Autoimmune Acquired Factor V Deficiency in a Patient With Pancreatic Cancer Complicated by Cholangitis: A Rare Coagulopathy With a Favorable Course.

Autoimmune acquired factor V deficiency (AiFVD) is a rare bleeding disorder characterized by the presence of inhibitors against coagulation factor V (factor V). It can manifest with a wide spectrum of clinical severity, from asymptomatic to life-threatening bleeding. Various underlying causes have been reported, including malignancies, autoimmune disorders, infections, and antibiotics. However, the mechanism remains unclear, and diagnostic delays are common due to its rarity. A 78-year-old woman with pancreatic head cancer underwent bile duct stenting for malignant biliary stricture. She subsequently developed cholangitis from stent obstruction, accompanied by coagulopathy. Coagulation studies revealed a prolonged prothrombin time of 68.1 seconds, an activated partial thromboplastin time exceeding 283.7 seconds, and severely reduced FV activity (<3%). A cross-mixing test suggested the presence of an inhibitor, leading to the diagnosis of AiFVD. The coagulopathy resolved following treatment of the underlying cholangitis. AiFVD can arise from various causes; in this case, it was attributed to cholangitis caused by recurrent biliary obstruction.