Miscellaneous Causes

Genetic diseases can be identified as rare causes of acute and recurrent pancreatitis mainly in subjects with early onset of pancreatitis and with a history of first- or second-degree relatives with unexplained pancreatitis.⁴ These inherited causes are mainly related to cystic fibrosis transmembrane conductance regulator gene mutations, and trypsinogen-gene mutations.

Autoimmune pancreatitis is also a rare entity characterised by mild pancreatitis associated with abnormal laboratory findings (e.g. elevated serum immunoglobulin (Ig)G4 levels and presence of auto- antibodies), imaging studies showing a diffusely swollen pancreas and irregular narrowing of the duct due to lymphoplasmacytic infiltration, responding favourably to steroid therapy and sometimes associated with other autoimmune disorders.⁵

Finally, very rare miscellaneous causes of ARP include vascular disorders, infections (e.g. tuberculosis, virus and parasite), and tropical pancreatitis.4 Among the patients without an obvious cause for ARP, this means that around 20% to 30% of all cases with ARP, SOD, PD and occult biliary stones and tumours are generally considered as aetiological associated factors in 30%, 20%, 20% and 10%, respectively, leaving only approximately 20% of ‘idiopathic’ ARP related to genetic, autoimmune, infectious and really unknown factors (see Figure 2).²⁰

Initial Evaluation Procedures

History and physical examination are probably the most important parts of the initial evaluation to search evidence for alcohol abuse, drug-induced pancreatitis and a family history of pancreatitis.

Routine blood tests should include liver function tests within 24 to 48 hours of onset of symptoms (a three- fold or greater increase in the alanine aminotransferase (ALT) level is generally regarded as the best indicator of gallstone-induced pancreatitis), and the serum levels of calcium and triglyceride soon after admission (because of the drop in calcium and triglyceride levels due to fasting and administration of intravenous fluids).⁸ Abdominal U/S is routinely performed in patients without previous cholecystectomy in order to detect gallbladder stones (with an accuracy of >90%).

Contrast-enhanced CT scan is usually performed either in all patients during their first episode to confirm the diagnosis of acute pancreatitis and to assess the severity,⁸ or only when the attack is severe, when the course is complicated, when aetiology remains unclear or in the elderly.²

Recently, the use of gadolinium-enhanced dynamic MRI was found to be comparable with contrast- enhanced CT for the assessment of the severity of acute pancreatitis, while avoiding the use of iodinated contrast medium and radiation, and with the ability to identify bile duct stones more accurately than CT.²¹

S-MRCP should be considered as the first-choice procedure in the diagnostic algorithm of ARP (see Figure 3), because its diagnostic accuracy in detecting the various aetiological lesions of ARP is similar to that of ERCP without carrying the risk of potential ERCP-related complications. This initial work-up during an attack of pancreatitis detects the causes of ARP in about 70% of cases^.2