Urine cytology is most useful in screening extraglomerular hematuria for which condition?

• A. Ureteropelvic junction obstruction
• B. Urothelial carcinoma
• C. Renal cell carcinoma
• D. Polycystic kidney disease

Answer: (B)

Urine cytology detects malignant cells shed from the urothelium and is especially useful when hematuria comes from the lining of the urinary tract (extraglomerular hematuria). Urothelial carcinomas arise from the urothelial cells lining the renal pelvis, ureter, bladder, and calyces, so malignant cells are shed into urine and can be seen on cytology. This makes urine cytology the best screening tool among the options for urothelial carcinoma. It’s less helpful for UPJ obstruction or polycystic kidney disease, which are not malignancies shedding urothelial cells, and for renal cell carcinoma, which originates in the renal parenchyma and often does not shed cells into urine.