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Abdomen » Kidneys/Ureters
Urothelial tumor of the right renal pelvis
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Presentation A 67 year old male, smoker, presented for right flank pain and urgency. The family history revealed a brother deceased secondary to a renal tumor. Blood tests showed increased activated partial thromboplastin time (aPTT), international normalized ratio (INR) and fibrinogen. Abdominal ultrasound was performed to assess the renal and prostatic morphology.
 
 
 
Caption: Right kidney, transverse section at the hilum.
Description: A moderately echogenic parenchymal mass appears on the right renal medial margin. The mass appears to be located outside the kidney.
 
 
 
Caption: Right kidney at hilum. Color Doppler examination.
Description: The parenchymal mass presents dot-like vessels in the periphery.
 
 
 
Caption: CT, nonenhanced
Description: Axial scan through the mid portion of the right kidney. An isodense parenchymal mass of 4.4cm/2.4cm, is seen in the inferior half of right renal hilum.
 
 
 
Caption: CT, postcontrast
Description: Axial scan through the mid portion of the right kidney. A mass surrounded by fluid density is seen inside the renal pelvis.
 
 
 
Caption: CT, late postcontrast.
Description: Axial scan through the mid portion of the right kidney. A slight dilatation of right renal pelvis and a hypodense mass in the inferior part of the contrast filled pelvis are apparent on this sequence.
 
 
 
Caption: Macroscopic and microscopic pathology images.
Description: Left: macroscopic image of the urothelial tumor Right: - microscopic hystopatology of the tumor - low grade urothelial cell papillary carcinoma.
 
Differential Diagnosis Urothelial tumor of the pelvis – suggested by the appearance and location of the mass, although there was no dilatation
Renal adenocarcinoma – solid mass with some vascularity, but unlikely due to the location of the mass
Right renal pelvic clot – unlikely due to internal vascularity and lack of history for hematuria
Right renal pelvic pus debris or fungus ball - unlikely due to internal vascularity and lack of suggestive clinical findings
 
Final Diagnosis Non-obstructive urothelial cell tumor of the right renal pelvis
 
Discussion The ultrasound study disclosed a parenchymal mass measuring 4.7cm by 1.4cm, localized in the right renal hilum. The mass was located outside the renal sinus, below the renal vascular pedicle. There was no hydronephrosis and no abnormal lymph nodes were seen in the renal hilum. (ultrasound image 1). The renal vein and the inferior vena cava were patent on Doppler ultrasound. Dot-like vessels appeared at the periphery of the mass on color Doppler. (ultrasound image 2). The shape and position of the mass did not change during real time scanning. The left kidney was normal. The prostate gland was enlarged.

Upper tract urothelial tumors of the renal pelvis and ureters are relatively rare. Tumors of the renal pelvis account for approximately 10% of all renal tumors and approximately 5% of all urothelial tumors. Transitional cell carcinoma (TCC) accounts for more than 90% of upper tract urothelial tumors. The mean age of occurence is 65 years, but the incidence of TCC increases with age. Upper tract urothelial tumors occur more frequenrtly in men, with a male-to-female ratio of 3:1. [1] Among the etiological factors are: tobacco smoking; analgesic and coffee abuse; occupational exposure to petrochemical, plastic and tar industries; chronic infections; renal calculi; heredity; association with Lynch syndrome II; Cyclophosphamide treatment.[3] Histopathologically, more than 90% are transitional cell carcinoma (associated with smoking), less than 15% are squamous cell carcinoma (frequently associated with infected staghorn calculi) and less than 1% are adenocarcinoma (associated with calculi and long-term obstruction). This type of tumor more frequently involves the renal pelvis (58%), ureter (35%), the renal pelvis and ureter (7%) or are bilateral (2-5%). [1] The most frequent clinical sign is hematuria. Other signs are: flank pain, dysuria, weight loss, anorexia or bone pain. Our patient presented only with right flank pain. 

