[A case of inferior vena cava thrombosis and acute pancreatitis in a patient with ulcerative colitis].

A 21-year-old man admitted complaining of sudden severe epigastric pain for 1 day. He had been diagnosed as ulcerative colitis (UC) and taking mesalazine for two months. UC was in nearly complete remission at admission. He never drank an alcohol, and serum amylase was 377 IU/L. CT scan showed inferior vena cava (IVC) thrombosis in addition to mild acute pancreatitis. To evaluate the cause of acute pancreatitis and IVC thrombosis, magnetic resonance cholangiopancreatogram (MRCP), endoscopic ultrasonogram (EUS), lower extremity Doppler ultrasonogram (US) and blood test of hypercoagulability including factor V, cardiolipin Ab, protein C, protein S1, antithrombin III, and anti phospholipids antibody were performed. There was no abnormality except mild acute pancreatitis and IVC thrombosis in all the tests. He was recommended to stop taking mesalazine and start having anticoagulation therapy. After all symptoms disappeared and amylase returned normal, rechallenge test with mesalazine was done. Flare-up of abdominal pain occurred and the elevation of serum amylase was observed. Ulcerative colitis came to complete remission with short-term steroid monotherapy. Acute pancreatitis and IVC thrombosis were completely resolved after 3-month anticoagulation therapy with no more mesalazine. We postulated that IVC thrombosis occurred due to hypercoagulable status of UC and intra-abdominal inflammation caused by mesalazine-induced pancreatitis.