A 45-year-old male presents with weight loss, steatorrhea, and malabsorption. A CT scan of the abdomen reveals a questionable mass in the head of the pancreas. A biopsy specimen microscopically reveals chronic inflammation and atrophy of the pancreatic acini with marked fibrosis. No malignancy is identified. What is the most common cause of this patient's disease in adults?

Chronic pancreatitis is characterized histologically by chronic inflammation and irregular fibrosis of the pancreas. The major cause of chronic pancreatitis in adults is chronic alcoholism, while in children the major cause is cystic fibrosis. Recurrent attacks of acute pancreatitis also result in the changes of chronic pancreatitis. Hypercalcemia and hyperlipidemia also predispose to chronic pancreatitis (since they are causes of acute pancreatitis), while in as many as 10% of patients, recurrent pancreatitis is associated with pancreas divisum. This condition refers to the finding of the accessory duct being the major excretory duct of the pancreas. Chronic ductal obstruction may be a cause of chronic pancreatitis and may be associated with gallstones, but it is more appropriate to relate gallstones with acute ductal obstruction and resultant acute pancreatitis. Complications of chronic pancreatitis include pancreatic calcifications, pancreatic cysts and pseudocysts, stones within the pancreatic ducts, diabetes, and fat malabsorption, which results in steatorrhea and decreased vitamin K levels. Reference: Robbins & Cotran Pathologic Basis of Disease, 9edition