Obstructive jaundice due to retroperitoneal desmoid-type fibromatosis: a case report and review of literature.

Introduction and importance: Desmoid-type fibromatosis (DF) is a rare, benign fibroblastic tumor arising from musculoaponeurotic structures. Despite lacking metastatic potential, it can be locally aggressive. Retroperitoneal DF is uncommon, and its presentation with obstructive jaundice is extremely rare. Case presentation: A 55-year-old male with no significant medical or family history presented with a six-month history of right upper quadrant abdominal pain and three weeks of progressive jaundice. Laboratory findings revealed a cholestatic pattern and elevated CA 19-9. Imaging, histopathological examination and immunohistochemistry were consistent with desmoid-type fibromatosis. The patient was managed with palliative chemotherapy and percutaneous transhepatic biliary drainage (PTBD) to relieve biliary obstruction. Clinical discussion: Retroperitoneal DF is typically managed with surgical excision or watchful waiting, depending on the location and symptoms. While surgical resection is preferred, it is often not feasible in cases involving extensive invasion. In this case, chemotherapy served as the primary treatment modality due to the tumor's unresectability. Conclusion: This case highlights the importance of including retroperitoneal desmoid-type fibromatosis in the differential diagnosis of obstructive jaundice and underscores the need for larger studies and updated management guidelines.