Imaging spectrum of hydatid cyst in common and uncommon locations

Hydatid disease, caused by the larval stage of Echinococcus species, continues to be a significant health problem in endemic regions globally. While the liver and lungs are most commonly affected, this parasitic infection can involve virtually any organ, often creating diagnostic dilemmas for radiologists. In our experience at a tertiary referral centre serving an endemic population, we've encountered numerous unusual presentations that prompted this review. Here, we illustrate the broad imaging spectrum of hydatid disease across various anatomical sites, with particular focus on atypical locations. We detail characteristic imaging features on ultrasound, CT, and MRI, highlighting the pathognomonic signs that aid in accurate diagnosis. From the classic spoke-wheel pattern to the less recognised "serpentine sign," familiarity with these imaging patterns is essential for proper management, preventing complications such as anaphylaxis from cyst rupture, and guiding surgical planning. This review aims to refresh radiologists' knowledge of the diverse presentations of hydatid disease in both typical and unusual anatomic locations.