Complex Case of Aggressive Intra-abdominal Desmoid-type Fibromatosis Status Post Cholecystectomy

: Desmoid-type fibromatosis (DF), also known as desmoid tumor, is an extremely rare, benign, mesenchymal fibrous tumor with no potential for metastasis. It can arise from any part of the body, most commonly extra-abdominally. Intra-abdominal DF can present sporadically, in sites of previous trauma, surgical scars and irradiation, or in association with familial adenomatous polyposis and Gardner syndrome. Intra-abdominal DF is uncommon and especially rare after a common surgery like cholecystectomy. We report a rare case of a 67-year-old male who presented with a locally aggressive intra-abdominal DF in the gallbladder fossa, status post cholecystectomy. This progressively enlarging infiltrative enhancing solid mass in the gallbladder fossa on serial computed tomography and magnetic resonance imaging demonstrated gastric outlet obstruction, biliary obstruction, portal vein narrowing and encasement of hepatic artery. Diagnosis of DF in this postoperative setting was delayed and challenging due to uncharacteristic clinical presentation. Radiologists should be aware of this unusual diagnosis and spectrum of imaging findings to help in timely surgical management and planning.