Hereditary renal cancers

Unilateral renal oncocytosis and combined hybrid tumor: a case report and review of the literature

Renal oncocytosis is a very rare cause of multiple renal masses. Imaging features of renal oncocytosis and combined tumors have rarely been reported. Here, we describe a case of unilateral left renal oncocytosis and a combined hybrid tumor between chromophobe renal cell carcinoma and oncocytoma, which were depicted on CT and MR imaging as multiple enhancing solid masses with one dominant mass. Additionally, we reviewed the literature.

Uroepithelial and kidney carcinoma in Lynch syndrome

Increased risk for urological tumors has been observed in mutation carriers with Lynch syndrome (LS). In this study, we evaluated the clinical features of uroepithelial (bladder and ureter) and kidney cancers in 974 Finnish mutation carriers. Altogether 30 patients had a total of 34 urological tumors: 12 ureter, 12 bladder, and 10 kidney cancers. Urological tumor was the only tumor in 9 (30 %) patients, and metachronous other tumor occurred in 21 (70 %). The occurrence of uroepithelial cancers was significantly higher in MSH2 mutation carriers (6 %; 95 % CI, 2.7-11.0) than in MLH1 carriers (2 %; 95 % CI, 1.1-3.2) and MSH6 mutation carriers (0 %) (p = 0.014). The mean ages of patients at the time of diagnosis were: bladder cancer, 57 years; ureter cancer, 58 years; and kidney cancer, 64 years. Overall 5-year survival rates were 70 % (95 % CI, 0.32-0.89) in bladder cancer, 81 % (95 % CI, 0.45-0.95) in ureter cancer, and 75 % (95 % CI, 0.31-0.93) in kidney cancer. Cancer-specific 5-year survival rates were 70 % (95 % CI, 0.32-0.89) in bladder cancer, 91 % (95 % CI, 0.51-0.98) in ureter cancer, and 100 % in kidney cancer. In conclusion, early age of onset was observed in patients with uroepithelial tumors, but not in patients with kidney cancer. The frequency of uroepithelial tumors was significantly higher in MSH2 mutation carriers than in MLH1 carriers. Further studies with larger numbers of patients, however, are needed to evaluate the potential benefit of surveillance of urological tumors in LS.

Hereditary renal tumor syndromes: imaging findings and management strategies

OBJECTIVE

It is not rare for the radiologist to identify multiple renal masses and be the first to raise the possibility of a hereditary renal tumor syndrome. Characteristic renal and extrarenal imaging findings aid in making the correct diagnosis. The imaging findings, screening guidelines, and management techniques for the most common hereditary renal tumor syndromes are reviewed.

CONCLUSION

Hereditary renal tumor syndromes have specific screening guidelines and unique management techniques in which imaging plays a central role.

Malignant pigmented clear cell epithelioid cell tumor (PEComa) in an adolescent boy with widespread metastases: a rare entity in this age group

Malignant pigmented clear cell epithelioid cell tumor of the kidney is a rare variant of perivascular epithelioid cells tumors (PEComa) or epithelioid angiomyolipoma (AML). PEComa is characteristically composed purely of epitheloid cells. The fat cells and the blood vessels that are typical of classic AML are absent. Most epithelioid AML cases are benign; however, malignant epithelioid AML of the kidney has been occasionally reported in adults in association with tuberous sclerosis. We report the radiological-pathological features of a malignant pigmented clear cell epithelioid renal tumor in a 15-year-old boy presenting with extensive metastases but without clinical evidence of tuberous sclerosis.

Mouse models of inherited cancer syndromes

Animal models of cancer have been instrumental in understanding the progression and therapy of hereditary cancer syndromes. The ability to alter the genome of an individual mouse cell in both constitutive and inducible approaches has led to many novel insights into their human counterparts. In this review, knockout mouse models of inherited human cancer syndromes are presented and insights from the study of these models are highlighted.

