Case Study: Incidental low grade invasive transitional cell carcinoma of minor calyx in a hydronephrotic kidney with renal stones


Incidental carcinoma of the renal pelvis is a rather common radiological finding with hydronephrotic kidneys or kidneys with renal stones; but it is extremely rare to detect carcinoma of the renal pelvis in such cases. I have recently reported one such case. So clinicians, radiologists, and pathologists should be aware of the fact that incidental carcinoma in a hydronephrotic kidney not only involves the renal pelvis but also the calyxes, and they should take measures accordingly!


The majority of the hydronephrotic kidneys are examined for tumors around the pelvis and the ureters, and meticulous examination of whole pelvi-calyceal system is not done; thus we might have missed possible tumors. Here we shall discuss the diagnostic possibility of infiltrative urothelial carcinoma when a large, nonfunctioning, hydronephrotic kidney is present.

Case Presentation

A 43-year-old female patient presented with recurrent urinary tract infections, hematuria, edema and renal colic. Imaging (ultrasonography and CT-scan) detected the hydronephrosis (sac-like dilatation) of the left kidney. Surgical removal of the non-functioning kidney was performed. Gross finding was a sac-like dilated kidney with 4 small (2-3 mm) blackish stones in the minor calyceal system and a grayish-white exophytic growth measuring 3 x 2 x 2 cm. Histopathological examination confirmed the infiltrative low grade urothelial cancer. The patient recovered fully 15 days after the operation without any complications.

Investigationscell carcinoma histology pic. 1

  • Urine chemical and microscopic examination
  • Urine microbiology
  • USG and CT-scan
  • Blood test for urea and creatinine
  • Serology and pre-anesthetic check-up

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Differential Diagnosiscell carcinoma histology pic. 2

Tubular ectasia, small pelvicaliceal calculi, tuberculosis, leukoplakia, cholesteatoma, multiple stricture-like lesions of the pelvicaliceal system, caliceal amputation, or calcification.

Clinical and radiological studies might suggest the above possibilities. Histopathological examination rules out other possibilities and confirms the final diagnosis.


The following treatments were performed:

  • Control of recurrent urinary tract infections
  • Surgical removal of the non-functioning kidney (nephrectomy)

Outcome and Follow-Up

The patient recovered fully 15 days after the operation without any complications and is doing well 3 months after surgery.


Transitional cell carcinoma of the renal pelvis, accounting for only 7% of all kidney tumors, and transitional cell cancer of the ureter, accounting for only 1 of every 25 upper tract tumors, are curable in more than 90% of patients if they are superficial and confined to the renal pelvis or ureters. Differentiation of focal renal infections with or without caliceal obstruction from infiltrative TCC that has infiltrated overlying parenchyma may be problematic because imaging findings overlap. Invasive TCC is suspected when an infiltrative hypovascular mass coexists with a filling defect in the adjacent collecting system or amputation of a calyx. Large infiltrative TCCs with both pelvic and parenchymal involvement may simulate other entities such as lymphoma, metastasis, xanthogranulomatous pyelonephritis, or RCC with invasion into the renal pelvis.

In TCC of the renal pelvis, intratumoral or superficial calcifications are present in 2%–7% of cases. These calcifications may be punctate, linear, or granular. Although the appearance could be confused with that of tubular ectasia, small pelvicaliceal calculi, tuberculosis, leukoplakia, and cholesteatoma, the finding of an invasive mucosal lesion strongly suggests the possibility of TCC. Although this entity is uncommon, failure to recognize its occurrence may result in a delayed or erroneous diagnosis.

However, renal tuberculosis may sometimes be difficult to differentiate from pelvicaliceal malignancies because it may mimic renal TCC, particularly when it appears as multiple stricture-like lesions of the pelvicaliceal system, caliceal amputation, or calcification.

Learning Points/Take Home Messages

In patients with long-standing hydronephrotic kidneys, scrutinize meticulously for incidental cancer.

About The Author

Dr. Samanta, MBBS, MD is currently a consultant at Suraksha diagnostic PVT. LTD. Kolkata, India for histopath, cytopath and hematology. His other interests are: oncopathology, bone marrow and neuropathology.

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