Collecting duct carcinoma of the kidney: are imaging findings suggestive of the diagnosis?

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.

CT and MRI findings of cystic renal cell carcinoma: comparison with cystic collecting duct carcinoma

BACKGROUND

Cystic renal cell carcinoma (CRCC) and cystic collecting duct carcinoma (CCDC) share similar oncogeni and some imaging findings. The aim of this study was to characterize the clinical and CT imagings features of CRCC and CCDC.

METHODS

Thirty-three patients with CRCC and thirteen patients with CCDC with pathologically proven were retrospectively studied. Tumor characteristics were assessed.

RESULTS

On CT imaging, 33 patients(100 %) with CRCC and 13 patients(100 %) with CCDC, tumors calcifications (8 vs. 9, P < 0.0001), had a clear boundary (capsule sign, 30 vs. 2, P < 0.0001), infiltrative appearance (1 vs. 13, P < 0.0001), exogenous appearance (29 vs. 3, P < 0.0001), invaded the renal pelvis or ureter (1 vs. 10, P < 0.0001), hemorrhage (1 vs. 10, P < 0.0001), had retroperitoneal lymph node or distant metastasis (2 vs. 10, P < 0.0001), thickened enhancing internal septations (31 vs. 2, P < 0.0001), and mural soft-tissue nodules (21 vs. 1, P < 0.0001). On MR imaging,13 patients(39 %) with CRCC and 4 patients(31 %) with CCDC, all CRCCs appeared hypointense on T1-weighted images and hyperintense on T2-weighted images, however, all CCDCs appeared hypointense on T1-weighted images and hypointense on T2-weighted images(P < 0.0001). 33 patients with CRCC, they were all alive from3 years to 10 years follow-up, however, 13 patients with CCDC, of which 11 patients were able to be followed up, and 9 patients expired within 5 years of the initial diagnosis and the others are currently still alive.

CONCLUSIONS

Distinguishing features of CRCC and CCDC included calcifications, capsule signs, infiltrative appearance, metastasis, internal septations, mural nodules and signal on CT or MR images. These imaging features may help in differentiating the two renal tumor types.

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

Background

Collecting (Bellini) duct carcinoma (CDC) is a highly malignant and rare kidney tumor. We report our 12-year experience with CDC and the results of a retrospective analysis of patients and tumor characteristics, clinical manifestations, and imaging features by computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET)/CT.

Methods

Retrospective examination of tumors between January 2007 and December 2019 identified 13 cases of CDC from three medical centers in northern China. All 13 patients underwent CT scan, among which eight underwent dynamic enhanced CT scan, two underwent PET/CT scan, and one underwent magnetic resonance cholangiopancreatography (MRCP) examination. The lesions were divided into nephritis type and mass type according to the morphology of the tumors.

Results

The study group included ten men and three women with an average age of 64.23 ± 10.74 years. The clinical manifestations were gross hematuria, flank pain, and waist discomfort. The mean tumor size was 8.48 ± 2.48 cm. Of the 13 cases, six (46.2%) were cortical-medullary involved type and seven (53.8%) were cortex–medullary–pelvis involved type. Eleven (84.6%) cases were nephritis type and two (15.4%) were mass type. The lesions appeared solid or complex solid and cystic on CT and MRI. The parenchymal area of the tumors showed isodensity or slightly higher density on unenhanced CT scan in the 13 cases. PET/CT in two cases showed increased radioactivity intake. Evidence of intra-abdominal metastatic disease was present on CT in nine (69.2%) cases.

Conclusions

The imaging characteristics of CDC differ from those of other renal cell carcinomas. In renal tumors located in the junction zone of the renal cortex and medulla that show unclear borders, slight enhancement, and metastases in the early stage, a diagnosis of CDC needs to be considered. PET/CT provides crucial information for the diagnosis of CDC, as well as for designing treatment strategies including surgery.

Infiltrative Renal Malignancies: Imaging Features, Prognostic Implications, and Mimics

Infiltrative renal malignancies are a subset of renal masses that are morphologically characterized by a poorly defined interface with the renal parenchyma. Infiltrative renal malignancies are less common but more aggressive than more typical renal malignancies and carry an overall worse prognosis. Although an infiltrative renal process often represents a malignant neoplasm, infiltrative masses include a wide spectrum of diseases including primary renal cortical, medullary, and pelvic tumors; lymphoproliferative processes; metastases; and various infectious, inflammatory, immune-mediated, and vascular mimics. The imaging features of these masses are often nonspecific, but with the appropriate history, laboratory results, and clinical context, the radiologist can help narrow the diagnosis and guide further treatment. An invited commentary by Lee is available online.Online supplemental material is available for this article. ^©RSNA, 2021.

Collecting ducts carcinoma: An orphan disease. Literature overview and future perspectives

Collecting ducts carcinoma (CDC) is a rare and aggressive histological subtype of renal cancer accounting for only 1% of renal tumors. Usually patients present in bad clinical conditions due to a symptomatic disease with synchronous metastasis. Due to the rarity of CDC, data from prospective trials evaluating the best treatment for these patients are limited. The prognosis is poor with a median overall survival of around 11 months for patients with metastatic disease. The best treatment option today is considered a doublet chemotherapy with platinum salt plus gemcitabine as a result from a prospective phase II trial, but survival outcomes remain unsatisfactory. The interest in the in-depth understanding the biology of this orphan disease is growing, leading to find potential new biological-driven treatment approaches. Here we review the up-to-date literature evidences to address the best management of this rare and unfavorable clinical condition.

