Anorectal gastrointestinal stromal tumor mimicking prostatic tumor on CT and MRI

We report a case of gastrointestinal stromal tumor (GIST) arising from the rectum which mimicked prostatic tumor on computed tomography (CT) and magnetic resonance imaging (MRI). Most GISTs arise in the stomach and/or small intestine; GISTs of anorectal origin are rare. We identify characteristic CT and MRI findings of anorectal GISTs and discuss the diagnostic pitfalls.