Cystic Lesions of the Renal Sinus

Peripelvic Cysts

• multiple benign cysts arising in the renal sinus (extraparenchymal)
• likely originate from sinus lymphatics
• usually bilateral
• may mimic hydronephrosis on US and NCECT but cannot be traced to the ureter
• indistinguishable from renal sinus lipomatosis on excretory urography

Parapelvic Cysts

• simple cysts originating from the medial renal parenchyma
• same imaging features as simple renal cysts (Bosniak I)
• usually asymptomatic but a large parapelvic cyst that compresses the renal vasculature/collecting system may cause hypertension, hematuria, and hydronephrosis

REFERENCES

Rha SE, Byun JY, Jung SE, et al. The renal sinus: pathologic spectrum and multimodality imaging approach. Radiographics 2004;24:S117-31.