Vesicocutaneous fistula formation during treatment with sunitinib malate: Case report

BACKGROUND: The oral multi-kinase inhibitor sunitinib malate improves the survival of patients with gastrointestinal stromal tumors (GIST) after the disease progresses or intolerance to imatinib mesylate develops. Urinary fistulae arising during treatment with sunitinib for GIST have not been described. CASE PRESENTATION: We describe a 62-year-old female patient diagnosed with unresectable GIST that involved the abdominal wall, urinary bladder wall, bowel, mesentery and peritoneum in the pelvic cavity. Intestinocutaneous fistulae developed on a surgical lesion after orally administered imatinib was supplemented by an arterial infusion of 5-flurouracil. Sunitinib was started after the patient developed resistance to imatinib. On day 4 of the fourth course of sunitinib, a widely dilated cutaneous fistula discharged large amounts of fluid accompanied by severe abdominal pain. Urinary communication was indicated based on the results of an intravenous injection of indigo carmine. Computed tomography findings suggested a small opening on the anterior urinary bladder wall and fistulous communication between the bladder and abdominal walls bridged by a subcutaneous cavity. The fistula closed and the amount of discharge decreased when sunitinib was discontinued. Therefore, sunitinib might have been associated with the development of the vesicocutaneous fistula in our patient. CONCLUSION: This is the first description of a vesicocutaneous fistula forming while under sunitinib treatment. Clinicians should be aware of the possible complication of vesicocutaneous fistula formation during treatment with molecular targeting agents in patients with extravesical invasion and peritoneal dissemination of GIST.