114 Disorders of the Pancreas
Disorders of the pancreas (Figure 114-1) are rare in childhood but can be associated with significant morbidity and mortality. Pancreatitis occurs less frequently in children than in adults and can be either acute or chronic in nature. It can be complicated by shock, hypocalcemia, pseudocyst formation, or necrosis, but these complications are rare. Pancreatic insufficiency (PI), defined as insufficient lipase secretion resulting in fat malabsorption, affects about 80% to 90% of patients with cystic fibrosis (CF). Congenital anomalies of the pancreas, such as pancreas divisum and annular pancreas, are found in approximately 10% of the general population and are generally asymptomatic but can be associated with pancreatitis (pancreas divisum) or duodenal obstruction (annular pancreas).
Etiology and Pathogenesis
Pancreatitis
The frequency of pancreatitis (i.e., inflammation of the pancreas) in children and adolescents has been increasing over the past 10 to 15 years. There are several common causes of pancreatitis, including blunt abdominal trauma; infections such as enterovirus, Epstein-Barr virus, hepatitis A, rubella, Coxsackie virus B, cytomegalovirus, HIV, and influenza; congenital anomalies of the pancreas; choledochal cysts; and choledocholithiasis. Medications, including azathioprine, 6-mercaptopurine, glucocorticoids, valproate, and L-asparaginase, can cause pancreatitis. Pancreatitis can also be the result of systemic diseases and metabolic abnormalities, including CF, diabetic ketoacidosis, hypercalcemia, hyperlipidemia, and hemolytic-uremic syndrome.
Pancreatitis occurs when intracellular trypsinogen and other digestive enzymes are activated, leading to damage of the pancreatic acinar cells. This damage leads to pancreatic edema (Figure 114-2), a local inflammatory response, and the initiation of autodigestion of the pancreas. These pancreatic secretions may form a collection that becomes walled off by granulation tissue to form a pseudocyst.
Chronic pancreatitis occurs with recurrent episodes of acute pancreatitis, leading to chronic inflammation as well as end-stage fibrosis (see Figure 114-2). The most common causes of chronic pancreatitis in children are CF, hereditary pancreatitis including mutations in the SPINK1, CFTR, and PRSS1 genes, and idiopathic causes.
Cystic Fibrosis
Pancreatic insufficiency in patients with CF is caused by dysfunction of the CFTR gene (Figure 114-3). This leads to impaired transport of sodium and chloride and subsequent obstruction of the pancreatic ducts with viscous exocrine fluid. These patients have diminished secretion of amylase, lipase, colipase, and phospholipases, as well as a decreased concentration of bicarbonate in their pancreatic secretions.
Congenital and Inherited Anomalies
Congenital anomalies of the pancreas arise during fetal development. The pancreas forms from fusion of dorsal and ventral buds, which develop from the embryonic foregut. The ventral process rotates at about the eighth week of gestation and settles posterior and inferior to the dorsal portion of the pancreas. Pancreas divisum is the most common pancreatic anomaly and occurs when the dorsal and ventral portions fail to fuse. Annular pancreas occurs when the ventral bud fails to rotate with the duodenum and instead surrounds it (Figure 114-4).
Pancreatic disease may present as part of an inherited syndrome. This category includes CF and hereditary pancreatitis (see above). In addition, Schwachman-Diamond syndrome is caused by mutations in SDS and is characterized by short stature, variable neutropenia, and PI. The latter often improves as patients grow older. Finally, the spectrum of abnormalities seen in Johanson-Blizzard syndrome includes progressive PI.
Clinical Presentation
Pancreatitis
Pancreatitis in children most commonly presents with nausea, vomiting, and epigastric abdominal pain that may radiate to the back. Additional symptoms include fever, tachycardia, hypotension, and jaundice. Physical examination findings include abdominal distention, hypoactive bowel sounds, and epigastric tenderness, rebound, or guarding. Patients with a pseudocyst may present with abdominal distention and a palpable and tender epigastric mass. Acute hemorrhagic pancreatitis is a rare entity in children and is life threatening when it occurs. These patients may present in shock and have physical examination findings that include a bluish discoloration of the flanks (Grey Turner’s sign) or periumbilical area (Cullen’s sign).
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