A Renal Cancer with Intermediate Characteristics between Collecting (Bellini) Duct Carcinoma and Urothelial Carcinoma: Case Report and Review of the Literature

Collecting duct carcinoma of the kidney is a rare and aggressive neoplasm of the distal collecting tube, often metastatic at the time of the diagnosis, for which there is no established therapy. We herein describe the case of a 65-year-old man with a renal cancer with a particular immunohistochemical pattern and pathologic aspect. The lesion was diagnosed as a tumor borderline between a urothelial carcinoma with intraductal spreading and a collecting duct carcinoma with caly-ceal and pelvic spreading. The patient is disease-free 11 months after diagnosis, after radical surgery with adjuvant chemotherapy (carboplatine and gemcitabine) and radiotherapy of a local recurrence. Owing to the common embryologic origin of collecting duct and transitional urothelial cells, several authors have reported an association between collecting duct carcinoma and urothelial cancer. The literature is reviewed to evaluate drugs active against urothelial cancer (like ifosfamide, paclitaxel, carboplatin and gemcitabine). This field should be investigated in the future, in the framework of a neoadjuvant or adjuvant chemotherapy able to support radical surgery for local and advanced collecting duct carcinoma.

Uncommon malignant renal tumors and atypical presentation of common ones: a guide for radiologists

OBJECTIVE

While the typical imaging features of the more common RCC subtypes have previously been described, they can at times have unusual, but distinguishing features. Rarer renal tumors span a broad range of imaging features, but they may also have characteristic presentations. We review the key imaging features of atypical presentations of malignant renal tumors and uncommon malignant renal tumors.

CONCLUSION

Renal tumors have many different presentation patterns, but knowledge of the distinguishing MR and CT features can help identify both atypical presentation of common malignancies and uncommon renal tumors.

Bilateral kidneys involvement of collecting duct carcinoma with cystic change: A case report

RATIONALE

Collecting duct carcinoma (CDC) is a rare neoplasm arising from the collecting duct and should be distinguished from other renal cell carcinomas that mostly originated from the proximal tubular epithelium and tumors originated from the urothelium. It usually occurs in unilateral kidney, sometimes found with cystic change.

PATIENT CONCERNS

We present the case of a 53-year-old male suffering from repeated bilateral flank pain for 6 months, increased pain with dysuria for 5 days.

DIAGNOSIS

Ultrasound showed 2 similar hybrid echo masses in bilateral kidneys with enlarged lymph nodes surrounded, which accords with magnetic resonance imaging (MRI), and intraoperative biopsy reported malignancy.

INTERVENTIONS

An exploratory operation was performed and the mass on the left kidney was removed, but pathological result reported collecting duct carcinoma according to the morphological features and immunohistochemical tests. Also postsurgery positron emission tomography-computed tomography (PET-CT) confirmed the mass on the left kidney is also a lesion of CDC.

OUTCOMES

The patient refused chemotherapy and had an overall survival of 7 months.

LESSONS

We presented a case of CDC involving bilateral kidneys with cystic change; this is the first case of bilateral renal occurrence with cystic change to our knowledge. Because of CDC's rapid growth and the lack of effective adjuvant treatment after surgery, the prognosis is poor and the diagnosis should be made carefully.

Aggressive co-existence: Collecting duct and clear cell carcinoma in the same kidney

As in every organ, synchronous multiple cancers are rarely encountered in kidneys. In the literature, mostly co-existence of renal cell carcinoma and transitional cell carcinoma was reported. In the literature, the co-existence of collecting duct carcinoma and clear cell carcinoma was described only for a few cases with different patterns. With these two cases, we aimed to present a very rare entity with synchronous existence of clear cell renal cell carcinoma and collecting duct carcinoma in the same kidneys.

Magnetic resonance imaging (MRI) of the renal sinus

This article presents methods to improve MR imaging approach of disorders of the renal sinus which are relatively uncommon and can be technically challenging. Multi-planar Single-shot T2-weighted (T2W) Fast Spin-Echo sequences are recommended to optimally assess anatomic relations of disease. Multi-planar 3D-T1W Gradient Recalled Echo imaging before and after Gadolinium administration depicts the presence and type of enhancement and relation to arterial, venous, and collecting system structures. To improve urographic phase MRI, concentrated Gadolinium in the collecting systems should be diluted. Diffusion-Weighted Imaging (DWI) should be performed before Gadolinium administration to minimize T2* effects. Renal sinus cysts are common but can occasionally be confused for dilated collecting system or calyceal diverticula, with the latter communicating with the collecting system and filling on urographic phase imaging. Vascular lesions (e.g., aneurysm, fistulas) may mimic cystic (or solid) lesions on non-enhanced MRI but can be suspected by noting similar signal intensity to the blood pool and diagnosis can be confirmed with MR angiogram/venogram. Multilocular cystic nephroma commonly extends to the renal sinus, however, to date are indistinguishable from cystic renal cell carcinoma (RCC). Solid hilar tumors are most commonly RCC and urothelial cell carcinoma (UCC). Hilar RCC are heterogeneous, hypervascular with epicenter in the renal cortex compared to UCC which are centered in the collecting system, homogeneously hypovascular, and show profound restricted diffusion. Diagnosis of renal sinus invasion in RCC is critically important as it is the most common imaging cause of pre-operative under-staging of disease. Fat is a normal component of the renal sinus; however, amount of sinus fat correlates with cardiovascular disease and is also seen in lipomatosis. Fat-containing hilar lesions include lipomas, angiomyolipomas, and less commonly other tumors which engulf sinus fat. Mesenchymal hilar tumors are rare. MR imaging diagnosis is generally not possible, although anatomic relations should be described to guide diagnosis by percutaneous biopsy or surgery.

