[A Case of Maintenance Chemotherapy for Appendiceal Carcinoma with Signet-Ring Cell Carcinoma]

Signet ring cell carcinoma(SRCC)is a poorly prognostic cancer that primarily arises in the stomach. Its occurrence in the colon is extremely rare, with an incidence rate of 1%. We encountered a case of signet ring cell carcinoma that was considered to originate from the cecum based on clinical course and imaging findings.

A 69-year-old male had experienced abnormal bowel movements since last year and noticed abdominal distension since this year. He was referred to our hospital for further examination and treatment after a colonoscopy by a previous physician was difficult to perform. Physical examination revealed no abdominal distension or tenderness. Blood tests showed a mildly elevated tumor marker, with CEA at 5.5 ng/mL. Abdominal CT revealed stenosis centered on the terminal ileum with small bowel dilation. An ileus tube was placed the same day, and ileus tube imaging confirmed the stenosis of the terminal ileum. Diagnostic laparoscopy showed extensive peritoneal dissemination causing small bowel and sigmoid colon stenosis, and the ileocecal region was thickened and firmly adhered to the abdominal wall. Resection of the ileocecal region was deemed difficult, so a small bowel resection and ileostomy were performed. No other primary lesions were detected on imaging. Pathological examination of the ileal lesion revealed moderately to poorly differentiated adenocarcinoma/signet ring cell carcinoma primarily in the subserosal and muscular layers, suggesting cecal cancer with small bowel invasion and peritoneal dissemination. Genetic testing showed RAS wild-type, BRAF V600E wild-type, MSI negative, and HER2 negative. Chemotherapy (FOLFOX+Bmab)was initiated. Due to peripheral neuropathy and neutropenia, the dosage was reduced to 80% from the 6th course, but a total of 7 courses were administered. The patient has been free from disease progression for 8 months since the initial diagnosis.

We experienced a case of cecal cancer with peritoneal dissemination accompanied by signet ring cell carcinoma, where maintenance chemotherapy proved effective.