Fig. 17.4 Chronicpancreatitis.(A)Extensivefibrosisandatrophyhaveleftonlyresidualislets(left) andducts(right), withasprinklingofchronicinflammatorycellsandacinartissue.(B)Ahigher-powerviewdemonstratingdilatedductswithinspissatedeosinophilicconcretionsinapatientwithalcoholicchronicpancreatitis.
The diagnosis of chronic pancreatitis requires a high degree of clinical suspicion. During an attack of abdominal pain, there may be mild fever and modest elevations of serum amylase. In end-stage disease, however, acinar destruction may be so advanced that enzyme elevations are absent. Gallstone-induced obstruction may manifest as jaundice or elevated levels of serum alkaline phosphatase. A very helpful finding is visualization of calcifications within the pancreas by CT or ultrasonography. Weight loss and hypoalbuminemic edema from malabsorption caused by pancreatic exocrine insufficiency can also point to the disease.
Although chronic pancreatitis is usually not acutely life-threatening, the long-term outlook is poor, with a 50% mortality rate over 20 to 25 years. The most common longterm sequelae of chronic pancreatitis is insufficiency of pancreatic exocrine enzymes, with consequent malabsorption and deficiency of fat-soluble vitamins (Chapter 8). Exocrine insufficiency typically predates endocrine dysfunction, and patients with severe loss of islets can develop diabetes mellitus (Chapter 20). In other patients, severe chronic pain may dominate the clinical picture. Pancreatic pseudocysts (discussed earlier) develop in about 10% of patients. The most feared long-term complication of chronic pancreatitis is pancreatic cancer. The risk for malignant transformation in adult-onset disease is modest, with no more than 5% of patients developing cancer at 20 years. In contrast, chronic pancreatitis that begins in childhood, such as hereditary pancreatitis secondary to PRSS1 mutations, confers a 40% to 55% lifetime risk for pancreatic cancer. It is not unusual for patients with PRSS1 mutations to undergo prophylactic pancreatectomy.
•Acute pancreatitis ischaracterizedbyinflammationandreversibleparenchymaldamagethatrangesfromfocaledemaandfatnecrosistowidespreadparenchymalnecrosisandhemorrhage;theclinicalpresentationvarieswidely,frommildabdominalpaintorapidlyfatalvascularcollapse.
Chronic pancreatitis ischaracterizedbyirreversibleparenchymaldamageandscarformation;clinicalpresentationsincludechronicmalabsorption(duetopancreaticexocrineinsufficiency)anddiabetesmellitus(duetoisletcellloss).
Bothentitiessharesimilarpathogenicmechanisms,andindeedrecurrentacutepancreatitiscanresultinchronicpancreatitis.Ductal obstruction andlong-term alcohol abuse arethemostcommoncausesinbothforms.Inappropriateactivationofpancreaticdigestiveenzymes(duetomutationsingenesencodingtrypsinogenortrypsininhibitors)andprimaryacinarinjury(duetotoxins,infections,ischemia,ortrauma)alsocausepancreatitis.
Pancreatic exocrine neoplasms can be cystic or solid. Some tumors are benign, while others are among the most lethal of all malignancies.