Transanal minimally invasive surgery for rectal gastrointestinal stromal tumor using articulated forceps after neoadjuvant chemotherapy with imatinib mesylate.

Rectal gastrointestinal stromal tumors (GISTs) are rare, accounting for approximately 5% of all GISTs and 0.1% of all rectal malignancies. Radical resection without capsule violation is the standard treatment for localized GISTs. However, surgical resection of large rectal GISTs poses challenges because of the narrow pelvic anatomy and the need to preserve excretory function. Based on KIT mutation status, neoadjuvant imatinib therapy facilitates tumor shrinkage and improves surgical outcomes. A 72-year-old man presented with dyschezia and hematochezia. Colonoscopy revealed a submucosal rectal tumor measuring 3 cm from the anal verge, which was diagnosed as a GIST based on biopsy findings (c-kit and DOG1 positive). Imaging studies confirmed the presence of a 5-cm tumor with significant 18F-FDG uptake. KIT mutation analysis revealed a rare exon 13 K642E mutation associated with imatinib sensitivity. Neoadjuvant imatinib therapy was administered for four months, which led to tumor shrinkage to 2.5 cm in diameter. Transanal minimally invasive surgery (TAMIS) was performed with curative intent, utilizing ArtiSential articulated forceps. Full-thickness resection was achieved without capsule violation. The patient had no postoperative complications and had retained full anal function. This case highlights the utility of a multimodal approach combining neoadjuvant imatinib therapy and TAMIS to manage large rectal GISTs. TAMIS facilitated complete tumor removal while preserving excretory function and avoiding extensive surgeries, such as total mesorectal excision. Notably, this is the first report of ArtiSential articulated forceps utilized in TAMIS, demonstrating their innovative potential in enhancing surgical precision and outcomes in challenging pelvic procedures. Supplementary Information: The online version contains supplementary material available at 10.1007/s13691-025-00786-7.