Imaging analysis of 13 rare cases of renal collecting (Bellini) duct carcinoma in northern China: a case series and literature review

Urothelial Carcinoma of the Renal Pelvis with Synchronous Ipsilateral Collecting Duct Carcinoma: Two Case Reports

Synchronous renal malignancies are seldom encountered or diagnosed post-renal resection. A combination of renal cell carcinoma (RCC) and urothelial carcinoma (UC) is most commonly reported. Typically, the RCC subtype is clear-cell RCC; however, a combination of collecting duct carcinoma (CDC) and UC has rarely been reported in the existing literature. Here, we present two cases of synchronous renal malignancy, specifically a combination of CDC and UC, in the ipsilateral kidney.

A Rare Case of Collecting Duct Carcinoma With Extensive Coagulative Necrosis

Collecting duct carcinoma (CDC) is an aggressive renal malignancy with limited diagnostic and therapeutic consensus. We report a case of a 69-year-old male with CDC and extensive coagulative necrosis who presented with lower extremity swelling, abdominal distention, and an enlarged left kidney causing grade IV hydronephrosis. Initial treatment with a left percutaneous nephrostomy was followed by clinical deterioration and a diagnosis of emphysematous pyelonephritis. Pathological examination of drainage material revealed extensive coagulative necrosis and was suggestive of a necrotic neoplasm. Subsequent left nephrectomy confirmed CDC with high-grade features, stromal desmoplasia, and extensive coagulative necrosis. Immunohistochemistry studies supported the diagnosis. This study highlights the diagnostic complexity of CDC and emphasizes the need for accurate reporting of atypical presentations. CDC remains a formidable clinical entity with limited treatment options and poor outcomes. Further research is essential to enhance our understanding and management of this rare and aggressive renal malignancy.

Collecting duct carcinoma with retroperitoneal mass as initial presentation: a rare case report

BACKGROUND

Collecting duct carcinoma (CDC) is a rare renal tumor, originating from the distal collecting duct. CDC rarely presents as a primary tumor outside the renal system.

CASE PRESENTATION

In this study, we report a rare case of collecting duct carcinoma, with an initial presentation of retroperitoneal lymph node metastasis, and no identifiable primary renal tumor on CT, at the time of diagnosis. The patient was a 64-year-old man presenting with lower back pain. Preoperative CT showed a round, soft tissue mass, measuring 6.7 × 4.4 × 3.3 cm, in the left retroperitoneum with no exact occupying lesion in the left kidney. Clinically, ectopic pheochromocytoma was considered to be a differential diagnosis, and tumor resection was performed. Postoperative pathological results demonstrated that the mass was a fused lymph node, and the tumor cells were destroying the structure. The final diagnosis was lymph node metastatic collecting duct carcinoma, by histology and immunohistochemistry. No further treatment was performed as no space occupying lesion was found in the kidney. Three months later, CT was reexamined, and a mass of 3.6 cm in diameter, was found in the lower left kidney, along with multiple soft tissue masses, in the left renal hilum. Considering recurrence or metastasis, the patient was recommended to undergo surgical treatment, but the patient refused. Four months later, CT was re-examined. The tumor had rapidly progressed but the patient refused treatment again. As per the author's press release (eleven months after the first discovery), the patient is still alive.

CONCLUSION

CDC is a rare malignant renal carcinoma, with a high chance of rapid progress, regional lymph nodes involvement and metastasis. It presents diagnostic challenges to clinicians and pathologists, particularly, in the absence of radiographically detectable intrarenal lesions. Definite diagnosis is based on pathological examination combined with immunohistochemical staining.

Collecting Duct Carcinoma of the Kidney: A Single-Center Retrospective Study of 23 Cases

