Bosniak radiological approach to renal cysts

Q: Bosniak classification of kidney cysts is done via? (select one)

A) intravenous (IV) contrast-enhanced computed tomography (CT)

B) ultrasonography (US)

C) magnetic resonance imaging (MRI)

D) level of pain

Answer: A

The biggest challenge in evaluating kidney cysts is differentiating between simple and complex cysts, mainly when the cyst size is > 1 cm. Bosniak kidney cyst classification helps diagnose and manage complex cysts. It requires a CT scan of the kidneys with IV contrast. It is named after Dr. Bosniak.

US or MRI should be used when the cyst size is less than 1 cm. Cysts are classified into five categories in ascending order of complexity: Category I, II, IIF*, III, and IV.

                                                  

The more complex the cyst, the higher the chances of malignancy.

                                                  

In the 2019 version, the Bosniak classification was updated.

#nephrology

#radiology

* F is for staging on follow-up

References:

1. Bosniak MA. The current radiological approach to renal cysts. Radiology 1986; 158:1.

2. Israel GM, Bosniak MA. An update of the Bosniak renal cyst classification system. Urology 2005; 66:484.

3. Curry NS, Cochran ST, Bissada NK. Cystic renal masses: accurate Bosniak classification requires adequate renal CT. AJR Am J Roentgenol 2000; 175:339.

4. Harisinghani MG, Maher MM, Gervais DA, et al. Incidence of malignancy in complex cystic renal masses (Bosniak category III): should imaging-guided biopsy precede surgery? AJR Am J Roentgenol 2003; 180:755.

5. Silverman SG, Pedrosa I, Ellis JH, et al. Bosniak Classification of Cystic Renal Masses, Version 2019: An Update Proposal and Needs Assessment. Radiology 2019; 292:475.