Ultrasonographic classification of cysts due to cystic echinococcosis

(Panel CL) Consists of unilocular, cystic lesion(s) (CL) with uniform anechoic content. The cyst wall is not clearly visible; lesions are usually round but may be oval. If these lesions are caused by cystic echinococcosis at an early stage of development, they are usually not fertile. Definitive diagnosis cannot be made by ultrasound findings alone.
(Panel CE1) Consists of unilocular, simple cyst with uniform anechoic content. The cyst wall is visible; lesions are round or oval. Cyst may exhibit fine echoes due to shifting of brood capsules called hydatid sand ("snow flake sign").
(Panel CE2) Consists of multivesicular, multiseptated cysts. The cyst wall is normally visible; lesions are round or oval. Septations produce "wheel-like" structures. The presence of daughter cysts is indicated by rosette-like or honeycomb-like structures. Daughter cysts may partly or completely fill the unilocular mother cyst.
(Panel CE3) Consists of a unilocular cyst which may contain daughter cysts. Anechoic content with detachment of laminated membrane from the cyst wall may be visible as floating membrane or as "water-lily sign" which is indicative of wavy membranes floating on top of remaining cyst fluid. The cyst form may be less round because of decreased intracystic pressure. The cyst which may degenerate further or may give rise to daughter cysts.
(Panel CE4) Consists of heterogenous hypoechoic or hyperechoic degenerative contents; no daughter cysts are present. A "ball of wool" sign may be seen, which is indicative of degenerating membranes. Most cysts of this type are not fertile. Definitive diagnosis cannot be made by ultrasound findings alone.
(Panel CE5) Cysts characterized by a thick calcified wall that is arch shaped, producing a cone shaped shadow. The degree of calcification varies from partial to complete. These cysts are not fertile in most case. Definitive diagnosis cannot be made by ultrasound findings alone.