The purpose of this pictorial essay is to illustrate the radiologic findings (US, CT, MR) of abdominal hydatidic cyst disease with emphasis on pitfalls, diagnostic difficulties and differential diagnosis. We havereviewed the sonographic, CT, and MRI features of extrahepatic hydatid disease,; including visceral, intraperitoneal, retroperitoneal and hematogenous spread. This review should allow us to get familiar with atypical manifestations and complications of hydatid disease that may be helpful in making an accurate and prompt diagnosis.

Hydatid disease is the larval cystic stage of Echinococcus granulosus infection, that can cause illness in intermediate hosts; generally herbivorous animals and humans who are infected accidentally. Clinical features of cystic echinococcosis are highly variable. The spectrum of symptoms depends on the involved organs, the size of cysts, the interaction between the expanding cysts and the adjacent organs and finally the disseminated spread of the disease. The classical findings in hydatid disease are well known; however, findings related to disease complications and unusual anatomic locations...

RADIOLOGICAL FINDINGS Hydatid disease primarily affects the liver and typically demonstrates characteristic imaging findingsdependingon the stage of cyst growth (whether the cyst is unilocular, multilocular containing daughter vesicles, or ifpartiallyor completely calcified [dead]). In radiologic studies the typical findings of hydatid disease are well known, but unusual imaging characteristics related with its rare complications are less frequently documented in the literature. It is expected that a complicated hydatid cyst is associated with higher morbidity and mortality. Therefore, familiarity with atypical radiological features is very important...

Hydatid disease primarily affects the liver and typically demonstrates well-knowncharacteristic imaging and serological findings. However,it should be kept in mind that hydatid cysts can causemany potential local complications and secondary extrahepatic involvement thatmay be seen indifferentanatomic locations presenting asunusual US, CT and/or MRI findings. The major teaching point of this exhibit is to learn the different appearances of abdominal hydatid disease and to understand the main complications and atypical manifestations in order to be able to recognize themand make a prompt accurate diagnosis and treatment.

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