Colon Metastasis From Gastric Adenocarcinoma

Abstract

The colon is a common site of primary malignancy; however it is very rare metastatic localization. Here we describe a case of a signet ring cell carcinoma of the stomach metastasizing to the cecum and terminal ilium. Although colonoscopy finding was not very impressive, histopathology uncovers the diagnosis of clear cell adenocarcinoma of the colon and small intestine. 59 years- old male with history of Coronary artery disease who underwent percutaneous coronary intervention with stents in 2012. Few months later he developed hematemesis. EGD was performed which shows gastric ulcer. Biopsy revealed poorly differentiated clear cell adenocarcinoma Her 2 positive. Work up for metastasis was negative. It was staged as IIB. He underwent partial gastrectomy with Roux- en-Y Procedure. Subsequently, he received neo-adjuvant chemotherapy. Patient was then followed up with imaging and subsequent EGDs with no evidence of disease recurrence. In 2014 patient presented with melena. His CEA was elevated. Repeated EGD shows no evidence of recurrence. He also started to develop Melena. Colonoscopy was performed in Feb 2015 revealing hyper vascular area. Biopsy from the lesion showed poorly differentiated signet cell adenocarcima with similar histopathology and grading of previous gastric cancer. It was concluded that the malignancy is likely metastatic from gastric cancer. Patient underwent exploratory laparotomy with Right hemi colectomy. Two lesions were also noted in the terminal ilium that were resected. Histopathology confirms the diagnosis of signet cell adenocarcinoma in colon and small intestine. Patient underwent imaging for further staging which shown no evidence of other metastasis. He was then started on chemotherapy including Taxol and Herceptin. Metastases rarely involve the intestinal tract. As a matter of fact, gut metastases have been mostly described for specific tumors such as melanoma and contiguous Spreading of ovarian carcinoma. Gastric cancer spread to the colon is very rare, when it occur it carries a very poor prognosis and denotes likely poorly differentiated and aggressive type of cancer. Generally this unusual localization has been associated to Lauren's diffuse type histology and peritoneal dissemination. In our patient gross colonoscopy finding was not impressive, however pathology revealed the diagnosis. Clinicians should be aware that because of infiltrative nature of the disease, grossly it can appear as only mucosal color changes and only lesion biopsy can reveal the diagnosis of such rare, though aggressive metastasis. Nonetheless, gastric adenocarcinoma, especially if it is poorly differentiated or the signet ring cell type, should be considered as one of the common tumors that have the propensity for rare intestinal metastases.