Huge mucinous tubular and spindle cell carcinoma of kidney: A rare case report and literature review

RATIONALE

Mucinous tubular and spindle cell carcinoma (MTSCC) is a variant of renal cell carcinoma newly added to the WHO classification in 2004. It is a rare variant of renal cell carcinoma and sometimes it is not easy to distinguish MTSCC from papillary renal cell carcinoma, chromophobe renal cell cancer, etc. The prognosis of MTSCC is favorable after surgical resection.

PATIENT CONCERNS

A 45-year-old male patient presented with a right renal mass that was detected on ultrasonography incidentally. The computed tomography scan showed a huge homogenous mass with patchy calcification in the central area, and the lesion was slightly enhanced after contrast injection.

DIAGNOSES

According to postoperative pathology, the patient was diagnosed with MTSCC.

INTERVENTIONS

The patient underwent an open transabdominal radical resection of right kidney and right retroperitoneal lymph node dissection.

OUTCOMES

The surgical outcomes were good, and no recurrence or metastasis was observed during the follow-up.

LESSONS

MTSCC is a rare malignancy of the kidney and the prognosis is usually favorable. Preoperative enhanced CT and MRI can help differentiate MTSCC from other renal tumors, so as to provide a more suitable surgical approach for those who need to retain renal function as much as possible.

Sarcomatoid Renal Cell Carcinoma and Collecting Duct Carcinoma: Discrimination From Common Renal Cell Carcinoma Subtypes and Benign RCC Mimics on Multiphasic MDCT

RATIONALE AND OBJECTIVES

To investigate whether imaging features on multiphasic multidetector computed tomography (MDCT) can help discriminate sarcomatoid renal cell carcinoma (RCC) and collecting duct carcinoma (CDC) from other solid renal masses.

MATERIALS AND METHODS

With institutional review board approval for this HIPAA-compliant study, we derived a cohort of 7 sarcomatoid RCCs, 4 CDCs, 165 clear cell RCCs, 56 papillary RCCs, 22 chromophobe RCCs, 49 oncocytomas, and 16 lipid-poor angiomyolipomas with preoperative multiphasic MDCT with up to four phases (unenhanced, corticomedullary, nephrographic, and excretory). Each lesion was reviewed for contour, spread pattern, pattern of enhancement, neovascularity, and calcification.

RESULTS

Sarcomatoid RCCs and CDCs were more likely than other solid renal masses to have an irregular contour (64% vs 2%, P < 0.001) and an infiltrative spread pattern, defined as infiltration into adjacent renal parenchyma, collecting system, or neighboring structures (82% vs 7%, P < 0.001). When used to discriminate sarcomatoid RCC and CDC from other solid renal masses, an infiltrative spread pattern had a specificity of 93% (287/308) and sensitivity of 82% (9/11), and an irregular contour had a specificity of 98% (303/308) and sensitivity of 64% (7/11).

CONCLUSIONS

Solid renal lesions with an irregular contour or an infiltrative spread pattern are suspicious for sarcomatoid RCC or CDC.

Correlating Preoperative Imaging with Histologic Subtypes of Renal Cell Carcinoma and Common Mimickers

Renal cell carcinoma (RCC) consists of distinct subtypes that have unique pathologic and imaging features as well as specific cytogenetic and molecular characteristics. As the prognosis and therapeutic strategies may differ for each subtype, correlation of the preoperative imaging with the pathologic findings is of great clinical relevance. In addition, differentiation of RCC from benign entities is ideal in order to prevent overtreatment. However, a noninvasive diagnosis with imaging alone is not always straightforward due to the overlapping appearance of RCC with benign lesions such as fat-poor angiomyolipoma and oncocytoma. With new imaging modalities, there have been significant improvements in correlating preoperative imaging with pathologic characteristics. These new discoveries are able to aid in a more specific, noninvasive, diagnosis that in turn helps direct patient management.

The spectrum of renal cell carcinoma in adults

The spectrum of renal cell carcinoma (RCC) includes many neoplasms with distinct cytogenetics, biologic behaviors, and imaging appearances. The advent of molecular therapies targeting different tumor types, new insights into the relative roles of biopsy and surveillance for small incidental tumors, and a growing array of nephron-sparing interventions have altered management of RCC. Similarly, the role of the radiologist is changing, and it is becoming increasingly important for radiologists to familiarize themselves with the various types of RCC. This article introduces the reader to the common and uncommon recognized types of renal cell carcinoma and discusses how these neoplasms differ in imaging appearance and behavior.

Bellini's duct carcinoma: A report of two cases and a review of the literature

Bellini's duct carcinoma (BDC) is a rare and aggressive variant of renal cell carcinoma that possesses an extremely poor prognosis. The greater the grade or stage of disease, the poorer the prognosis tends to be. This study presents two cases of BDC; one case of low grade BDC and one case of high grade BDC in a 47-year-old male and 74-year-old female, respectively. The 47-year-old male patient presented with painless gross hematuria, which had lasted for 3 weeks and subsequently underwent purely laparoscopic nephroureterectomy. After 4-years of follow-up, the patient remained disease-free. By contrast, a right renal tumor was identified in the 74-year-old female patient during a routine examination. Radical right nephrectomy and lymph node dissection were performed, however, 10 months after surgery the patient succumbed due to wide-spread metastasis. The two cases reported in the present study not only represent excellent examples of the disease spectrum, but also act as a reminder of the possibility of detecting BDC in an early stage of disease. Therefore, the epidemiology of BDC has been discussed, and the aggressive growth pattern of BDC has been presented in terms of signs, symptoms and imaging examinations, including ultrasonography, computed tomography (CT), angiography and single photon emission CT, in the early stage of disease.

