Multifocal Mesenteric Desmoid-Type Fibromatosis After Liver Transplantation: A Case Report

BACKGROUND Desmoid-type fibromatosis (DTF) is a locally aggressive borderline mesenchymal neoplasm characterized by abnormal proliferation of spindle-shaped cells and deposition of collagenous matrix. Although intra-abdominal DTF is rare, it predominantly involves the mesentery, and its clinical presentations and imaging features frequently overlap with gastrointestinal stromal tumors (GISTs) or sarcomas. Complete surgical resection remains the primary curative approach; however, postoperative recurrence rates are notably high. Moreover, multifocal lesions (with concurrent involvement of intestinal segments II and III, as demonstrated in this case) indicate a more aggressive biological behavior. This report focuses on an incidental diagnosis of multifocal DTF following liver transplantation. CASE REPORT We herein report a case of a 46-year-old female patient who presented with a hypoechoic inter-intestinal mass of undetermined nature in the mid-abdominal region during post-liver transplantation surveillance. Firstly, abdominal ultrasound revealed a hypoechoic mass within the right inter-intestinal space. Secondly, non-contrast abdominal computed tomography (CT) identified a well-demarcated soft tissue mass within the mesenteric fat space in the lower abdomen. Finally, surgical intervention was performed, and postoperative histopathological examination revealed findings consistent with mesenteric DTF (MDF), accompanied by reactive hyperplasia of mesenteric lymph nodes. CONCLUSIONS In this case we systematically excluded differential diagnoses, including GIST and leiomyosarcoma, through histopathological and immunohistochemical analyses, thereby underscoring the pivotal role of comprehensive histopathological evaluation in the diagnosis of DTF. This case report aims to enhance the understanding of the disease's distinctive pathological features and key points of differential diagnosis, while providing practical reference for the management of complex clinical cases.