AB133. SOH23ABS_112. Colonic carcinoma metastasized from signet-ring cell gastric cancer: a case report

Background: Gastric carcinoma accounts for 2.7% of all malignant neoplasms in Ireland. Colorectal metastases from the gastric primary are exceedingly rare. We report an unusual case of colonic metastasis of gastric carcinoma. An 84-year-old male presented with abdominal pain associated with constipation and tenderness in the lower abdomen. The patient was previously diagnosed as cT4aN1M1 with poorly differentiated adenocarcinoma of the stomach invading the pancreas. A restaging scan and oesophago-gastro-duodenoscopy (OGD) performed to the patient revealed a good response upon chemotherapy with 5-FU.

Methods: Abdominal computed tomography (CT) at admission showed a well-evolved circumferential structuring lesion of the proximal transverse colon with evidence of dilatation and perforation of the caecum. Exploratory laparotomy revealed an obstructing mass in the transverse colon with cecal perforation and no palpable liver mass. We did right hemicolectomy and ileostomy.

Results: Histology reported a poorly cohesive carcinoma with signet-ring cell phenotype in the transverse colon invading the bowel wall and submucosa. Immunohistochemistry showed positive staining of the neoplastic cell for CK (AE1/3, CAM5.2) with focal staining for CK20 and CDX2. Micro metastases were found in the 9/11 lymph node. The histological feature was morphologically consistent with metastasis from the gastric primary.

Conclusions: Colorectal metastasis from gastric cancer may occur, although it is infrequent. When the symptoms of change in bowel habits are noticed, the possibility of metastases to the colon and rectum should be suspected. Endoscopic and CT surveillance for metastatic sites in the colon and rectum should be emphasised at postoperative check-ups during the follow-up period.

Keywords: Gastric carcinoma; metastases; neoplasms; signet-ring cell; transverse colon