Abstract
BACKGROUND: Rectal tumors extending to the dentate line (RTDL) represent a distinct subtype of rectal neoplasms due to the unique anatomical features of the dentate line, for which endoscopic submucosal dissection (ESD) has proven to be an effective therapeutic approach. Furthermore, when tumors invade diverticula, the likelihood of perforation during ESD markedly escalates. Reports detailing the simultaneous management of these three high-risk factors-large tumor size, involvement of the dentate line, and association with a diverticulum-are scarce. Thus, this paper outlines the diagnostic and therapeutic process for a patient who underwent successful endoscopic resection of a huge rectal tumor with these combined challenging features by ESD. CASE SUMMARY: A 70-year-old male patient was admitted with a history of "altered bowel habits" persisting for 2 years. Subsequent examinations, including a colonoscopy, led to the diagnosis of a lesion with high-grade intraepithelial neoplasia and focal intramucosal carcinoma. The lesion, measuring approximately 7 cm × 8 cm, extended to the dentate line and was accompanied by a diverticulum. Following a multidisciplinary consultation, the patient underwent radical resection through endoscopic submucosal dissection (ESD). The procedure successfully managed the affected diverticulum without complications. Postoperative histological analysis of the en bloc specimen confirmed a conventional serrated adenoma with high-grade intraepithelial neoplasia and focal intramucosal carcinoma (pTis). The resection margins were negative (R0 resection), and there was no lymphovascular invasion. At 1-year postoperative follow-up, no tumor recurrence or distant metastasis was observed, and anal function was preserved. CONCLUSION: This case demonstrates the feasibility and curative effect of ESD for large intramucosal rectal carcinoma involving the dentate line and associated with a diverticulum. However, larger cohort studies and long-term follow-up are required to validate the generalizable safety and efficacy of this approach.