A silent killer mimicking appendicitis: primary signet-ring cell carcinoma of the colon in a child—case report and literature review

Introduction Signet-ring cell carcinoma (SRCC) of the colon is extremely rare and highly aggressive in children. Presentation as an acute abdomen is uncommon and may mimic acute appendicitis, delaying diagnosis. Case presentation A 10-year-old boy with no relevant personal or family history presented with a 2-day history of abdominal pain, initially epigastric and then localized to the right iliac fossa, with vomiting, preceded by 4 weeks of general deterioration. Fever (38.2 °C), right iliac fossa tenderness and leukocytosis (19,000/mm 3 ) suggested complicated appendicitis, but computed tomography showed a stenosing mass of the transverse colon with proximal dilatation. Emergency laparotomy revealed generalized peritonitis and a stenosing mid-transverse colon tumor without gross metastasis, and an extended right hemicolectomy with a double-barrel stoma was performed. Histology showed a primary SRCC (pT3 pN2b, 7/22 lymph nodes; stage IIIC), MMR-proficient and KRAS/NRAS/BRAF wild-type. Despite adjuvant FOLFOX, pulmonary and peritoneal metastases developed within six months, and the patient died 9 months after diagnosis. Discussion A structured literature search (PubMed/MEDLINE, Europe PMC and complementary sources, January 1987 to May 2026) identified 29 reports describing 38 pediatric patients with colonic SRCC or a signet-ring cell component (age 6–18 years, median 14). Abdominal pain (30 of 35 patients) and obstruction or intussusception (at least 17) predominated; mismatch repair (MMR)/microsatellite instability (MSI) status was reported for only 12 patients, all proficient or stable, and 15 of the 23 patients with known outcome died of their disease. In a child with an atypical course (general deterioration, weight loss or obstruction), preoperative cross-sectional imaging can reveal the colonic tumor and allow oncological resection. Every pediatric colorectal carcinoma should undergo MMR/MSI and RAS/BRA F testing, germline evaluation and, where available, broader tumor profiling to detect hereditary syndromes and the rare actionable targets.