Radiological Characteristics of Pulmonary Hydatid Cysts

Hydatid disease is a parasitic infection caused by Echinococcus granulosus (EG), characterized by cystic lesions in the liver, lungs, and rarely in other parts of the body. Lungs and liver are the most frequent sites involved. Simultaneous lung and liver cysts are observed in less than 10% of the cases. Hydatid cysts are found more frequently in the lungs of children and adolescents than in their liver, while most cysts in adults are hepatic and relatively few are in the lungs. The hydatid serology results are often negative in patients with isolated pulmonary hydatidosis, and hence may not be helpful in problematic cases. Radiologic approach to the intact, complicated, or ruptured pulmonary hydatid cysts includes a CT scan following the chest radiograph. Thoracic CT may be supplemented with magnetic resonance (MR) imaging and occasionally with ultrasound (US) in clarifying a pleural-based hydatid cyst as extrapleural, pleural, or parenchymal.