Giant mesenteric fibromatosis progresses despite targeted therapy and immunotherapy in case reportOne patient with a giant tumor progressed despite targeted therapy and immunotherapy

Mesenteric fibromatosis (MF) is a rare, locally aggressive, borderline tumor with no metastatic potential, characterized by a high postoperative recurrence rate. This paper reports a complex case of aggressive MF. Despite receiving targeted therapy that was combined with immunotherapy, the tumor in our case progressed rapidly and symptoms of intestinal obstruction developed. Following a challenging radical resection, delayed and complex multiple complications ensued, including duodenal fistula, vaginal fistula, and ureterorectal fistula. Through personalized management under multidisciplinary team (MDT) collaboration—including adequate drainage to control infection, stepwise nutritional support (i.e., transitioning from total parenteral nutrition to enteral nutrition), and targeted management of a high-output enterostomy—the patient ultimately recuperated with drainage tubes in place, and she was able to tolerate oral feeding. This case suggests that for giant mesenteric fibromatosis that continues to progress despite medical therapy, close imaging surveillance (particularly vigilance for signs of "tension cystic change") should be employed to warn of serious complications, and a decisive, surgery-centered multidisciplinary comprehensive treatment strategy should be adopted. Postoperatively, reliance on a multidisciplinary team is essential for long-term vigilance against delayed complex fistulae triggered by factors such as infection. The diagnostic and therapeutic experience from this case provides an important reference for managing this highly challenging disease.