Figure 1. Bifidobacteria relative abundance demonstrates a lasting decline after SARS-CoV-2 mRNA vaccination. [2100] Figure 1. Colonoscopy findings of diffuse edema and pallor of the (a) descending colon (b) sigmoid colon. (c) The infiltrating atypical cells in the lamina propria are strongly and diffusely positive for pancytokeratin confirming the diagnosis of metastatic mammary lobular carcinoma (103).

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.Patient 2: A 69-year-old woman with a history of triple-negative breast ILC with known metastatic disease to the bone, stomach, and liver presented to our hospital with 1 month of profuse diarrhea with greater than 10 nonbloody, loose stools