| Discussion: |
Alcoholism and biliary tract disease cause the majority of cases of pancreatitis in the United States. Other causes include hypercalcemia, Type I and Type IV hyperlipidemia, viral infection (mumps and hepatitis), mononucleosis, drugs, trauma, penetrating gastric ulcer and structural abnormalities (i.e., pancreas divisum) in children. Trauma, systemic diseases and drugs are most common. At least 20% of patients have no predisposing condition.
CT findings vary with severity. 20-30% of patients will have a normal CT scan. Disease may be focal or diffuse. The attenuation of the involved areas of pancreas is decreased. Focal abnormality in the head of the pancreas is best differentiated from neoplasm on clinical grounds. Since there is no pancreatic capsule, spreading inflammation can involve the peripancreatic soft tissues. Spread occurs into the region of the lesser sac and left anterior pararenal space. Posteriorly spread is limitied by Gerota's Fascia. The perinephric fat stands out on plain film and is the basis of the "renal halo" sign. The bowel mesentery can also be involved. Dilation of the pancreatic duct can be seen.