI tract: a case of human epidermal growth factor receptor 2-positive invasive ductal carcinoma that metastasized to the stomach, a rare location for this histologic subtype, and another case of invasive lobular cell carcinoma that metastasized to the colon with unusual findings of mucosal pallor and edema on colonoscopy.