Renal cell cancer among African Americans: an epidemiologic review

Incidence rates for renal cell cancer, which accounts for 85% of kidney cancers, have been rising more rapidly among blacks than whites, almost entirely accounted for by an excess of localized disease. This excess dates back to the 1970s, despite less access among blacks to imaging procedures in the past. In contrast, mortality rates for this cancer have been virtually identical among blacks and whites since the early 1990s, despite the fact that nephrectomy rates, regardless of stage, are lower among blacks than among whites. These observations suggest that renal cell cancer may be a less aggressive tumor in blacks. We have reviewed the epidemiology of renal cell cancer, with emphasis on factors which may potentially play a role in the observed differences in incidence and mortality patterns of renal cell cancer among blacks and whites. To date, the factors most consistently, albeit modestly, associated with increased renal cell cancer risk in epidemiologic studies among whites--obesity, hypertension, cigarette smoking--likely account for less than half of these cancers, and there is virtually no epidemiologic evidence in the literature pertaining to their association with renal cell cancer among blacks. There is a long overdue need for detailed etiologic cohort and case-control studies of renal cell cancer among blacks, as they now represent the population at highest risk in the United States. In particular, investigation of the influence on renal cell cancer development of hypertension and chronic kidney disease, both of which occur substantially more frequently among blacks, is warranted, as well as investigations into the biology and natural history of this cancer among blacks.

Role of FDG PET/CT in imaging of renal lesions

Focal incidental renal lesions are commonly encountered on positron emission tomography (PET)/computed tomography (CT) imaging. The vast majority of these lesions are benign. However, the interpretation of renal lesions can be problematic if the imaging criteria of simple cysts are not met. Limited literature exists on the characterisation of renal masses with metabolic imaging. The purpose of this article is to focus on the imaging features of benign and malignant renal masses with PET/CT. The lesions discussed include renal cyst, angiomyolipoma, oncocytoma, renal cell carcinoma, renal metastases and other infiltrating neoplastic processes affecting the kidney. Both the anatomical and metabolic features which characterise these benign and malignant entities are described. We emphasise the importance of viewing the CT component to identify the typical morphological features and discuss how to best use hybrid imaging for management of renal lesions. Metabolic imaging has a promising role in the imaging of renal lesions and can help prevent unnecessary biopsies and ensure optimal management of suspicious lesions.

Characterization of complex renal cysts: a critical evaluation of the Bosniak classification

OBJECTIVE

Complex renal cysts represent a major clinical problem, since it is often difficult to exclude malignancy. The Bosniak classification system, based on computed tomography (CT), is widely used to categorize cystic renal lesions. The aim of this study was to evaluate critically available data on the Bosniak classification.

MATERIAL AND METHODS

All publications from an Entrez Pubmed search were reviewed, focusing on clinical applicability and the use of imaging modalities other than CT to categorize complex renal cysts.

RESULTS

Fifteen retrospective studies were found. Most series were small, with only six studies comprising more than 30 patients. When the results of these six studies were pooled the percentage of malignancy was: category I, 0%; category II, 15.6%; category IIF, 0%; category III, 65.3%; and category IV, 91.7%. Category IIF was included in only three studies. Both magnetic resonance imaging and contrast-enhanced ultrasonography (US) seemed to have reasonable agreement with CT, although both modalities had a tendency to upgrade lesions.

CONCLUSIONS

The main problem with the Bosniak classification is in separating category II and III lesions, which is of major importance, since decisions on intervention are based on this separation. The use of category IIF seems promising to detect those category II lesions that eventually will develop into malignancy and reduce overtreatment of lesions originally classified as category III. The scientific basis of this "new" classification strategy is, however, still missing. Data on other imaging modalities are too limited for conclusions to be drawn.

[Birt-Hogg-Dubé syndrome : bilateral oncocytic kidney tumors in a patient]

We report on a rare case of bilateral oncocytic kidney tumors in a patient with Birt-Hogg-Dubé syndrome (BHD). BHD is an autosomal inherited cancer syndrome associated with multiple kidney tumors, benign cutaneous tumors, and pulmonary cysts with spontaneous pneumothorax. To date about 50 BHD families have been described. Patients are best treated with nephron-sparing surgery. Close follow-up is mandatory because recurrence in previously operated kidneys and metastatic tumor progression can occur. Family members at risk should also early be screened for BHD.

