Table 2.

WHO/IWG-E classification of cystic Echinococcosis ¹¹

WHO/IWG-E classification	Image characteristics
CL	Univesicular, cystic lesion with uniform echoes, clear boundary, thin visible wall (Active form)
CE1	Unilocular, simple cysts with uniform anechoic content. A visible cyst wall, hydatid sand and “snow flake sign” corresponding to hydatid sand are pathognomonic signs
CE2	Multivesicular, multiseptated cysts; cysts septations produce “wheel-like”structures, and presence of daughter cysts is indicated by “rosette-like” or “honeycomb-like” structures.
CE3a	Detachment of laminated membrane from the cyst wall visible as “big snake sign” or as “Water-lily sign”. The hydatid status is transitional.
CE3b	Intracystic shadow of the daughter vesicles and solid septation, manifested as complex cyst shadow. The hydatid is dying.
CE4	Heterogeneous degenerative contents with a ball of wool, contain no daughter cysts
CE5	Intracystic solid degeneration and calcification of the cystic wall (inactive stage)

WHO/ IWGE = World Health Organisation/ Informal Working Groups on Echinococcosis