Transanal minimally invasive surgery for a rectal tubulovillous adenoma with high-grade dysplasia: a case report.

We presented the case of a 48-year-old woman with a history of thyroid cancer under treatment, who was referred for evaluation of a long-standing sensation of a foreign body in the anal region, associated with occasional rectal bleeding. Physical examination and rigid rectoscopy revealed a polypoid lesion 3-4 cm from the anal verge. Laboratory tests were within normal limits. Pelvic magnetic resonance imaging (MRI) showed a solid, stenosing lesion 27 mm from the anal verge, infiltrating the muscular layer without mesorectal fascia involvement, measuring 73 mm longitudinally and 51 mm in both anteroposterior and transverse diameters, classified as a mid-to-low rectal tumor T3N0M0. Initial biopsy demonstrated a tubular adenoma with focal high-grade dysplasia and extensive low-grade dysplasia. Given the MRI findings suggesting invasion, colonoscopy with targeted biopsy was performed, confirming a tubular adenoma with high-grade dysplasia. The patient underwent transanal minimally invasive surgery (TAMIS), with complete excision of a friable, irregular lesion ~5 cm in diameter. Final histology reported a tubulovillous adenoma with focal high-grade dysplasia and low-grade dysplasia, with clear resection margins. Postoperative recovery was uneventful, and the patient remains asymptomatic during follow-up. This case highlights the role of TAMIS as a safe and effective organ-preserving technique for selected rectal adenomas with high-grade dysplasia, allowing complete excision and rapid recovery.