Multidetector CT imaging features of invasive renal parenchyma urothelial carcinoma

OBJECTIVE

To characterize the multidetector CT imaging features of invasive renal parenchyma urothelial carcinoma (IRPUC).

METHODS

29 patients with IRPUC were retrospectively evaluated. Tumour location, density, cystic or solid appearance, calcification, capsule sign, enhancement pattern and metastases were assessed.

RESULTS

IRPUC involved the right kidney in 82.7% of patients. Medullary involvement was observed in 93.1% of patients. In 89.6% of patients, the reniform contour of the kidney was preserved. Tumours showed an infiltrative appearance (100%) with a poorly defined margin (100%), but an expansile component was also present (20.7%). Linear calcification was present (20.7%). Evidence of intra-abdominal metastatic disease (in 37.9% of cases) and regional lymphadenopathy (in 27.5% of cases) was present. Tumour attenuation was less or equal compared with the renal cortex or medulla on unenhanced CT (p-value> 0.05), after i.v. contrast administration; 100% were of homogeneous low attenuation compared with the normal renal cortex and medulla (p-value< 0.05).

CONCLUSION

IRPUC tends to be more prevalent in the right kidney, poorly defined margin, medullary involvement, with homogeneous enhancement less than the cortex and medulla in all phases.

ADVANCES IN KNOWLEDGE

IRPUC was more prevalent in the right kidney. IRPUC enhancement was less than that of the cortex and medulla on all phases. IRPUC showed poorly defined margin with medullary involvement and preserved reniform contour.

Comparative study of CT appearances in mucinous tubular and spindle cell carcinoma and collecting duct carcinoma of the kidney

OBJECTIVE

To characterize the multidetector CT (MDCT) imaging characteristics of mucinous tubular and spindle cell carcinoma (MTSCC) and collecting duct carcinoma (CDC) of the kidney.

METHODS

21 patients with MTSCC and 18 patients with CDC were studied retrospectively. MDCT was undertaken to investigate differences in tumour characteristics.

RESULTS

Five patients with MTSCC had calcifications as did nine patients with CDC (p = 0.108). In three patients with MTSCC and four patients with CDC, the tumours had a clear boundary (p = 0.682). No patient with MTSCC had retroperitoneal lymph node metastasis as did five patients with CDC (p = 0.015). 16 patients with MTSCC showed homogeneous enhancement, whereas 11 patients with CDC showed heterogeneous enhancement (p = 0.025). The attenuation value of CDC tumours was greater than that of MTSCC and normal renal parenchyma on an unenhanced CT (p = 0.027). MTSCC and CDC tumour enhancement was less than the normal renal cortex and medulla in all phases (p < 0.001). Tumour enhancement was greater for CDC than that for MTSCC in all phases (p = 0.011, p = 0.006 and p = 0.052).

CONCLUSION

Unenhanced and dynamic MDCT may aid in diagnosis and differentiation of MTSCC and CDC of the kidney.

ADVANCES IN KNOWLEDGE

This is the first series evaluating the imaging findings of MTSCC and CDC of which we are aware, and identification of such findings may improve diagnosis of these two rare tumours.

Imaging findings of renal cell carcinoma

There are many imaging modalities used in the diagnosis of renal cell carcinoma, the most common cancer of the kidney, which accounts for approximately 2-3% of adult malignancies. Early detection of this tumor with the correct diagnostic approach using various cross-sectional imaging is very important, as are the clinical and laboratory findings. Familiarity with the spectrum of imaging findings of renal cell carcinoma will enable clinicians to consider appropriate treatment for patients and eliminate unnecessary further imaging studies.

Collecting duct carcinoma of the kidney: Imaging observations of a rare tumor

Collecting duct carcinoma (CDC) is a rare type of renal neoplasm. Early diagnosis is possibly the only factor leading to a prolonged survival for patients with CDC. The purpose of the present study was to characterize the imaging features of CDC and improve its diagnosis. Radiological data of six patients were retrospectively reviewed by three experienced radiologists, including six cases examined with non-contrast computed tomography (CT) scans, five with contrast-enhanced CT scans, one with magnetic resonance urography, one with renal dynamic imaging and two with conventional whole-body ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT scans. All patients were pathologically confirmed with CDC. In total, seven tumors were detected in the six cases, with a mean size of 5.3 cm. Of the tumors, two were solid and the rest were complex solid and cystic. In addition, six tumors were located in medullary areas and only one tumor was found in the cortical location. Cystic components were observed in five tumors. Weak enhancements were observed in all six tumors examined with contrast-enhanced CT, and heterogeneous enhancements were also observed in the majority of these tumors with the exception of one tumor. Infiltrative growth and expansible growth were found in five and two tumors, respectively. Metastatic lesions were detected in all six patients. On MR urography, the involved kidney exhibited similar imaging observations to the CT scan. Renal dynamic imaging revealed a decreased renal function in the involved kidney and an increased renal function in the contralateral kidney. On PET/CT imaging, a marked uptake of ¹⁸F-FDG was found in primary and metastatic lesions. The results of the present study indicated that medullary location, weak and heterogeneous enhancement, infiltrative growth, damage of renal function in the involved kidney and a marked uptake of ¹⁸F-FDG are imaging observations commonly identified in patients with CDC. When a renal tumor exhibits these imaging features, CDC may be suggested as a valuable differential diagnosis.

Renal carcinomas associated with Xp11.2 translocations/TFE3 gene fusions: findings on MRI and computed tomography imaging

PURPOSE

To retrospectively analyze MRI and computed tomographic (CT) findings from renal carcinomas associated with Xp11.2 translocations/TFE3 gene fusions (Xp11-RCC).

