Zikai Zhou, Qingbin Wu, Wenjian Meng
A 61-year-old man with a history of rectal cancer surgery developed a recurrent lesion in the transverse colon after repeated endoscopic resections. Histopathology initially showed high-grade intraepithelial neoplasia and subsequently intramucosal adenocarcinoma with negative deep margins, yet the lesion recurred within 1 month. Histopathological initially showed high-grade intraepithelial neoplasia and subsequently later intramucosal adenocarcinoma with negative deep margins, yet the lesion recurred within 1 month. At our institution, colonoscopy demonstrated a 2.0 cm elevated lesion, whereas cross-sectional imaging revealed neither regional lymphadenopathy nor distant metastatic disease. Because the rapid recurrence was inconsistent with the apparently favorable pathological findings, laparoscopic-endoscopic cooperative full-thickness resection was undertaken to achieve definitive excision and pathological assessment while maintaining bowel continuity. Examination of the resected specimen disclosed moderately differentiated adenocarcinoma extending into the subserosa (pT3), with negative margins, low-grade tumor budding, no lymphovascular or perineural invasion, and retained mismatch repair protein expression. Although oncologic colectomy with regional lymphadenectomy remains the standard treatment for pT3 colon cancer, completion colectomy was omitted after multidisciplinary review and shared decision-making. This exceptional decision reflected the absence of radiographic nodal or distant disease, favorable pathological features, the patient's previous ultra-low colorectal anastomosis, the anticipated functional burden of further surgery, and his informed preference. At approximately 21 months of follow-up, no recurrence had been detected. However, occult nodal disease cannot be excluded, and this approach should not be considered an alternative to standard oncologic surgery.