Transitional tumors spread in a cranio-caudal direction, along the ureters. Lymph node (most commonly the paraaortic, paracaval, ipsilateral common iliac and pelvic groups) and hematogenous (liver, lung, bone) metastasis may also occur. Intravenous pyelography shows in approximately 50-75% of patients as an  irregular radiolucent filling defect in continuity with the wall of the collecting system. Up to 30% of patients may present with obstruction or nonvisualization of the collecting system. In our case the intravenous pyelography showed pyelocaliceal dilatation. [1]

Frequently, asymptomatic, small renal tumors are discovered by ultrasonography. Urothelial tumors appear surrounded by urine, except for the area of origin. Their outline is irregular and the tumor is hypoechoic compared to the renal parenchyma. They are uncompressible and their appearance doesn’t change with the patient’s position. Reportedly, these tumors exhibit poor vascularization at Doppler examination. [5] In our case, the ultrasonographic appearance was unusual: a rather large extrarenal mass, localized in the pelvic area, that was not accompanied by hydronephrosis, although this was present on IVP. This discrepancy may be explained by the diuretic effect of the contrast media used in IVP. In our case, the vascular signal present within the tumor allowed for differentiation from a blood clot. The ultrasonographic diagnosis was confirmed by other examinations and at surgery.

On CT, urothelial cell tumors appear as an irregular filling defect, hypovascularized in comparison with the rest of the kidney, with minimal increase in density after intravenous contrast injection. CT is helpful in tumor staging. [1]
The treatment is, usually, surgical. The surgical standard treatment options are nephroureterectomy with cuff of bladder or segmental resection of ureter, only if the tumor is superficial and located in the distal third of the ureter. Prognosis depends on staging. Median survival for patients with tumors confined to the subepithelial connective tissue was 19.1 months compared to 12.9 months for patients with tumors invading the muscularis. [2, 4]
 
Case References 1. David F Jarrard, Michael N Wilkin, David F Jarrard. Urothelial Tumors of the Renal Pelvis and Ureters. eMedicine Journal, January 1 2002, Volume 3, Number 1.
2. Huben RP, Mounzer AM, Murphy GP: Tumor grade and stage as prognostic variables in upper tract urothelial tumors. Cancer 62(9): 2016-2020,1988.
3. Jensen OM, Knudsen JB, McLaughlin JK: The Copenhagen case-control study of renal pelvis and ureter cancer: role of smoking and occupational exposures. Int J Cancer 1988 Apr 15; 41(4): 557-61.
4. Messing EM, Catalona W.: Urothelial tumors of the urinary tract. In: Walsh PC, Retik AB, Vaughan ED, et al., eds.: Campbell`s Urology. 7th ed., Philadelphia: W. B. Saunders, 1998.
5. Badea R. I., Dudea S. M.,. Mircea P. A, Stamatian F.: Tratat de Ultrasonografie clinicã. Editura Medicalã Bucureºti. Vol. I. 2000, p. 474-479.
 
Technical Details Images were obtained using the following equipment:
- Medison Sonoace 8800 MT scanner with 3.5-5 MHz convex transducer
- SeleCT Series Picker spiral computed tomograph.
 
Follow Up Intravenous pyelography showed a filling defect in the lower part of the right renal pelvis, with slight pelvic dilatation. The spiral CT scan revealed: - an isodense parenchymal mass of 4.4cm/2.4cm, in the inferior half of right renal hilum; (image 3) - postcontrast, there was enhancement in a limited area of the mass, in an early, arterial phase. At a slightly later time, a clearly enhancing, 3.6cm/2cm mass was seen inside the pelvis, surrounded by fluid density. (image 4). In the late phase, slight dilatation of right renal pelvis became obvious and a hypodense mass was seen in the inferior part of the contrast filled pelvis. The mass did not produce any obstruction of the uretero-pelvic junction. (image 5). The CT appearance was considered consistent with non-obstructive right renal pelvic tumor. Laparopscopic nephroureterectomy was performed, with a favourable post-operatve evolution. At pathology, the diagnosis was: low grade urothelial cell papillary carcinoma. (image 6).
 
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