MATERIALS AND METHODS

Institutional review board permission was obtained to review patient medical records, and the requirement for informed consent was waved . The clinical and MRI/CT features of five cases with Xp11-RCC that were confirmed by pathology were analyzed retrospectively. The image characteristics included the lesion location and size, contribution of cystic and solid components, intratumoral necrosis or hemorrhage, invasion of perinephric tissue and renal sinus, lymphadenopathy, major venous or arterial vascular invasion, pattern of the tumor growth, intratumor calcification and lipids, homogeneity of SI on T2-weighted images, attenuation and SI of the mass with respect to the normal renal cortex on precontrast and contrasted CT/MRI images, tumor SIs, tumor attenuations and tumor-to-cortex indices, homogeneity of enhancement on the contrasted images.

RESULTS

The mean age was 32 years (range, 15-47 years). Most patients (4/5) were women. All tumors showed a cortical location. The average tumor size was 9 cm (range, 4-18 cm). Four tumors comprised a predominantly solid lesion with focal necrosis, and one tumor comprised a solid lesion with significant necrosis. All tumors showed intertumor hemorrhage, infiltrative growth and invasion of the perirenal adipose/renal sinus. Four cases showed retroperitoneal lymphadenopathy, of which one case showed simultaneous mediastinal and supraclavicular lymphadenopathy. All tumors from four cases showed mild hyperintensity on T1-weighted MRI images, and three tumors showed hypointensity on T2-weighted MRI images relative to the renal cortex except for 1 tumor that showed significant hemorrhage and a relative hyperintensity. For 3 cases who were imaged with CT, two tumors imaged using nonenhanced CT images showed mild hyperdensity relative to the renal cortex. Calcification was noted in all three tumors. All tumors showed mild, persistent enhancement.

CONCLUSION

Typical Xp11-RCC manifests as an advanced, solid renal mass with mild persistent enhancement, a prevalence of intertumor hemorrhage/calcification, and a cortical epicenter location. The predilection for children and young adults is a useful clinical feature when confirming a diagnosis of Xp11-RCC.

Targeted therapies and the treatment of non-clear cell renal cell carcinoma

BACKGROUND

Targeted therapies have shown profound effects on the outcome of patients with advanced renal cell carcinoma (RCC). However, the optimal treatment for RCC of non-clear cell histology (nccRCC)-typically excluded from trials of targeted agents-remains uncertain.

MATERIALS AND METHODS

By carrying out extensive searches of PubMed and ASCO databases, we identified and summarised research into the biological characteristics, clinical behaviour and treatment of different histological subtypes of nccRCC, focusing on targeted therapy.

RESULTS

The available data suggest that treatments currently approved for RCC are active in ncc subtypes, although the overall clinical benefit may be less than for clear cell RCC. Temsirolimus has proven benefit over interferon-alfa (IFN-α) in patients with nccRCC, based on phase III data, while everolimus, sunitinib and sorafenib have all demonstrated some degree of activity in nccRCC in expanded-access trials. No clear picture has emerged of whether individual histological subtypes are particularly responsive to any individual treatment.

CONCLUSIONS

Further molecular studies into the pathogenesis of RCC histological subtypes will help direct the development of novel, appropriate targeted agents. Clinical trials specifically designed to evaluate the role of targeted agents in nccRCC are ongoing, and data from trials with sunitinib and everolimus will be reported soon.

Management of renal collecting duct carcinoma: a systematic review and the McMaster experience

INTRODUCTION

Collecting duct carcinoma (cdc) is a rare, aggressive form of renal carcinoma that presents at an advanced stage and has a poor prognosis. Little is known concerning the optimal management of cdc. We present the results of a systematic review addressing the management of cdc and the McMaster University cdc series.

METHODS

The medline, Cochrane Library, and embase databases and conference proceedings were searched to identify studies relating to the management of cdc. Included studies reported on a minimum of 10 subjects receiving a single intervention. Series in which an evaluation of therapeutic effectiveness was not possible were excluded. The McMaster University (Hamilton, Ontario) series of 6 cases of cdc were retrospectively reviewed.

RESULTS

We identified 3 studies relevant to the management of cdc that included a total of 72 patients. A gemcitabine-cisplatin or -carboplatin regimen resulted in a 26% objective response rate in 23 patients with metastatic cdc. Two additional studies indicated that 49 patients treated with immunotherapy achieved no response. In the McMaster series, cytoreductive nephrectomy was performed in 4 of 6 patients. In 2 patients, mvac therapy (methotrexate-vinblastine-doxorubicin-cisplatin) achieved no response. No significant therapeutic complications occurred, but survival was poor (median: 11 months; range: 10-33 months).

CONCLUSIONS

Our review and clinical experience suggest that the current standard of care for metastatic cdc is a gemcitabine-cisplatin regimen.

The MSCT and MRI findings of collecting duct carcinoma

AIM

To characterize the multi-section computed tomography (MSCT) and magnetic resonance imaging (MRI) features of collecting duct carcinoma (CDC).

MATERIALS AND METHODS

Twenty patients with CDC were studied retrospectively using MSCT (n = 20), and MSCT and MRI (n = 5). MSCT and MRI were undertaken to investigate tumour location, size, radiodensity, cystic or solid appearance, calcification, capsule, signal, enhancement pattern, and metastases.

