Abstract
BACKGROUND: Signet-ring cell carcinoma (SRCC) is a rare subtype of colorectal cancer. The incidence of primary colonic SRCC is relatively rare in pediatric patients, with a limited number of reported cases currently available. The prognosis for this specific tumor type is unfavorable, and the preoperative diagnosis presents challenges, potentially leading to misdiagnosis. This case report describes the diagnosis of primary SRCC in the colon of a 10-year-old girl. CASE SUMMARY: The patient was admitted to the hospital due to abdominal pain and vomiting. A computed tomography scan revealed an irregular mass with soft tissue density in her transverse colon, showing uneven density and multiple calcifications. The patient underwent surgical resection of the affected bowel and lymph node dissection, which was confirmed by pathological examination to be SRCC infiltrating both nerves and the entire intestinal wall. Additionally, tumor thrombus formation was observed in blood vessels and lymphatic vessels, multiple cancerous nodules were found in the omentum, and metastasis to 18 of 26 mesenteric lymph nodes examined. Immunohistochemistry for mismatch repair gene protein demonstrated microsatellite stability. No mutations in KRAS, NRAS, BRAF, or PIK3CA genes were detected through molecular pathology analysis. After surgery, she received standard chemotherapy for 8 cycles without tumor progression or other abnormalities during a 12-month follow-up period. CONCLUSION: Primary colonic SRCC is a rare malignant tumor with atypical clinical symptoms, and timely identification and intervention are crucial for improving the prognosis.