Acute pancreatitis is an inflammatory process with variable involvement of regional tissue, remote organ systems, or both. Various complications of pancreatitis are common, including intra- or extra-pancreatic fluid collections and development of a pancreatic pseudocyst or abscess, or even pancreatic tissue necrosis. Infected necrosis involves diffuse bacterial inflammation of necrotic pancreatic and peripancreatic tissue without significant pus collection. In contrast, a pancreatic abscess is a circumscribed collection of pus, usually in proximity to the pancreas, that is positive for bacteria, bounded by adjacent tissue and organs and has minimal amounts of associated necrosis.
Bacteria may enter inflamed tissue either at the beginning of the episode of acute pancreatitis or during a later phase, depending on the virulence of the microorganism(s) involved and the level of host immune defenses. Microorganisms may be eliminated, or they may propagate freely: if infection proceeds, it can spread, leading to development of infected necrosis, or it may remain localized, resulting in abscess formation.
A 69-year-old man was admitted to West China Hospital (Chengdu, China) with more than two months of abdominal pain and roughly seven days of fever. More than two months previously, he had been diagnosed with severe acute pancreatitis at a local hospital based on a chief complaint of abdominal pain. After about one month of effective and regular treatment, he was referred to our hospital to continue therapy. On admission, the patient had poor nutritional status, variable mental status, and multiple organ system dysfunction. Abdominal computed tomography (CT) revealed severe acute pancreatitis, significant fluid in the peripancreatic region, and pus in the muscle of the lower back (Figure 1). With time, the patient's general condition improved with antibiotic therapy, nutritional support, internal environment amelioration with drainage and associated procedures, and traditional Chinese medicine. About seven days before readmission, the patient's temperature spiked to 38.9°C without development of chills, nausea, vomiting or jaundice. On readmission, edema of both lower extremities was noted, and the following 24-hour urine volume was only about 400 ml. Meanwhile, a supporating wound appeared on the left side of the groin, with pus quickly becoming free flowing (Figure 2). Drainage of his pancreatic abscess was performed through the upper back following internal medical treatment. The patient was discharged in good condition about a month after drainage of his abscess.
Pancreatic abscesses are usually within or in close proximity to the pancreas. In contrast to infected pancreatic necrosis, a pancreatic abscess contains little or no necrosis and typically presents later in the course of the illness, often more than four weeks after onset of acute pancreatitis. Frequently, clinical and laboratory findings of acute pancreatitis have resolved before the pancreatic abscess is detected. Because the infected collection is walled off and the surrounding tissue is viable, spread of infection to adjacent tissues is uncommon.
Pancreatic abscess may be single or multiple, unilocular or multilocular. The abscess may involve the entire gland or be primarily right-sided or left-sided; abscesses may be related to the head of the gland, the body or the pancreatic tail.1 The abscess may extend to the perirenal space, hilum of the spleen, the liver,2 the transverse mesocolon, the retroperitoneal space,3 or even the space of the lesser omentum.4 In our patient, the abscess may have extended through one of two main routes. It could have extended through the mesocolon transversum to the peritoneal cavity and then into the groin, or it could have encroached on the perirenal space along the major psoas muscle and extended to the spatium retroperitoneale, after which it could have invaded the preperitoneal space as it is in communication with the retroperitoneal space. In our case, CT revealed that both of the patient's perirenal spaces, especially on the left side, and the muscle of the lower back were invaded by pus, so we consider the second route be primary.
Moreover, we should study why the abscess was so serious in the patient. When pancreatitis results in necrosis of pancreatic tissue, areas of necrosis are at risk of being infected. The risk of secondary infection appears to be related to the course of acute necrotizing pancreatitis as necrotic tissue is sterile. Later, necrotic tissue may act as a focus for bacterial seeding. In our case, the patient's physical status was so bad when first admitted that his defense capacity was clearly insufficient to prevent infection and later spread. Nutritional support shows clinical promise in preventing infectious complications5 and early enteral nutrition for treatment of acute pancreatitis has been shown to be superior and much more cost-effective than parenteral nutrition.6 In our case, delay of formal therapy and malnutrition probably led to the broad extension of the abscess and its infectious complications. A recent report indicted that aggressive supportive therapy and antibiotic therapy is the main treatment strategy within the acute phase of pancreatitis (first two weeks).7 So when pancreatitis occurs, we should realize the importance of anti-infection therapy, sufficient drainage, and sufficient nutritional support to avoid worsening of any developing abscesses.
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Keywords:© 2010 Chinese Medical Association
pancreatic abscess; groin