RESULTS

Tumours (mean diameter 3.6 ± 1.7 cm) were solitary (20/20), solid (18/20), had cystic components (12/20), calcifications (12/20), poorly defined (18/20), were centred in the medulla (20/20), compressed the renal pelvis (12/20), and had lymph node metastases (2/20). On unenhanced computed tomography (CT), the radiodensity of the CDC was greater than that of the normal renal cortex or medulla (43.8 ± 2.4 versus 37.6 ± 5.1 or 32.6 ± 4.1, p = 0.041, n = 20). Five patients with CDC underwent MRI, which revealed cystic components (4/5), poorly defined CDC (5/5), and none of the patients had lymph node metastasis. The CDC was isointense on T1-weighted imaging, and iso- or hypointense on T2-weighted imaging. Enhancement was lower within the CDC than the renal cortex and medulla during all enhanced phases (p = 0.032, 0.001, 0.018, respectively, n = 20).

CONCLUSION

CDC should be considered when a renal tumour is centred in the medulla, with increased radiodensity on unenhanced CT and reduced enhancement compared to the adjacent cortex or medulla.

The multislice CT findings of renal carcinoma associated with XP11.2 translocation/TFE gene fusion and collecting duct carcinoma

BACKGROUND

Renal cell carcinoma associated with Xp11.2 translocation and TFE gene fusion (Xp11.2/TFE RCC), and collecting duct carcinoma (CDC) are uncommon subtypes of renal cell carcinomas.

PURPOSE

To investigate the multislice CT (MSCT) characteristics of these two tumor types.

MATERIAL AND METHODS

Nine patients with Xp11.2/TFE RCC and 10 patients with CDC were studied retrospectively. MSCT was undertaken to investigate differences in tumor characteristics and enhancement patterns.

RESULTS

All patients had single tumors centered in the renal medulla. Two patients with each tumor type had lymph node involvement and there was a single case of hepatic metastasis (Xp11.2/TFE RCC). The mean tumor diameter of Xp11.2/TFE RCC tumors was significantly larger than for CDC tumors. Two patients with Xp11.2/TFE RCC had cystic components as did eight patients with CDC (P < 0.05). Calcifications were present in six patients, each with CDC. Clear tumor boundaries were visible in two patients with CDC and in nine with Xp11.2/TFE RCC (P < 0.05). The density of Xp11.2/TFE RCC tumors was greater than that of CDC tumors, normal renal cortex, or medulla on unenhanced CT. Enhancement was higher with Xp11.2/TFE RCC than with CDC tumors during all phases. Xp11.2/TFE RCC enhancement was higher than in the renal medulla during cortical and medullary phase but lower than in normal renal medulla during the delayed phase. CDC tumor enhancement was lower than that for normal renal medulla during all enhanced phases.

CONCLUSION

Both tumor types originated from the renal medulla. Distinguishing features included density on unenhanced CT, enhancement patterns, and capsule signs. Identifying these differences may aid diagnosis.

Rare (<1%) histological subtypes of renal cell carcinoma: an update

Recent advances in genetics and pathology have allowed description of several new histological subtypes of renal cell carcinoma (RCC) as well as better characterization of other rare subtypes. We herein present a comprehensive review of taxonomy, epidemiology, pathology, imaging findings, and natural history of a wide spectrum of rare subtypes of RCCs that individually constitute <1% of all the RCCs.

A case report of collecting duct carcinoma of the kidney coexistent with giant adrenal myelolipoma

Collecting duct carcinoma (CDC) of the kidney coexistent with giant adrenal myelolipoma is rare. We report a case of 70-year-old female who presented with a history of gross hematuria and back pain. On investigation, she had a mass in the left kidney and left adrenal gland, respectively. The patient underwent left radical nephrectomy with left adrenalectomy. Pathological findings revealed a renal CDC with partial aquamous metaplasia, in addition to an adrenal myelolipoma. Interleukin-2 was administered for 3 months after operation. Neither signs of recurrence nor metastasis has developed after a 4-year follow-up.

Common and uncommon adult unilateral renal masses other than renal cell carcinoma

Many different masses can involve the kidney other than the commonly encountered renal cell carcinoma (RCC). The purpose of this article is to review the characteristic clinical and imaging findings of common and uncommon masses that predominantly present unilaterally in the adult patient, other than RCC. Awareness of such lesions and knowing the clinical scenario is important for appropriate diagnosis and management, especially in a multidisciplinary care setting.

Cystic embryonal sarcoma of the kidney: report of a case with US and CT findings

Here we report a case in a 41-year-old woman histologically proven cystic embryonal sarcoma of the kidney, with emphasis on the imaging findings and pathological features. A large lobulated solid mass in the cystically dilated pelvocalyceal region was accompanied with hydroureter as depicted on both ultrasound and contrast-enhanced CT images.

Computed tomography and magnetic resonance imaging features of lesions of the renal medulla and sinus

The kidneys can harbor a wide variety of lesions, many of which can be visualized by computed tomography and magnetic resonance imaging. In this article, the pertinent renal anatomic relationships as well as the histologic composition and function of the renal medulla and sinus are reviewed. Additionally, computed tomography and magnetic resonance imaging features of renal sinus and medullary lesions in adult patients are presented. This article reviews the salient imaging features of various malignant, benign neoplastic, and nonneoplastic lesions of the sinus and medulla.

Extrarenal multiorgan metastases of collecting duct carcinoma of the kidney: a case series

Introduction

Collecting duct carcinoma is a rare type of renal cell carcinoma. The primary is difficult to diagnose on imaging, and metastases are often present on initial presentation. Extensive multiorgan metastases can result in complex presentations that can be difficult to diagnose.

