Supplementary Material for: Hemorrhagic shock caused by an aggressive fibromatosis in the gastro-pancreatic region: A Case Report

Introduction ：Aggressive fibromatosis (AF), also known as desmoid tumor, is a rare condition characterized by the proliferation of monoclonal fibroblasts, primarily originating from connective tissue. Despite being histologically benign, AF exhibits malignant-like behavior, including local invasion and a high recurrence rate. AF can be classified based on its location into extra-abdominal, abdominal wall, and intra-abdominal types. Intra-abdominal AF (IAF), though least common, has the worst prognosis and highest mortality rate. Traditionally, complete surgical resection (R0) was the preferred treatment, but recent strategies favor conservative management, especially for asymptomatic patients. Emergency surgery is reserved for complications like bleeding, perforation, or obstruction. Case Presentation ：This report details a rare case of IAF in the retroperitoneum of a 39-year-old woman presenting with hemorrhagic shock. Emergency surgery, including partial distal pancreatectomy and partial gastrectomy, was performed. The tumor was β-catenin positive, confirming the diagnosis of IAF. Postoperatively, the patient recovered well and showed no recurrence after two years without additional therapy. Conclusion ：In summary, IAF presents significant diagnostic and therapeutic challenges. Effective management relies on a multidisciplinary approach, combining various diagnostic tools to improve early detection and patient outcomes. Continued research is essential to understand the pathogenesis of AF and to develop less invasive treatment options.