S5887 An Unusual Presentation of Desmoid Fibromatosis Around Hepatic Artery

Introduction: Desmoid fibromatosis is a rare, locally aggressive soft tissue neoplasm characterized by the absence of metastatic potential. Its estimated annual incidence is 2-4 new cases per million people. Although they can form sporadically, there has been a correlation with trauma, increased estrogen states (e.g. pregnancy) or Familial adenomatous polyposis. Case Description/Methods: A 60-year-old man with previous medical history of prediabetes, hyperlipidemia, BPH, recurrent diverticulitis with intermittent hematochezia and cholecystectomy. He underwent computed tomography scan of the abdomen and pelvis for nocturia evaluation. Imaging revealed an incidental finding of abnormal soft tissue thickening in the portal region, particularly around the common and proper hepatic artery with extension into the biliary region. The lesion measured approximately 9.1 × 4.7 cm. Patient denied any associated symptoms of nausea, vomiting, weight loss, illicit drug abuse, or tobacco use. The patient subsequently underwent FNB of periportal vein/hepatic artery circumferential mass with endoscopic ultrasound (EUS) using 22-gauge needle (Boston Scientific). A single pass multiple actuations were performed using slow pull technique. The inflow Doppler setting was used to ensure that there was no bleeding post procedure. Pathology revealed benign myofibroblastic cell proliferation, favoring desmoid fibromatosis with no evidence of malignancy. Immunohistochemical staining was also positive for smooth muscle actin (SMA), β-catenin and focally positive Desmin further solidifying the diagnosis. Patient continues to be asymptomatic and has no concerns for mass effect on both imaging and serology. The patient is currently pending a fluorodeoxyglucose PET scan and is being referred to hepatobiliary surgical consultation to evaluate management options. Discussion: This case highlights a significant presentation of desmoid fibromatosis, particularly given the tumor’s complex anatomical location encasing the hepatic artery. Such involvement poses a considerable challenge to achieving margin negative resection, thereby increasing the potential of local recurrence. This patient is over 40 years of age, with no family history of colorectal cancer and no evidence of multifocal disease on imaging, making Gardner’s syndrome less likely. Nevertheless, a comprehensive oncological evaluation remains warranted to rule out occult malignancy. A multidisciplinary approach involving surgical consultation is essential to assess for resection versus active surveillance.