Pseudocyst Pancreatitis – Top USMLE Diseases

Chronic pancreatitis is due to persistent inflammation, fibrosis, and irreversible cell damage to the pancreas, resulting in a loss of endocrine and exocrine gland function. The most common etiologies are alcohol abuse and pancreatic duct obstruction. Patients often present with recurrent epigastric abdominal pain, nausea, and features of malabsorption syndrome (diarrhea, steatorrhea, and weight loss). Characteristic computed tomography (CT) findings include pancreatic atrophy, dilated pancreatic ducts, and pancreatic calcifications. Therapy focuses on alcohol cessation, diet changes, pain management, and treatment of pancreatic insufficiency.

The pancreas is a composite organ containing a distinctive combination of cell lineages. The exocrine tissue comprises acinar cells, which secrete digestive enzymes into the intestine. The endocrine function is performed by the islets of Langerhans, which consist of distinct cell types secreting 4 different hormones into the circulation (α-cells, glucagon; β-cells, insulin; δ-cells, somatostatin; and γ-cells, pancreatic polypeptide). Endocrine hormones, as well as some exocrine enzymes, can be measured in body fluids and provide important diagnostic information in acute and chronic pancreatic disease.

Opiates are drugs that are derived from the sap of the opium poppy. Opiates have been used since antiquity for the relief of acute severe pain. Opioids are synthetic opiates with properties that are substantially similar to those of opiates. Known for their remarkable efficacy, opioids induce their effects (analgesia, euphoria, and sedation) by interacting with opioid receptors (μ, κ, and δ) in the nervous system. Opiates/opioids have adverse effects that include respiratory depression, nausea and vomiting, decreased GI motility and constipation, tolerance, dependence, and addiction.

Pancreatic cancer, consisting mostly of invasive pancreatic ductal adenocarcinoma (PDAC), arises from the ductal cells of the exocrine pancreas and is the 4th leading cause of cancer-related deaths in the United States. Pancreatic cancer has the highest mortality rate among the major cancers, with a 5-year survival rate of only 8%–10%. Clinical presentation includes symptoms of abdominal pain, jaundice, and weight loss. Diagnosis is made by CT, MRI, and endoscopic ultrasonography (EUS). Management by surgical resection, usually with neoadjuvant or adjuvant chemotherapy, provides the only chance for cure in the 15%–20% of patients who have resectable disease at the time of diagnosis. Other rare malignant tumors arising from the exocrine pancreas are acinar cell carcinoma and pancreatoblastoma.

Pancreatic neuroendocrine tumors (PanNETs) arise from the endocrine pancreas (islet cells) and represent 2%–5% of primary pancreatic neoplasms; the other 95%–98% of pancreatic neoplasms are from the exocrine pancreas. The majority of PanNETs are nonfunctional (50%–75%), while others that are functional may be benign or malignant. Benign or malignant PanNETs include insulinomas, gastrinomas, malignant pancreatic neuroendocrine carcinomas, and very rare tumors named glucagonomas, somatostatinomas, and VIPomas, after the hormones they secrete. Diagnosis is made clinically, with lab testing for hormone secretion, as well as imaging or upper endoscopy. Management is surgical or with newer molecularly targeted therapies.

The pancreas lies mostly posterior to the stomach and extends across the posterior abdominal wall from the duodenum on the right to the spleen on the left. The pancreas is covered with a very thin connective tissue capsule that extends inward as septa, partitioning the gland into lobules. This organ has both exocrine and endocrine tissue. The exocrine portion is organized in grape-like clusters of acini, which are small sacs surrounding the terminal ends of pancreatic ducts. The cells lining the acini and ducts secrete products that make up pancreatic juices, which play a major role in digestion. The endocrine portion of the gland consists of circular islets interspersed between acini, which secrete glucagon, insulin, and somatostatin.