Abstract
Common etiologies for acute pancreatitis in inflammatory bowel disease (IBD) include medications, gallstones and autoimmune pancreatitis. Here we report a case of balsalazide-induced pancreatitis that had the radiological appearance of autoimmune pancreatitis. A seventeen-year-old male with ulcerative colitis (UC) presented with severe abdominal pain for 2 days. He was on adalimumab and balsalazide, started 8 weeks ago. Lipase was elevated to 948 units/L. CT abdomen showed biliary ductal dilatation with transition at the pancreatic head and loss of lobulated pancreatic contour. An MRI abdomen again noted loss of lobulated contour, enhancing pseudo-capsule in the pancreatic neck and increased signals in body and tail. On endoscopic ultrasound, the pancreas was diffusely hypoechoic and enlarged, and fine needle biopsy was performed of the head and neck. Immunological work-up revealed negative antinuclear antibodies and IgG4 level of 54 mg/dL. The patient was started on prednisone for presumed autoimmune pancreatitis. He had some clinical improvement and was discharged. Home medications, including balsalazide, were resumed. Pancreatic biopsy revealed degenerated inflammatory cells and fragments of necrotic tissue consistent with acute pancreatitis. He presented again with similar symptoms 5 days later. Considering temporal relationship with balsalazide and early recurrence, he was diagnosed with drug-induced pancreatitis. Balsalazide was discontinued and he has had no recurrences since. Autoimmune pancreatitis has two distinct phenotypes, type I (systemic IgG4 disease) and type II (ductcentric lymphoplasmacytic sclerosing pancreatitis, IgG4 negative). Diffuse parenchymal enlargement giving sausage-shaped appearance is the characteristic CT finding in autoimmune pancreatitis. Other abnormalities include low-attenuating rim around the pancreas, focal enlargement mimicking a tumor and diffuse pancreatic atrophy. The involved area has decreased enhancement on arterial phase and increased enhancement on delayed phase. In our patient, the presence of UC, diffuse enlargement of the pancreas and normal IgG4 led to initial diagnosis of type II autoimmune pancreatitis. However, lack of dramatic response to steroids, recurrence of pancreatitis with resumption of balsalazide and lack of recurrence since stopping it confirm the presence of drug-induced pancreatitis. This demonstrates that a sausage-shaped pancreas in this case does not imply autoimmune pancreatitis.