HYDATID DISEASE: SPECTRUM OF ATYPICAL LOCATIONS AND COMPLICATIONS ON IMAGING. A PICTORIAL REVIEW

Hydatid disease, or cystic echinococcosis, is a parasitic zoonosis caused by the larval stage of Echinococcus granulosus and remains endemic in Morocco. Although the liver and lungs account for most cases, the parasite may lodge in any organ or soft tissue, where it mimics a wide range of benign and malignant lesions. This review illustrates the imaging spectrum of hydatid disease in atypical locations and its main complications, and details, organ by organ, the features that distinguish it from its differential diagnoses. Cases of hydatid disease in atypical or complicated locations managed in the Department of Radiology of Hassan II University Hospital, Fez, Morocco, were retrospectively reviewed and complemented by a PubMed and ScienceDirect search. Imaging modalities included ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI). Twenty-one illustrated observations document involvement of the spleen, kidney, pancreas, adrenal gland, peritoneum and retroperitoneum, interventricular septum, diaphragmatic crus, pulmonary artery, brain, spine and spinal cord, soft tissues, testis and ovary, together with biliary rupture, bacterial superinfection, exophytic growth, peritoneal seeding and abdominal wall invasion. Two findings proved discriminating across all sites: the parasitic signs (daughter vesicles, detached membranes, mural calcification and the peripheral T2-hypointense rim) and the absence of enhancement of the cyst contents and septa. Hydatid disease should be included in the differential diagnosis of any cystic lesion, whatever its site, particularly in endemic regions. Familiarity with these appearances helps avoid diagnostic error and potentially life-threatening complications.