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Cystic Echinococcus - Tania Kupferman PGY-3

posted Dec 16, 2014, 8:08 AM by Kevin Hauck

This week on CRS we solved the case of a 35 year-old man from Peru, who presented to the hospital with stabbing, unremitting right-upper quadrant pain that had started acutely a few hours earlier after he received a blow to the area while playing soccer (i.e., real football).On ROS, he did not have fever or chills, no weight loss and endorsed some nausea and vomiting which occurred after the accident on the field. He had no pleuritic pain and no dyspnea.He had no known past medical history, no prior surgeries, and took no medications. He did not use tobacco or illicit drugs, he consumed occasional alcohol; he was in a monogamous relationship with his wife.

Our initial differential diagnosis took into account the on location and onset of pain and was actually quite broad. We considered injury to the liver/gallbladder as very likely, followed by pancreatitis (from trauma), rib fracture, splenic rupture, and the future cardiologists in the room suggested we considered a possible MI.We also began to think that in this young man, the injury most likely unmasked an underlying problem which had previously gone undetected. We thought of hepatic angiomas, AV malformations, or abscesses that may have ruptured.

On further history, we learned that he had immigrated to the US about 10 years prior to his current presentation. He had no known medical problems in his family. And that he had been a farmed in his native Peru.

At this point we expanded on the possibility of abscess from some infectious etiology that still not clear to us. Some pathogens were thrown around the table but we were not ready to commit, especially since most of there were hard to pronounce.

His physical exam was remarkable for tachycardia with normotension. He was afebrile. There was no erythema at the site of injury and no visible ecchymoses. He had normal heart and lung exams. There was tenderness to deep palpation over the RUQ but there was no rebound or guarding. There was no jaundice and no other stigmata of chronic liver disease.

The exam has helpful in narrowing our differential by focusing our attention to deep structures of the right-upper quadrant. At this point, we thought musculoskeletal injury was unlikely, and there was no reason to continue to suspect a pneumothorax or other lung pathology.

His blood work was significant for hemoglobin ~12g/dL, platelets near 450K/uL, and WBC ~7.6K/uL with about 36% neutrophils and 24% eosinophils. His BNP was unremarkable, as were coagulation tests, and cardiac markers. Liver tests showed a AST/ALT in the 60’s range and an alk phos of 150U/L. Total protein, albumin, and bilirubin levels were all normal.

The high eosinophil count immediately caught our attention and we started to seriously think about the “worms” that our patient was at risk for given his country of origin and past exposures. Some of the pathogens that were brought up included amoeba, ascaris, echinococcus,

We were instead presented with the results of a CT scan with contrast which revealed a very large, heterogenous hypodensity inside the liver. There were no solid masses and no evidence of an intrahepatic bleed.

Although not so obvious to us initially, the finding of a cyst-like mass in a person with a history of exposure to sheepdogs in an area where E. granulosus is endemic, suggests a diagnosis of cystic echinococcosis. While we did eventually come up with the correct diagnosis—a ruptured echinococcus cyst, secondary to trauma—it was not before we ourselves were diagnosed with ‘knowledgeopenia’ by Dr Lefrancois.

To remedy that, here’s a brief review:

Cystic echinococcosis (aka hydatidosis) is a zoonotic disease that results from infection with the larval stage of Echinococcus granulosus, a cestode found in dogs (definitive host), sheep, cattle, goats, foxes, and pigs (intermediate hosts). People become infected by swallowing tapeworm eggs which can be found in the feces and fur of infected animals.

Echinococcus is endemic to Africa, Europe, Central Asia, the Middle East, and Central and South America, with the highest prevalence in populations that raise sheep. In North America, E. granulosus has been reported in Canada and Alaska, whereas in the United States most infections are diagnosed in immigrants from countries where the disease is endemic. In endemic regions, incidence rates for cystic echinococcosis can reach <50 per 100 000 person-years, with a prevalence as high as 5–10% in parts of Argentina, Peru, east Africa, central Asia, and China.

Most infections in humans are asymptomatic for a number of years, but can present with slowly enlarging masses, most commonly in the liver and the lungs. Pain or discomfort in the upper abdomen, nausea, vomiting, or cough as a result of the growing cysts. Cases can also present after rupture of a cyst which can lead to a severe allergic reaction. Larval metastases may spread to organs adjacent to the liver or to distant locations (lungs, brain) through dissemination of the parasite via the blood and lymphatic system. Diagnosis is often suspected by history and imaging as described above. Specific antibodies can be detected by serological tests and can support diagnosis. Biopsies and ultrasound-guided punctures may also be performed.

Echinococcosis infection can be complicated to treat, frequently requiring surgery in addition to prolonged antimicrobial therapy. Drug therapy alone with albendazole is appropriate for single-compartment cysts, that are <5cm in diameter. Praziquantel is sometimes used in addition to albendazole, although there is no clear evidence regarding its efficacy.

Surgery is the treatment of choice for management of complicated, multi-loculated or very large cysts; it must be extensive and usually followed by anti-infective prophylaxis to minimize the risk of secondary infection through seeding. Some countries favor the use of percutaneous aspiration, injection of chemicals and re-aspiration techniques in place of surgery. A small clinical trial suggested that outcomes among patients undergoing percutaneous drainage with albendazole were comparable to those undergoing surgery alone.

Bear in mind that echinococcosis can relapse years after treatment and monitoring is recommended although the exact modality and duration for this are not specified.

Tania Kupferman

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