Right Renal Pelvis Renal Cell Carcinoma Mimicking Transitional Cell Carcinoma: Case Report (2024)

Abstract

Keywords: RCC, TCC, ureteroscopy, nephroureterectomy, nephrectomy

Introduction

The renal pelvis is lined with transitional epithelium; it has a mucous membrane and is covered with transitional epithelium with imbedded layer of lamina propria of loose connective tissue.¹ There are multiple types of tumors that affect the renal pelvis, including renal cell carcinoma (RCC), transitional cell carcinoma (TCC), medullary carcinoma, angiomyolipoma, and oncocytoma. Although renal pelvis TCC is relatively rare in terms of urologic malignancies (5%), it is the most common tumor originating in the renal pelvis (90%).¹ RCC and metastatic tumors such as colon cancer can also rarely occur in the renal pelvis and can manifest in CT or MRI as renal pelvis masses simulating TCC. For this reason, it has been suggested that imaging should not be used exclusively to diagnose TCC.¹ Preoperative ureteroscopy with biopsy, retrograde pyelogram, and urine cytology are common preoperative procedures to determine type of tumor, grade, and stage to determine surgery type and need for chemotherapy.² This case report provides an example of RCC growing in renal pelvis simulating TCC and uses our experience to make potential suggestions to better confirm the diagnosis.

Case Report

A 75-year-old woman presented to emergency department in October 2019 with gross hematuria. Denied fever or weight loss. She has a history of hypertension and 37 pack-year smoking history quitting 30 years prior. Family history is nonpertinent. Physical examination was nonpertinent. She had a known history of a 6.4 cm Bosniak 2F right renal cystic mass extending toward the renal sinus followed with serial MRIs for the past 5 years and stable. An MRI urogram was performed revealing no filling defects and stable cyst. Cystoscopy and cytology were negative, and hematuria resolved spontaneously.

In March 2020, she represented with gross hematuria with dysuria and right flank pain. No change in medical history, medications, or review of systems except for aforementioned. Laboratories showed hemoglobin of 11.6 g/dL, glomerular filtration rate (GFR) >60, and renal and liver function tests all within normal range. Urinalysis was significant for moderate blood and urine culture was negative. A CT urogram revealed a new 2.5 cm right renal pelvis solid mass not seen in MRI 5 months prior as seen in Figure 1A and B.

April 2020, a retrograde pyelogram showed a circumferential filling defect in renal pelvis, seen in Figure 2A. Flexible ureteroscopy was performed, a 2.5 cm mass identified in right renal pelvis. Lesion appeared as a well-circ*mscribed lesion with fibrinous exudate. Superficial and deep biopsies from the tumor were taken and the tissue appeared friable and vascular as in Figure 2B and C. Pathology report revealed acellular necrotic tissue superficially and granulation tissue in deep tissue, cannot rule out TCC. Urine cytology confirmed abundant clusters of urothelial cell with cytologic atypia. Secondary to recurrent hematuria, smoking history, location, retrograde findings, and pathology report there was a high suspicion for TCC. Patient was offered surgical removal vs neoadjuvant chemotherapy and elected for surgery.

In May 2020, uncomplicated robot-assisted laparoscopic right nephroureterectomy with partial cystectomy was performed. Length of stay 1 day, Foley catheter was removed 7 days postsurgery no complications, postoperative creatinine 0.88; GFR 64.

Final pathology report revealed a 2.5 cm RCC, clear cell variant, Fuhrman nuclear grade 2, T3a, N0, M0 with invasion to the renal pelvis. All margins negative as seen in Figure 3.

Discussion

This case reported a challenging diagnosis of a right renal pelvis mass. RCC originating in renal pelvis is a rare type of carcinoma with few reports in literature. In 1990, Munechika and colleagues¹ reported a calcified tumor in the lower pole of the right kidney extending to the renal pelvis and ureter. CT study confirmed the presence of a renal pelvic mass without evidence of involvement the renal sinus.¹ It has been shown that CT urography has limitation of false-positive diagnosis.¹ Secondary to this and the need to grade and stage the tumor preoperative it has been suggested that ureteroscopy-guided biopsies can better evaluate renal pelvis tumors. In our case CT and retrograde supported the diagnosis of TCC; however, pathology analysis and urine cytology were concerning for TCC but inconclusive. Many factors could have played a role of why we had inconclusive results, including not enough samples for pathologist, atypical histology report of samples submitted for pathology analysis, and low sensitivity of urine cytology in diagnosing TCC, especially in patients with low-grade disease. The aforementioned case brings up specific questions: (1) How accurate and effective are biopsies and urine cytology in diagnosing TCC vs RCC? (2) In patients where TCC is not confirmed, could an intraoperative pathology evaluation have prevented ureterectomy and partial cystectomy?