A pictorial review of imaging of abdominal tumours in adolescence

Neoplastic abdominal tumours, particularly those originating from embryonal tissue (such as hepatoblastoma and nephroblastoma) and neural crest cells (such as neuroblastoma), are well-documented in young children. Neoplasms of adulthood, most commonly carcinoma of different visceral organs, are also well-documented. Abdominal tumours in adolescence constitute a distinct pathological group. The radiological features of some of these tumours have been described only in isolated reports. The purpose of this pictorial essay was to review the imaging findings of various kinds of abdominal tumours in adolescent patients (with an age range of 10-16 years) who presented to the Children Cancer Center of our institution in the past 15 years. Some tumours, though rare, have characteristic imaging appearances (especially in CT) that enable an accurate diagnosis before definite histological confirmation.

Hereditary renal cancer syndromes: an update of a systematic review

CONTEXT

Hereditary renal cancers (HRCs) comprise approximately 3-5% of renal cell carcinomas (RCCs).

OBJECTIVE

Our aim was to provide an overview of the currently known HRC syndromes in adults.

EVIDENCE ACQUISITION

Data on HRC syndromes were analysed using PubMed and Online Mendelian Inheritance in Man with an emphasis on kidney cancer, clinical criteria, management, treatment, and genetic counselling and screening.

EVIDENCE SYNTHESIS

Ten HRC syndromes have been described that are inherited with an autosomal dominant trait. Eight genes have already been identified (VHL, MET, FH, FLCN, TSC1, TSC2, CDC73, and SDHB). These HRC syndromes involve one or more RCC histologic subtypes and are generally bilateral and multiple. Computed tomography and magnetic resonance imaging are the best imaging techniques for surveillance and assessment of renal lesions, but there are no established guidelines for follow-up after imaging. Except for hereditary leiomyomatosis RCC tumours, conservative treatments favour both an oncologically effective therapeutic procedure and a better preservation of renal function.

CONCLUSIONS

HRC involves multiple clinical manifestations, histologic subtypes, genetic alterations, and molecular pathways. Urologists should know about HRC syndromes in the interest of their patients and families.

Patient responses to genetic information: studies of patients with hereditary cancer syndromes identify issues for use of genetic testing in nephrology practice

Advances in the genetic basis of kidney disease may mean that genetic testing is increasingly important in reducing disease morbidity and mortality among patients. However, there is little research examining patient responses to genetic information for Mendelian and common kidney diseases. Existing research on kidney and other hereditary cancer syndromes can inform three major issues relevant to the nephrology context as follows: (1) how patients understand their risk of disease after genetic counseling and testing, (2) their emotional responses to the information, and (3) their uptake of recommended risk-reducing strategies. Prior research suggests that genetic counseling and testing may improve patient understanding of genetics, but patients still might not fully understand the meaning of their results for disease risk. Genetic counseling and testing does not appear to result in long-term negative emotional effects among patients who carry mutations or those who do not. Finally, although genetic counseling and testing may improve adherence to recommended screening strategies, adherence varies substantially across different risk-reduction options. Previous research also suggests that computer-based interventions might be a useful adjunct to genetic counseling approaches. Examining whether and how these prior findings relate to the context of hereditary kidney disease is an important area for future research.

Hereditary causes of kidney tumours

BACKGROUND

In most cases of renal cell carcinoma there is no family history of renal cancer and no hereditary cause of the disease. Hereditary renal cancer accounts for about 2-4% of cases. Recognition of this subgroup by clinicians is important because of the possibility of severe medical consequences for patients and their relatives.

MATERIALS AND METHODS

We review the latest data about different genetic conditions characterized by an increased risk of developing renal cancer and we formulate tools to recognize high-risk families.

RESULTS

In general, a positive family history, young age at diagnosis of renal cancer, multiple and/or bilateral renal tumours and combined occurrence of different histological types of renal tumours should raise suspicion of a hereditary renal tumour syndrome. In addition, the presence of specific extrarenal symptoms in patients could assist in differentiating between tumour syndromes.

