Bosniak cyst - type IV

Case contributed by Ian Bickle


Complex left renal cyst on ultrasound. CT to assess.

Patient Data

Age: 55 years
Gender: Male

Complex enhancing mass at the lower pole of the left kidney, with a necrotic center.


The full Bosniak classification

Case Discussion

Exophytic part solid-part cystic lesion in the lower pole of the left kidney.  The solid components enhance.

The appearances are those of a type IV Bosniak cyst, 100% of which are malignant.

Image guided renal biopsy was performed.  It was a renal cell carcinoma.

The patient declined treatment.

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