A Rare Case of Collecting Duct Carcinoma: A Comprehensive Analysis Using Ultrasound, Computed Tomography, and Histopathological Examination.

Collecting duct renal cell carcinoma (cdRCC) is an exceptionally rare and aggressive subtype of renal cell carcinoma, accounting for approximately 1% of all renal tumors. This case is notable due to the comprehensive use of multi-modality imaging and detailed histopathological examination, offering valuable insights into the diagnostic challenges and management of this rare condition. A 64-year-old male presented with progressive right flank pain, hematuria, and decreased urine output. Imaging studies revealed a hypoechoic lesion in the right kidney, predominantly located in the hilar and perihilar regions, suggestive of a malignant renal tumor. Further diagnostic evaluation, including a right radical nephrectomy, was performed. The histopathological examination of the resected tissue confirmed the diagnosis of cdRCC, characterized by a tubulopapillary growth pattern, significant pleomorphism, and sarcomatoid changes. Immunohistochemical analysis showed strong positivity for epithelial membrane antigen and CK7, confirming the aggressive nature of the tumor. This case underscores the importance of early diagnosis and a comprehensive diagnostic approach to managing cdRCC. Despite advances in imaging techniques, a definitive diagnosis often relies on histopathological and immunohistochemical analysis. The aggressive nature of cdRCC and its generally poor prognosis highlight the need for prompt and accurate diagnosis to potentially improve patient outcomes. This report adds to the limited literature on cdRCC, emphasizing the challenges and considerations in diagnosing and managing this rare form of renal carcinoma.

Collecting duct renal cell carcinoma: a single centre series and review of the literature.

Introduction: Collecting duct, or Bellini duct, renal cell carcinoma (CDRCC) is a rare tumour, comprising only 0.4-2% of all renal cell carcinoma. The goal of this study was to evaluate the cases in our institution and look at current available literature. Material and methods: We searched all data on renal cell tumours in our institution between 2011 and 2021 and identified four cases with confirmed CDRCC pathology. Important features were listed and analysed. We also reviewed current available literature and compared it to our case series. Results: All cases were men with a median age of 63.5 years. All were symptomatic at presentation. Two patients presented with flank pain and two with gross haematuria. Three patients had stage IV disease at time of presentation and one stage III disease. All cases had clear Bellini duct renal cell carcinoma appearance on microscopy with infiltrative tubular architecture and high-grade nuclear features. Immunohistochemic (IHC) staining was performed for diagnostic confirmation. Three patients underwent radical nephrectomy and received adjuvant chemotherapy. One case had kidney biopsy for diagnostic confirmation and received first line chemotherapy. Immunotherapy or tyrosine kinase inhibitor (TKI) were started for second, third or fourth line of treatment. Median overall survival after diagnosis was 11 months. Conclusions: CDRCC is a rare subtype of renal cell carcinoma with poor prognosis, typically presenting in a more advanced or metastatic stage. Diagnosis can be challenging. Multimodality treatment should be considered using radical surgery and systemic treatment.

Identification of a novel cancer stem cell subpopulation that promotes progression of human fatal renal cell carcinoma by single-cell RNA-seq analysis.

Background: Cancer stem cells (CSCs) are biologically characterized by self-renewal, multi-directional differentiation and infinite proliferation, inducing anti-tumor drug resistance and metastasis. In the present study, we attempted to depict the baseline landscape of CSC-mediated biological properties, knowing that it is vital for tumor evolution, anti-tumor drug selection and drug resistance against fatal malignancy. Methods: We performed single-cell RNA sequencing (scRNA-seq) analysis in 15208 cells from a pair of primary and metastatic sites of collecting duct renal cell carcinoma (CDRCC). Cell subpopulations were identified and characterized by t-SNE, RNA velocity, monocle and other computational methods. Statistical analysis of all single-cell sequencing data was performed in R and Python. Results: A CSC population of 1068 cells was identified and characterized, showing excellent differentiation and self-renewal properties. These CSCs positioned as a center of the differentiation process and transformed into CDRCC primary and metastatic cells in spatial and temporal order, and played a pivotal role in promoting the bone destruction process with a positive feedback loop in the bone metastasis microenvironment. In addition, CSC-specific marker genes BIRC5, PTTG1, CENPF and CDKN3 were observed to be correlated with poor prognosis of CDRCC. Finally, we pinpointed that PARP, PIGF, HDAC2, and FGFR inhibitors for effectively targeting CSCs may be the potential therapeutic strategies for CDRCC. Conclusion: The results of the present study may shed new light on the identification of CSCs, and help further understand the mechanism underlying drug resistance, differentiation and metastasis in human CDRCC.

Can Analgesic-abuse Nephropathy is a Fertile Groundfor for Rare Collecting Duct (Bellini Duct) Renal Cell Carcinoma or Merely a Coincidence?

Nonsteroid antiinflammatory drugs have been implicated as nephrotoxic drugs, causing both acute and chronic adverse effects that range from reversible ischemia to chronic kidney disease and urothelial tumors to renal cell carcinoma specially papillary subtype. We report one case of collecting duct (Bellini duct) renal cell carcinoma in patient with analgesic-abuse nephropathy. This young individual was suffering from ankylosing spondylitis since the age of 16 years and was consuming diclofenac and paracetamol (acetaminophen) combination for >15 years. He developed hypertension, secondary glomerulopathy, chronic kidney disease and collecting duct renal cell carcinoma.