Gastrointestinal stromal tumor of the rectum resected by transanal total mesorectal excision after neoadjuvant imatinib treatment: A case report

Abstract

This report describes the combination of a transanal total mesorectal excision (TaTME) and neoadjuvant therapy with Imatinib mesylate (IM) for a gastrointestinal stromal tumor (GIST) of the lower rectum. A 49-year-old man presented with a submucosal tumor with ulcer located 3 cm above the anal verge. Histopathologically, a biopsy showed spindle-shape cells, positive for C-kit and CD34, negative for smooth muscle actin, desmin and S-100 protein. Genetically, this GIST had the mutation in KIT exon 11. IM (400 mg/d) was administered as neoadjuvant therapy for 80 days. The GIST shrank from 4.7 to 3.3 cm in diameter. Abdominal and trans