Case presentation

We present two case reports of multiorgan metastases of collecting duct carcinoma that were autopsy confirmed. The first case was a 55-year-old man who presented with fever and abdominal pain. Abdominal computed tomography showed enlargement of the right kidney. Pyelonephritis was considered on the basis of laboratory test results and imaging findings. However, multiple cavitary lesions were found on routine chest radiography. These lesions were biopsied, resulting in a histological diagnosis of metastatic adenocarcinoma. A renal tumor was considered. Transitional cell carcinoma was suspected, which proved to be misdiagnosed and chemotherapy was given accordingly. However, this was not effective and the patient died after 2 months. Autopsy demonstrated the primary tumor to be collecting duct carcinoma, with metastases to lung, liver, spleen, bone marrow, right adrenal gland, and para-aortic lymph node. Computed tomography done while the patient was alive detected lung, liver, and para-aortic lymph node metastases. The second case was a 77-year-old man who presented with fever. Pyelonephritis was considered on the basis of the laboratory test results and imaging findings. Antibiotic therapy improved his symptoms and laboratory indicators of inflammation. One year later, he developed backache. Computed tomography revealed a progressively enlarging right renal lesion, multiple liver masses, enlargement of the para-aortic lymph nodes, and multiple osteoblastic and osteoclastic lesions. A renal tumor with multiple metastases was diagnosed. Chemotherapy was given without effect, and the patient died of cardiac failure 1 year later. Autopsy revealed a primary tumor of collecting duct carcinoma with metastases to the liver, right adrenal gland, right upper ureter, bone marrow, para-aortic and mediastinal lymph nodes, and bone.

Conclusion

We present the radiological findings of lung, liver, lymph node, and bone metastases in two patients with collecting duct carcinoma.

MRI of the kidney-state of the art

Ultrasound and computed tomography (CT) are modalities of first choice in renal imaging. Until now, magnetic resonance imaging (MRI) has mainly been used as a problem-solving technique. MRI has the advantage of superior soft-tissue contrast, which provides a powerful tool in the detection and characterization of renal lesions. The MRI features of common and less common renal lesions are discussed as well as the evaluation of the spread of malignant lesions and preoperative assessment. MR urography technique and applications are discussed as well as the role of MRI in the evaluation of potential kidney donors. Furthermore the advances in functional MRI of the kidney are highlighted.

Segmental disorders of the nephron: histopathological and imaging perspective

Recent advances in molecular genetics and immunocytochemistry have clarified the cell of origin in many renal disorders. Several renal disorders are thought to involve specific segments of the nephron. Renin-secreting tumours arise from juxtaglomerular cells. Clear cell and papillary renal cell carcinoma (RCC) recapitulate the epithelium of the proximal tubules. Oncocytoma and chromophobe RCC differentiate towards Type A and Type B intercalated cells of the cortical collecting duct, respectively. Medullary collecting ducts are the target sites for the development of autosomal recessive polycystic kidney disease, collecting duct carcinoma and medullary carcinoma. Renal papillae are susceptible to unique changes such as necrosis or papillitis. The purpose of our article is threefold: to illustrate the imaging findings of renal disorders that show segmental involvement of the nephron, to describe proximal and distal nephron disorders and to correlate imaging findings of some entities with histopathological features.

Common and uncommon histologic subtypes of renal cell carcinoma: imaging spectrum with pathologic correlation

Renal cell carcinoma (RCC) is a cause of significant morbidity and mortality, with an estimated 35,000 new cases and 12,480 deaths in the United States in 2003. Recent advances in imaging technology, pathology, urology, and oncology permit early diagnosis of RCC and facilitate optimal management. The 2004 World Health Organization classification for renal neoplasms recognizes several distinct histologic subtypes of RCC. These subtypes include clear cell RCC, papillary RCC, chromophobe RCC, hereditary cancer syndromes, multilocular cystic RCC, collecting duct carcinoma, medullary carcinoma, mucinous tubular and spindle cell carcinoma, neuroblastoma-associated RCC, Xp11.2 translocation-TFE3 carcinoma, and unclassified lesions. Different histologic subtypes of RCC have characteristic histomorphologic and biologic profiles. Clear cell RCC is the most common subtype and has a less favorable prognosis (stage for stage) than do papillary RCC and chromophobe RCC. Collecting duct carcinoma and renal medullary carcinoma are associated with aggressive clinical behavior and a poor prognosis.

Unusual renal cell carcinomas: a pictorial essay

Renal cell carcinoma (RCC) is the most common solid renal neoplasm. Clear cell (conventional) carcinoma is the most common pathologic subtype of RCC. Usually RCC is a hypervascular, solid, solitary mass with contour bulging. However, RCC can manifest different features according to the pathologic tumor subtypes. Preoperative diagnosis of cyst-associated RCC is very difficult, especially in cases of RCC originating in a cyst. Multiple or bilateral presentation of RCC occurs in fewer than 5% of cases. In addition, RCCs may demonstrate unusual findings such as infiltrative growth mimicking transitional cell carcinoma, fatty component mimicking angiomyolipoma, severe perinephric infiltration, and extensive calcifications mimicking inflammation or other tumor. RCCs can be associated with hereditary diseases such as von Hippel-Lindau disease. Familiarity with these radiologic features of unusual RCCs can help ensure correct diagnosis and proper management.

Collecting duct carcinoma of the kidney: CT and pathologic correlation

PURPOSE

We characterized CT findings of collecting duct carcinoma of the kidney and correlated these with the histopathologic findings.

MATERIALS AND METHODS

CT scans of 18 patients with pathologically proven collecting duct carcinoma of the kidney were retrospectively reviewed. We analyzed CT findings of collecting duct carcinoma and also correlated CT findings with the histopathologic findings.

