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Key Features

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Essentials of Diagnosis
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  • Cystic tumors of liver, lungs, kidneys, bones, brain, and other organs

  • Eosinophilia

  • Urticaria and pruritus if cysts rupture

  • Protoscoleces or daughter cysts in the primary cyst

  • Positive serology

  • Epidemiologic evidence of exposure

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General Considerations
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  • Dogs, cats, and other carnivores are the hosts for Echinococcus granulosus

  • Cystic and alveolar echinococcosis (hydatid disease) cause significant morbidity and mortality worldwide

  • Endemic areas include Australia, New Zealand, and the southwestern United States, including Native American reservations where shepherding is practiced

  • Primary sites of involvement are the liver (60–70%) and the lungs (20–25%)

  • A unilocular cyst is most common

  • Cysts of Echinococcus multilocularis are multilocular and demonstrate more rapid growth

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Clinical Findings

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Symptoms and Signs
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  • Vary and depend primarily on the site, size, and condition of the cysts

  • Growth rates of cysts are variable and range between 1 and 5 cm in diameter per year

  • Liver cysts

    • Can cause hepatomegaly, right upper quadrant pain, nausea, and vomiting

    • If a cyst ruptures, the sudden release of its contents can result in a severe allergic reaction

    • May cause biliary obstruction

    • Most are in the right lobe

  • Rupture of a pulmonary cyst causes

    • Coughing, dyspnea, wheezing, urticaria, chest pain, and hemoptysis

    • Cyst and worm remnants are found in sputum

  • Brain cysts may cause focal neurologic signs and convulsions

  • Renal cysts cause pain and hematuria

  • Bone cysts cause pain

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Differential Diagnosis
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  • Tumors, bacterial or amebic abscess

  • Cavitary tuberculosis (pulmonary)

  • Mycoses

  • Benign cysts

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Diagnosis

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Laboratory Findings
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  • Antibody assays

    • Useful to confirm a presumptive diagnosis

    • However, some patients do not have a detectable immune response (related to the integrity of the cyst and sequestration of echinococcal antigens inside the cyst)

  • Eosinophilia is present in only about 25% of patients

  • Serologic tests are useful for diagnosis and follow-up of therapy

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Imaging
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  • Visualization of daughter cysts is highly suggestive of echinococcosis

  • CT, MRI, and ultrasonography are useful for the diagnosis of deep-seated lesions

  • Abdominal ultrasonography is most widely used diagnostic tool

  • Pulmonary or bone cysts may be visible on plain films

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Diagnostic Procedures
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  • Ultrasonography-guided fine-needle aspiration coupled with parasitologic examination for protoscoleces, rostellar hooks, antigens, or DNA may confirm diagnosis

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Treatment

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Medication
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  • Chemotherapy alone has been shown to cure about one-third of patients

  • Albendazole

    • Should be initiated for several days prior to surgery

    • Dosage: 15 mg/kg/d divided in two doses for 3 months, maximum 400 mg twice daily

    • Praziquantel is sometimes added

  • For alveolar echinococcus, lifetime chemotherapy may be required in some patients (particularly in those in whom complete resection is not possible)

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Surgery
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  • Definitive therapy of E multilocularis...

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