Presentation
Long-standing history of nephrolithiasis and periodic gross hematuria.
Patient Data
In the mid-pole of the left kidney, a 28 mm mass with heterodyne content and areas of cystic components is seen. After IV contrast media, enhancement is noted in the solid components on PVP images that show relative washout on delayed phase images.
There are three stones less than 4 mm in the right renal calyces. In addition, a 16 mm stone in the left renal pelvis along with mild hydronephrosis.
Case Discussion
The patient went to have a nephron-saving left renal mass resection, and histopathology evaluation confirmed a renal cell carcinoma, clear cell subtype.
Approximately 15% of solid renal cell carcinomas can contain cystic elements. Furthermore, central necrosis often occurs in large renal cell carcinomas. These characteristics can resemble a Bosniak class IV cystic renal mass.
Per the Bosniak classification 2019, if the enhancing solid component volume of a renal cystic lesion exceeds 25% of total mass volume, the Bosniak classification is not applicable. The mass should be classified as a solid renal mass with cystic/necrotic changes. This is because a solid renal cell carcinoma with cystic/necrotic changes carries a worse prognosis than a renal cell carcinoma originating from a Bosniak class IV cystic renal mass.
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