Renal hydatid cyst

Case contributed by Mohammadtaghi Niknejad


Abdominal pain.

Patient Data

Age: 65 years
Gender: Female

A large partially exophytic hetero-signal mass with internal layer detachment was seen in the upper pole of the left kidney. There is no sign of local invasion to adjacent structures. Gallbladder is not seen (prior surgery).
Central intra and extra-hepatic bile ducts are mildly dilated (CBD=11 mm). There is no filling defect at dilated ducts and distal part of CBD shows tapering. Features may consistent with post cholecystectomy changes.


A large partially exophytic mass with internal layer detachment, wall and internal calcification was seen in the upper pole of the left kidney. Additionally, three cysts with smooth and thin walls, sharp and distinct marginations, and a homogeneous water-density were seen in the left kidney. The largest one is 23 mm in diameter.
Gallbladder was not seen (prior surgery). Mild dilatation of extra-hepatic and central intra-hepatic bile ducts was seen. Common bile duct is 12 mm in caliber.

Case Discussion

Features on CT scan and MRI are compatible with left renal hydatid cyst (pathology proved).
CT scan is an accurate and sensitive modality for diagnosis of renal hydatid cyst 1 and shows a unilocular or multilocular cyst with or without peripheral calcification. CT scan may also show a detached membrane, a multiloculated cyst with mixed internal density, and daughter cysts with lower density than the maternal matrix 2.
Hydaturia is a pathognomonic sign of renal hydatidosis 2.

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