Image may be NSFW.
Clik here to view.
In the latest Case Record of the Massachusetts General Hospital, a 25-year-old man was admitted to the hospital because of abdominal pain, syncope, and hypotension that occurred while he was lifting heavy boxes. An abdominal ultrasound examination revealed a hypoechoic lesion in the liver. A diagnostic test was performed.
Rupture or leak of hydatid-cyst fluid due to accidental or surgical trauma or extreme physical activity is a well-documented cause of anaphylaxis. There have been rare cases of anaphylaxis due to spontaneous rupture.
Clinical Pearls
The definitive hosts for E. granulosus are dogs and other canines. Stray dogs often feed on carcasses or offal of slaughtered animals and thus acquire parasites, including cestodes (tapeworms) such as Taenia saginata, T. solium , and four species of echinococcus — Echinococcus granulosus, E. multilocularis, E. vogeli, and E. oligarthrus. These parasites can cause IgE-mediated anaphylaxis. A human becomes the accidental host with the ingestion of infected embryonated eggs shed by stray dogs. The eggs, which contain the infectious oncospheres, penetrate the intestinal wall and enter the bloodstream. Although most oncospheres lodge in the liver and develop into hydatid cysts, such cysts can also occur in the lungs, bones, brain, heart, and muscle.
What are the clinical manifestations of hydatid cysts?
Clinical manifestations of hydatid cysts occur after a highly variable incubation period. The majority of persons with hydatid cysts remain asymptomatic for years, but symptoms related to infection of a cyst occur in approximately 25% of such persons. Occasionally, a hydatid cyst of the liver causes problems such as rupture into the biliary tree, obstruction, fibrosis, and enterocutaneous fistula. Hydatid cysts have also been associated with the development of bacterial infection. In rare cases, a cyst ruptures into the peritoneal cavity and causes anaphylaxis.
Morning Report Questions
Q: When imaging shows a suspected hydatid cyst in the liver, how is the diagnosis of echinococcal infection confirmed?
A: In general, diagnostic aspiration is not routinely recommended in patients with hydatid cysts because of the risk of fluid leakage resulting in an anaphylactic reaction and possible dissemination of the disease. Antibody detection is the most commonly used diagnostic method. Sensitivity and specificity vary among tests, depending on the type of antigen and the stage and location of the disease.
Q: How are hydatid cysts treated?
A: The choice of therapy is guided by the radiographic appearance of the cyst and the patient’s clinical symptoms. Small cysts that have a stable cyst wall and no daughter cysts may require only clinical observation without intervention or may be treated with antihelminthic agents alone, whereas large cysts with multiple septations or daughter cysts typically require invasive intervention. For large cysts (>5 cm in diameter) or those that are complex, patients may undergo surgery (either cystectomy or partial liver resection) or percutaneous aspiration by means of the PAIR (puncture, aspirate, inject, and reaspirate) procedure. The PAIR procedure is performed by inserting a catheter through the germinal layer of the cyst, aspirating the contents, injecting fluid that is lethal to the protoscolices (e.g., ethanol or hypertonic saline), and then repeatedly flushing the cyst. Surgery is favored for cysts with many compartments that may not be amenable to complete evacuation and for very large cysts that cause compressive symptoms; surgery is also favored when cysts are in close proximity to the biliary tree, because the PAIR procedure can result in leakage of cyst contents or scolicidal solution into the biliary system, causing cholangitis.
