CYST

Solitary cyst: 

• A well rounded, echo-free mass with acoustic enhancement, usually less than 3 cm in diameter. is likely to be a solitary simple congenital cyst. 
• A small hydatid cyst must also be excluded.
  Solitary cyst with a rough irregular outline-liver abscess.
  
  
  

MULTIPLE CYST

Multiple cystic lesions:
Multiple spherical cystic masses of varying sizes, completely echo-free with a sharp outline and posterior acoustic enhancement, may indicate congenital ploycystic disease.
 Search for cysts in the kidney, pacreas and spleen: congenital cystic disease can be very difficult to differentiate from hydatid disease.
Complex cyst:
 Hemorrhage or infection of any cyst may result in internal echoes and resemble an abscess or necrotic tumour.

HYDATID DISEASES

• Simple cysts containing no internal architecture except sand.
• Cysts with detached endo-cyst secondary to rupture , 
•  Cysts with detached cysts ,matrix (echogenic material between the daughter cysts) or both.
   Densely calcified masses.