RESULTS

The mean size of the tumors was 6.9 cm and all cases were solid. Seventeen (94%) tumors had a medullary location. Nine (69%) and 11 (85%) cases showed weak and heterogeneous enhancement, respectively. A cystic component (50%) was frequently seen within the tumors. Lymphadenopathy and metastasis were noted in 10 (56%) and 6 (33%) cases, respectively. Perinephric stranding and vascular invasion were present in 10 (56%) and 5 (28%) cases, respectively. In 17 (94%) of the 18 cases, involvement of the renal sinus was present. Infiltrative growth (67%) and preservation of the renal contour (61%) were more common than expansile growth (33%) and exophytic configuration (39%), respectively. These CT features were well correlated with the histopathologic findings.

CONCLUSION

Medullary location, weak and heterogeneous enhancement, involvement of the renal sinus, infiltrative growth, preserved renal contour, and a cystic component are CT findings frequently seen in patients with collecting duct carcinoma of the kidney. CT findings are nevertheless nonspecific and do not allow collecting duct carcinoma to be easily differentiated from the other subtypes of renal cell carcinoma. However, when CT demonstrates a renal tumor with these findings, collecting duct carcinoma can be considered in the differential diagnosis.

Magnetic Resonance Imaging of the Kidney

High tissue contrast, multiplanar image capabilities, and tissue characterization render MR into an ideal imaging modality for effective evaluation of a wide range of renal disorders. It provides high details of anatomy and can suggest the composition of lesions. Improvements of MRI technology during the last years have made MRI increasingly attractive for body imaging. Fast imaging sequences and parallel imaging techniques have proved to be useful in minimizing artifacts from respiratory motion and magnetic susceptibility differences providing superior imaging quality. Additionally, the use of renally eliminated paramagnetic contrast agents permits assessment of parenchymal perfusion and visualization of the excretion of the contrast medium providing information on renal function.

Neoplasms of the Renal Medulla: Radiologic-Pathologic Correlation

Tumors of the renal medulla cover a wide spectrum, with characteristic histomorphology and variable biologic profiles. Renal medullary tumors can be categorized into benign and malignant neoplasms based on histologic features and clinico-biologic behavior. They can be further classified into pediatric and adult tumors based on the patient age group. When small, renal medullary tumors may be differentiated from the more common renal adenocarcinomas by their central location and certain demographic characteristics. Although most large malignant medullary tumors demonstrate imaging findings that are indistinguishable from those of other renal malignancies, some tumors demonstrate imaging findings that may suggest a specific diagnosis.

Bilateral collecting duct carcinoma presenting with tumour associated nephritis and end-stage renal failure. A case report and review of the literature

We present a 55 year old male who was investigated for painless macroscopic haematuria and had essentially normal radiological and cystoscopic findings. He progressed rapidly and was eventually diagnosed with a Collecting Duct Carcinoma. This case is of interest as it is the first reported case of Collecting Duct Carcinoma occurring bilaterally. It is also the first case to cause end stage renal failure requiring dialysis due to extensive tubular involvement. Finally, it is the first time this malignancy has been found to cause a tumour associated nephritis. We describe the clinical course and present the various histological findings followed by a review of the literature.

Hereditary renal cancers

Hereditary renal cancer syndromes can lead to multiple bilateral kidney tumors that occur at a younger age than do nonhereditary renal cancers. Imaging plays an important role in the diagnosis and management of these syndromes. During the past decade, several new hereditary renal syndromes have been discovered but are not yet widely known. Whereas previously, the list of hereditary renal cancers in adults included von Hippel-Lindau disease and a rare form of chromosomal translocation, the list now includes the following syndromes: tuberous sclerosis, hereditary papillary renal cancer, Birt-Hogg-Dubé syndrome, hereditary leiomyoma renal cell carcinoma, familial renal oncocytoma, hereditary nonpolyposis colon cancer, and medullary carcinoma of the kidney. In addition, a number of newly described but poorly understood syndromes are under investigation. Even at this early stage, it is clear that elucidation of the underlying genetic mutations that cause hereditary renal cancer syndromes will have profound implications for understanding the origins of nonhereditary renal tumors. These studies will likely culminate in a better understanding of the causes of renal cancer, its prevention, and, ultimately, its cure.

Treatment outcome and survival associated with metastatic renal cell carcinoma of non-clear-cell histology

PURPOSE

To define outcome data for patients with metastatic renal cell carcinoma (RCC) with histology other than clear-cell type, including collecting duct (or medullary carcinoma), papillary, chromophobe, and unclassified histologies.

PATIENTS AND METHODS

Sixty-four patients with metastatic non-clear-cell RCC histology were the subjects of this retrospective review. Included in the analysis were 22 (8%) of 286 patients from a clinical trials database, 19 of 1,166 patients from a surgery database, and 23 of 357 patients from a pathology database.

RESULTS

The prevalent histology was collecting duct, present in 26 (41%) patients. The number of patients with chromophobe and papillary histologies was 12 (19%) and 18 (28%), respectively. Eight (12%) of the patients had tumors that could not be classified for specific tumor histology. Among the 43 patients treated with 86 systemic therapies, including 37 cytokine therapies, two patients (5%) were observed to have a partial response. The median overall survival time was 9.4 months (95% confidence interval, 8 to 14 months). The survival was longer for patients with chromophobe tumors compared with collecting duct or papillary histology, and this group included four patients with survival of greater than 3 years.

CONCLUSION

RCC consists of a heterogeneous group of tumors including clear-cell, papillary, chromophobe, collecting duct, and unclassified cell types. Non-clear-cell histologies constitute less than 10% of patients in general populations of patients with advanced RCC treated on clinical trials. Metastatic non-clear-cell RCC is characterized by a resistance to systemic therapy and poor survival, with the survival for patients with chromophobe tumors longer than that for patients with metastatic collecting duct or papillary RCC. Treatment with novel agents on clinical trials is warranted.