FROM THE ARCHIVES OF THE AFIP - TRANSITIONAL-CELL CARCINOMA OF THE URINARY-TRACT - RADIOLOGIC-PATHOLOGICAL CORRELATION

The urothelium is a target tissue for carcinogens that lead to the dev elopment of transitional cell carcinomas (TCCs), both synchronous and metachronous. Although there are pathologic and imaging features commo n to transitional cell tumors occurring anywhere in the genitourinary tract, certain findings are more typical of tumors of the renal pelvis , ureter, or urinary bladder. A slightly irregular, fixed mass arising from any urothelial surface is characteristic of TCC. Although such m asses are usually confined to the collecting system lumina, larger les ions that arise in the renal pelvis may extend into the renal parenchy ma, typically in an infiltrative pattern that preserves the reniform s hape. In contrast to the rapidly developing mural edema associated wit h obstructing calculi, the relatively slow growth of ureteral TCC allo ws for gradual expansion of the ureteral lumen around the tumor and is less likely to produce acute renal colic. Focal wall thickening, eith er eccentric or circumferential, may also be a manifestation of TCC of the ureter or, less commonly, other portions of the urinary tract. Th e urinary bladder is the most common site of TCC; lesions are generall y confined to the lumen and typically do nor extend beyond the bladder wall until quite large.