Multifocal Intraluminal Gastric and Colonic Recurrence of Anorectal Signet-ring Cell Carcinoma: A Case Report
MADELINE YEN MIN CHEE, WENJIE LIN, SIMON YEW KUANG ONG, JIANBANG CHIANG, NGO NYE THANE and ISAAC SEOW-EN

Extra-anastomotic intraluminal recurrence of colorectal cancer (CRC) is uncommon. A 44-year-old female underwent abdominoperineal resection for non-metastatic, stenosing anorectal cancer. Histopathology showed a T4aN2b poorly-differentiated signet-ring cell carcinoma. Postoperative chemoradiotherapy was completed. Twelve months post-surgery, serum carcinoembryonic antigen (CEA) level was elevated, with colonoscopy showing a right-sided malignant lesion on biopsy. Right colectomy was performed, with extensive tumour deposits found on the resected specimen. Morphological features, immunoprofile and molecular profile of the tumours were consistent with metastases from the previous anorectal primary. Gastroscopy also revealed multifocal small gastric polyps with identical signet-ring cell features. Palliative chemotherapy was commenced, with the patient eventually succumbing to the disease. Reported here is the first known case of multifocal intraluminal recurrence in the right colon and stomach from an anorectal cancer, likely from implantation metastases. Further studies are warranted to shed light on the mechanisms involved in this rare form of CRC metastasis.