eP172 - Kraske Procedure for a Presacral Gastrointestinal Stromal Tumor of the Lower Rectum

Purpose/Background: Rectal gastrointestinal stromal tumor (GIST) is rare, comprising about 4% of all GISTs. Management includes resection of the tumor with negative margins, with or without neoadjuvant imatinib therapy. For exophytic distal tumors sparing the sphincter muscles, the pre-sacral approach (classically known as the Kraske procedure) is an option.Methods/Interventions: In this case report, we retrospectively review the management of a woman with a lower rectal GIST located in the presacral space.Results/Outcomes: A 78-year-old female presented with changes in bowel habits, fecal urgency and incontinence. Digital rectal exam revealed a firm lesion causing external compression at the posterior rectum. Imaging revealed a 9.3 x 7.5 x 8.5 cm rectal mass in the presacral space, with the posterior aspect extending to the tip of the coccyx (figure 1). Core needle biopsy confirmed a diagnosis of GIST (KIT positive on immunohistochemistry). She was treated with 13 months of neoadjuvant imatinib, with a partial response by RECIST. She underwent a Kraske procedure through a posterior midline incision. The tumor appeared to arise from the posterior rectal wall with no sphincter involvement. An associated lesion was found just superior to this within the presacral space. A portion of the posterior rectal wall was excised en bloc with the tumor, preserving the mucosa; the rectal wall was reapproximated primarily. A drain was placed in the presacral space, and the wound was closed in layers. Pathology revealed 8.2 cm spindle-cell type tumor with 2.2 cm associated lesion; post-treatment mitotic rate was 0. The patient recovered well and her drain was removed in clinic. She reported resolution of fecal urgency and return of normal bowel movements. She started adjuvant imatinib therapy with plans for follow up imaging in 3 months.Conclusion/

Discussion: This case highlights the rare presentation of a presacral GIST of the lower rectum. Despite the large size of the tumor presented in this case, it was safely removed through a posterior approach, and the patient recovered uneventfully. The Kraske approach provides excellent exposure for distal presacral GISTs and may be considered for the surgical management in select patients.Figure 1Preoperative MRI