The accuracy of ureteroscopic biopsy of renal pelvis tumors has been previously studied. A meta-analysis published by Subiela and colleagues² in the European Journal of Surgical Oncology in July 2020 studied 23 studies with 3547 patients. A comparison between ureteroscopic biopsy and final pathology report was performed for upper urothelial carcinomas to predict stage and grade. Positive predictive value for T1+ disease was 94% and negative predictive value Ta/Tis was 60%. Grade-to-grade match between ureteroscopic biopsy and final pathology report was 66% and 97% for low-grade and high-grade disease, respectively, indicating a moderate to strong correlation between biopsy and final pathology report. However, the undergrading and understaging rates were 32% and 46%, respectively, placing a risk that should be taken into account.²

In terms of the effectiveness of urine cytology in diagnosing urinary tract neoplasms, there is limited literature on urine cytology of TCC of the upper urinary tract. Voided urine has 70% to 75% sensitivity in diagnosing TCC making it a challenge to diagnose based on urine cytology.³ To diagnose TCC, cytology must demonstrate numerous clusters of cells with nuclear irregularity with pleomorphism, hyperchromasia, increased nucleus/cytoplasm ratio, and nuclear overlap. In a study conducted by Bier, 385 upper tract samples were studied. Sensitivity of urine cytology was 74%. Detection of urothelial carcinoma can be improved using urine sample markers such as fluorescence in situ hybridization, NMP22, and uCyt+. Sensitivities can reach 100% with use of NMP22.³ Clear cell type RCC microscopic findings include variable mixtures of cystic and branched tubular components with clear cytoplasm and nuclei aligned away from basem*nt membrane.³ Although not reported, this potentially could be mistaken for suspicious for high-grade TCC.

Without a definitive preoperative diagnosis of TCC, another option is sending the renal mass for pathologic evaluation after the removal of the kidney; obtain a frozen section before proceeding with ureterectomy and partial cystectomy. In a study at Baylor University, 125 intraoperative consultations for urologic frozen specimens were studied, 17 radical nephrectomy specimens were submitted with 6 involving the hilum and collecting system with primary suspicion of RCC but cannot clinically rule out TCC. Fourteen specimens confirmed RCC, none of the submitted specimens, including the hilar tumors, showed TCC. In addition, 9 nephroureterectomy specimens with primary suspicion of TCC were submitted, all of them confirmed TCC.⁴ In situations where a renal pelvic tumor is present for which TCC is suspected but not officially diagnosed, nephrectomy with a portion of the ureter can be performed with intraoperative frozen section to confirm diagnosis. If TCC is confirmed, the rest of the ureter with bladder cuff can be removed.

This report shines a spotlight on the importance of preoperative evaluations for tumors within the renal pelvis. There are some steps that could have been done differently that would have changed the management of this case. In addition to imaging, ureteroscopic biopsy and cytology can be used. Sensitivities can be amplified with the use of other biomarkers, including NMP22. When extirpation is warranted and preoperative diagnosis is still uncertain, we could have used intraoperative frozen section to avoid unnecessary procedures and risks to the patient.

Conclusion

In this study, uncommon case of RCC growing within in the renal pelvis was presented. This case illustrates how imaging alone may be insufficient to differentiate RCC and TCC. The roles of ureteroscopy and multiple deep biopsies with urine cytology and biomarkers are emphasized to have a better evaluation of the nature of the tumor and to decide management; especially the surgery performed to remove it. It is also stressed based on our study to consider the role of intraoperative frozen samples to confirm the diagnosis in cases of unconfirmed clinical suspicion.

Abbreviations Used

Disclosure Statement

No competing financial interests exist.

Funding Information

No funding was received for this article.

Cite this article as: Sheckley F, Nobert C, Stifelman M (2020) Right renal pelvis renal cell carcinoma mimicking transitional cell carcinoma: case report, Journal of Endourology Case Reports 6:4, 536–539, DOI: 10.1089/cren.2020.0180.

References