Synchronous Gastric Metastasis From Sigmoid Colon Cancer: A Case Report

Colorectal cancer is the third most common cancer worldwide, and as such is a significant global health concern. Distant metastases of colorectal cancer to the lung, liver, and bone are well documented, while gastrointestinal tract (GIT) metastases are very rare. Herein, we report a case of gastric metastasis from sigmoid colon cancer. A 78-year-old male was diagnosed with both gastric and colorectal cancer, which occurred synchronously. The presence of two primary cancers was diagnosed, and radical subtotal gastrectomy and anterior resection were performed simultaneously. The postoperative pathology report showed a moderately differentiated adenocarcinoma in the sigmoid colon and stomach. Immunohistochemical (IHC) analysis revealed that the resected gastric specimens showed tumor cells that were positive for both cytokeratin 20 (CK20) and caudal-type homeobox gene 2 (CDX2) and negative for CK7. This confirmed that the gastric lesion was a metastasis from colorectal cancer. Clinicians should be aware of the potential presence of metastatic gastric cancer, whether synchronous or metachronous, in other solid organ malignancies.