Objective: To explore the clinical, imaging, pathologic features, treatment, and prognostic outcomes in 23 cases of collecting duct carcinoma (CDC) from a single center. Methods: The clinical and imaging findings, pathological features, treatment methods, and outcomes of the 23 patients with CDC confirmed by microscopic examination between 2003 and 2020 at our institution were retrospectively reviewed. Descriptive statistics of demographic and clinical variables were applied. Kaplan-Meier method was used to analyze survival data and log-rank test statistic survival differences between groups. Cox regression analysis was employed to identify variables independently related to overall survival (OS). Results: A total of 23 patients with CDC were identified. The mean age was 50.8 years. Stage III or IV tumors were diagnosed in 82.6% of the patients at diagnosis. The average size of the tumor was 6.58 cm, and the left kidney was more involved than the right. The median OS was 12 months. The OS rates at 1 and 2 years were 43.5% and 26.1%, respectively. Twenty patients underwent nephrectomy, 3 underwent nephroureterectomy, and 9 (39.1%) patients received subsequent therapeutic interventions following surgery. Distant metastasis and no symptoms at initial diagnosis proved to be an independent factor of unfavorable survival in Cox regression analysis. Conclusions: CDC is a rare and highly aggressive malignant renal tumor, and most patients present at an advanced stage at initial diagnosis. More than half of the patients died within 1 year after surgery. Distant metastasis and no clinical symptoms at initial diagnosis were independent risk prognostic factors for patients with CDC.

Update in collecting duct carcinoma: Current aspects of the clinical and molecular characterization of an orphan disease

Collecting duct renal cell carcinoma (cdRCC), which until recently was thought to arise from the collecting ducts of Bellini in the renal medulla, is a rare and aggressive type of non-clear renal cell carcinoma (ncRCC), accounting for 1% of all renal tumors and with nearly 50% of patients being diagnosed with Stage IV disease. The median overall survival in this setting is less than 12 months. Several regimens of chemotherapies had been used based on morphologic and cytogenetic similarities with urothelial cell carcinoma described previously, although the prognosis still remains poor. The use of targeted therapies also did not result in favorable outcomes. Recent works using NGS have highlighted genomic alterations in SETD2, CDKN2A, SMARCB1, and NF2. Moreover, transcriptomic studies have confirmed the differences between urothelial carcinoma and cdRCC, the possible true origin of this disease in the distal convoluted tubule (DCT), differentiating from other RCC (e.g., clear cell and papillary) that derive from the proximal convoluted tubule (PCT), and enrichment in immune cells that may harbor insights in novel treatment strategies with immunotherapy and target agents. In this review, we update the current aspects of the clinical, molecular characterization, and new targeted therapeutic options for Collecting duct carcinoma and highlight the future perspectives of treatment in this setting.

Incidence, Clinical Characteristics, and Survival of Collecting Duct Carcinoma of the Kidney: A Population-Based Study

Objective

To investigate the exact age‐adjusted incidence (AAI), clinical characteristics, and survival data of collecting duct carcinoma of the kidney (CDCK) recorded in the Surveillance, Epidemiology, and End Results (SEER) database of the National Cancer Institute.

Methods

Patients with CDCK confirmed by microscopic examination from 2004 to 2018 were selected from the SEER database. AAI rates were calculated using SEER*Stat software (version 8.3.9). The Kaplan‐Meier method was used to evaluate cancer-specific survival (CSS) rates according to tumor size, tumor stage, and treatment methods, and differences among these variables were assessed by the log‐rank test. Cox regression analysis was employed to identify variables independently related to CSS.

Results

A total of 286 patients with CDCK were identified from the database. The majority of the patients were white (69.2%), male (67.5%), and married (60.5%), and the median age was 59 years. Most patients with CDCK (74.4%) presented with stages III or IV disease. The diameter of most (59.4%) tumors was less than 7 cm, and the tumors were more commonly found on the left than on the right (55.2% vs. 44.8%). The incidence of CDCK decreased over time. The median CSS time was 17 months. In terms of the treatment modalities used, 83.9% of the patients underwent surgery; 32.9% underwent chemotherapy, and 13.6% underwent radiotherapy. The CSS rates at 1, 2, and 5 years were 57.3%, 43.2%, and 30.7%, respectively. In patients with stage IV CDCK treated with surgery alone, chemotherapy alone, and surgery plus chemotherapy, the median survival time was 5 months, 9 months, and 14 months, respectively (P =0.024). Multivariate Cox regression analysis showed surgery, chemotherapy, stage, regional lymph node metastasis, and distant metastasis were independent prognostic factors for patients with CDCK.

Conclusions

CDCK is an uncommon malignant renal carcinoma, and its incidence is decreasing based on the analysis of current data. CDCK is a high stage, regional lymph-nodes positive, and metastatic disease. Compared with surgery alone or chemotherapy alone, patients with stage IV could gain survival benefit from surgery combined with chemotherapy.