Many types of benign and malignant tumors occur in the urinary tract, however in the daily routine the most common ones are oncocytoma and renal cell carcinoma.

Benign renal tumours

Oncocytoma is the most important benign renal tumor. It originates from intercalated cells of the tubules. The name comes from the tumor cells are oncocytes, cells with large eosinophilic cytoplasm due to high content of mitochondria. The tumor is brownish on macroscopy. It can be hard to distinguish from chromophobe RCC, for which we must use cytogenetics.

Angiomyolipoma is a benign hamartoma of the kidney. It’s comprised of blood vessels, smooth muscle and adipose tissue, as the name suggests. It’s more frequent in patients with the systemic disease tuberous sclerosis.

Papillary adenoma is a small (5mm) and greyish benign tumor of the kidney.

Renal cell carcinoma

Renal cancer

Wilms tumour

Wilms tumor or nephroblastoma is the most common malignant renal tumor in children; the average age the patient during diagnosis is 3 years old. It rarely occurs in adults, but it can happen. The tumor is comprised of blastema, the embryological tissue that the normal kidney develops from. This tumor may have primitive glomeruli and tubules.

Wilms tumor is associated with a mutation in the WT1 tumor suppressor, which especially occurs in case of WAGR syndrome.

Urothelial carcinoma can occur in the renal pelvis but it will be discussed in the next topic.