Hydatid Disease: A Radiological Pictorial Review of a Great Neoplasms Mimicker

Abstract

Hydatid cyst is a common name for the larval stage of a tapeworm species of the genus Echinococcus granulosus, which is transmitted from animals to humans via the fecal–oral route. Hydatid cysts predominantly affect the liver (75%), followed by the lung (15%), and they can affect many organs in the human body. Medical imaging modalities are the keystone for the diagnosis of hydatid cysts with high sensitivity and specificity. Ultrasound imaging with high resolution is the first choice for diagnosis, differential diagnosis, staging, establishing a role in interventional management, and follow-up, and it can differentiate Type I hydatid cysts from simple liver cysts. Unenhanced computed tomography (CT) is indicated where or when an ultrasound is unsatisfactory, such as with chest or brain hydatid cysts, when detecting calcification, and in obese patients. Magnetic resonance imaging (MRI) is superior for demonstrating cyst wall defects, biliary communication, neural involvement, and differentiating hydatid cysts from simple cysts using diffusion-weighted imaging (DWI) sequences. According to the phase of growth, hydatid cysts occur in different sizes and shapes, which may mimic benign or malignant neoplasms and may create diagnostic challenges in some cases. Hydatid cysts can mimic simple cysts, choledochal cysts, Caroli’s disease, or mesenchymal hamartomas of the liver. They can mimic lung cystic lesions, mycetoma, blood clots, Rasmussen aneurysms, and even lung carcinomas. Differential diagnosis can be difficult for arachnoid cysts, porencephalic cysts, pyogenic abscesses, and even cystic tumors of the brain, and can create diagnostic dilemmas in the musculoskeletal system.

Management of liver hydatid cyst: A case report

“…Daughter cysts appear hypoattenuating with a honeycomb appearance and multiple internal septations representing walls of daughter cysts, reflecting Type II hydatid disease 6 . A total calcification reflects the dead cysts and is hyperattenuating on a CT scan 5,6 . We did an urgent computed tomography scan of the abdomen and pelvis (Figure 1).…”

“…However, ultrasonography is less sensitive in detecting small cysts and compression effects due to enlarged liver 1 . A computed tomography (CT) scan of the abdomen and pelvis should be used for definitive diagnosis 2,3,5 . CT scan is more sensitive to detect calcification, small cysts, internal septa, daughter vesicles, and hepatomegaly's compression effects 6 .…”

Posterior Mediastinal Hydatid Cyst with Spine and Chest Wall Involvement

“…Depending on the organ affected and the stage of the disease, different symptoms may be present. 1 , 2 …”

“…Additionally, magnetic resonance imaging (MRI) is used, which is superior for displaying cyst wall, contents, and nearby neural involvement. 2 …”

“…In that situation, incorporating MRI with diffusion-weighted imaging (DWI) sequences and ultrasound with high resolution imaging (when the location is accessible for scanning) helps us further characterize the cyst and its contents and distinguish HC from other different cystic lesions that have occurred in that specific organ. 2 , 3 …”