| A 73-year-old man presented to the Urology Department complaining of pain in the left renal fossa and hematuria. | |
| The ultrasound study showed a cystic renal lesion with variable echogenicity at the parietal level that measured 17 cm of maximum diameter. | |
| The clinical suspicion of renal cell carcinoma with cystic degeneration was surgically intervened and the nephrectomy specimen was sent to our Service. | |
| It was a cystic ovoid formation of 1500 g and 18 x 16 x 6.5 cm, whose external surface was homogeneous with a brownish-red colored colored colored tone highlighting certain focal areas of color | |
| Cutting showed a bilocular cystic cavity occupied by abundant friable material of hemorrhagic aspect. | |
| The wall thickness ranged from 0.3 to 0.6 cm. Contact multiple areas of calcification as well as a peripheral renal helmet in one of the poles of 7 cm. in the sinus of which there was a cystic white lesion. | |
| The renal pelvis was compressed by the described lesion. | |
| The hiliar vessels and the ureteral stump showed no evident macroscopic alterations. | |
| Microscopic examination revealed a lesion consisting of tubules well formed in aposion filled by sigmoid cells with central nucleus hyperchromia not covering atypia or mitosis, sometimes protuding tubular lumen. | |
| The lesion was cystic, finding remnants and large number of hemosiderin-loaded macrophages at this level. | |
| Focal parietal calcification and intense peripheral fibrosis as pseudocapsules were observed in the remaining renal structures free of significant histological alterations. | |