Solitary Rectal Metastasis from Primary Gastric Cancer.

A 47-year-old man with a history of distal gastrectomy presented with epigastric pain. Esophagogastroduodenoscopy revealed advanced diffuse infiltrative cancer at the site of anastomosis of the remnant stomach (Picture 1A). Biopsy revealed poorly differentiated adenocarcinoma (Picture 1B, Hematoxylin ＆ Eosin staining, ×200). Abdominal computed tomography showed lymph node swelling but no metastasis to other organs. Colonoscopy revealed a flat elevated rectal lesion of 5 mm in diameter (Picture 1C, arrows) with a shallow depression (Picture 1D); however, no other neoplastic lesions were detected. The rectal lesion, which consisted of a poorly differentiated adenocarcinoma located in the submucosa, was removed by endoscopic mucosal resection (Picture 2A). The tumor had no intraepithelial components such as adenoma or carcinoma in situ (Picture 2B). Immunohistochemistry revealed that the tumor cells were CK7+, CK20− (Picture 2C-E), CDX2+ and p53+, which was identical to the gastric cancer (Picture 2F-H). The tumor was histologically and immunohistochemically similar to the gastric cancer, was mainly located in the submucosa, and lacked an intraepithelial component indicating solitary rectal metastasis.

Picture 1.

Picture 2.

In most colorectal metastasis from gastric cancer occurs a multiple metastases or is of an advanced stage (1); there is only one reported case of early-stage solitary metastasis (2). However, the differential diagnosis of a solitary diminutive colorectal lesion in a patient with a history of gastric cancer should include metastatic disease.

The authors state that they have no Conflict of Interest (COI).