Echinococcosis is a disease caused by the parasites called tapeworms belonging to the Echinococcus genus. Humans get infected by ingesting the parasite eggs in contaminated water, food, or soil, and through having direct contact with the animal hosts.
The clinical presentation of cystic echinococcosis (CE) is extremely variable. Humans stay asymptomatic for a long period of time after being infected, as the cysts usually grow slowly. The presenting features depend on the number of cysts, size, and the mass effect on the organ and surrounding tissues.
Potential manifestations leading to the diagnosis of CE are the mechanical effect a cyst has on its adjacent tissues with obstruction of the biliary tree while embolism and acute hypersensitivity reactions due to a cyst rupture or leakage with anaphylaxis can also occur. However, such a cyst is usually asymptomatic and found accidentally during surgery, radiographic examination or evaluation for other conditions.
Liver cysts should be included in the differential diagnoses of jaundice, portal hypertension, ascites and colicky pain. They may be misdiagnosed as alveolar echinococcosis, hematomas, amebic or pyogenic liver abscess, metastases, adenoma, hepatocellular carcinoma, textiloma, and lymphoma  .
Alveolar echinococcosis (AE) results from infection with Echinococcus multilocularis in its larval stage. It is rare but potentially life-threatening  . The incubation period can last from five to fifteen years. During the initial phase, patients are typically asymptomatic. The first symptoms which arise are cholestatic jaundice and upper abdominal pain .
Chest pain, dyspnea, cough, and hemoptysis are the symptoms that may lead to the incidental detection of lung involvement. The lungs can be affected by means of hematogenous dissemination or invasion through the diaphragm  .
Ultrasound is the imaging modality of choice when diagnosing asymptomatic CE. It is non-invasive, safe, and relatively cost-effective.
The World Health Organization Informal Working Group on Echinococcosis (WHO-IWGE) suggested standard ultrasound classification based on the status of the cyst (active, transitional, or inactive) which depends on the sonographic appearance .
Ultrasound is not able to differentiate all the hydatid cysts from other lesions like liver abscesses and tumors. So, additional imaging studies like computed tomography (CT) and magnetic resonance imaging (MRI) are required. MRI is preferred as it provides better visualization of the liquid areas in the matrix than CT scans . It also helps in the evaluation of CE prior to surgical intervention.
Immunodiagnosis can be used as a confirmation tool after a radiologic diagnosis has been made. It is also useful in the pharmacological and post-surgical follow-up of patients even though an immune response may not be detected in all of them   .
The diagnosis of AE remains a challenge in spite of technical advances and resources. With this delay, management starts at a later stage, limiting the available treatment options. AE is characterized by a tumor-like growth which may infiltrate the surrounding structures . Early detection can increase the rates of curative surgical resection .
Radiologic studies play a major role in diagnosing AE but histopathologic evaluation and PCR can confirm it. For several years, X-rays, ultrasound and other imaging methods such as CT scans and MRI have been used for diagnosing, managing, and following up cases of AE .