CONCLUSIONS

A detailed medical and family history, along with physical examination are key factors to diagnose hereditary renal cancer syndromes. When a genetic predisposition for renal cancer is suspected, referral to a Family Cancer Clinic is warranted to initiate genetic examination and counselling on preventive options.

Age dependence of radiation-induced renal cell carcinomas in an Eker rat model

Exposure to carcinogens early in life may contribute to cancer development later in life. The amount of radiation exposure children experience during medical procedures has been increasing, so it is important to evaluate the radiation risk of cancer in developing organs. Toward this goal, we assessed the risk of developing renal cell carcinoma using Eker rats as a kidney tumor model. F1 hybrids of male Eker (Tsc2 mutant) and female F344 rats were irradiated with 0.5 or 2 Gy gamma radiation on gestation days 15 and 19, and on postnatal days 5, 20, and 49. At 27 weeks of age, kidneys were examined for proliferative lesions. Preneoplastic lesions such as phenotypically altered tubules increased after postnatal irradiation as a function of age-at-irradiation, and hyperplasia were greatly increased after perinatal and postnatal irradiation. In contrast, development of adenoma and adenocarcinoma were evident in animals irradiated at perinatal ages, being maximal at gestational day 19. The frequency of LOH at the Tsc2 locus was unexpectedly low - 0% (0 of 4) for the unirradiated control, and 17% (6 of 35) for the irradiated group. Irrespective of LOH, the mTOR (mammalian target of rapamycin) pathway, which is negatively regulated by the Tsc1/2 complex, was activated in both benign and malignant lesions, as evidenced by phosphorylation of S6 ribosomal protein and 4E-BP1. This suggests that the wild-type Tsc2 allele may be functionally inactivated. In conclusion, actively growing kidneys in perinatal-aged (F344 x Eker) F1 rats (Tsc2(+/-)) are at risk for radiation-induced malignant transformation of the renal epithelium associated with mTOR activation.

Population-based survey of cancer risks in chromosome 3 translocation carriers

Familial renal cell carcinoma (RCC) is genetically heterogeneous and may be associated with germline mutations in a number of genes. Twelve different constitutional translocations involving chromosome 3 have also been described in association with inherited RCC. In some families the lifetime risk of RCC in chromosome 3 translocation carriers has been estimated to be more than 80%; however the cancer risks in patients with chromosome 3 translocations not ascertained because of a family history of RCC are not well defined. We report a retrospective population-based study using Danish national cytogenetic and cancer registries to clarify tumor risks associated with constitutional translocations involving chromosome 3. We identified 222 (105 females, 117 males) individuals with a constitutional chromosome 3 translocation and compared their cancer risks to those of the Danish population. None of the chromosome 3 translocation carriers had developed RCC at the time of study (female 95% CIs 0.000-0.042, male 95% CIs 0.000-0.038) (P = 1.0 and P = 0.498 for females and males compared to Danish population). Fourteen translocation carriers had developed cancer but there was no evidence of an excess of early onset disease and lifetime cancer risks in chromosome 3 translocation carriers were similar that in the Danish population. There was no association between cancer risk and location of the chromosome 3 breakpoint (HR = 1.322, P = 0.673). These findings suggest that, in the absence of a family history of RCC or evidence of disruption of a specific tumor suppressor gene, chromosome 3 translocations carriers are not at high risk of developing RCC.

Birt-Hogg-Dubé syndrome: diagnosis and management

Birt-Hogg-Dubé syndrome (BHD) is an autosomal dominant condition characterised clinically by skin fibrofolliculomas, pulmonary cysts, spontaneous pneumothorax, and renal cancer. The condition is caused by germline mutations in the FLCN gene, which encodes folliculin; the function of this protein is largely unknown, although FLCN has been linked to the mTOR pathway. The availability of DNA-based diagnosis has allowed insight into the great variation in expression of FLCN, both within and between families. Patients can present with skin signs and also with pneumothorax or renal cancer. Preventive measures are aimed mainly at early diagnosis and treatment of renal cancer. This Review gives an overview of current diagnosis and management of BHD.

Tuberous sclerosis with pulmonary lymphangioleiomyomatosis and renal angiomyolipomas. Computed tomographic findings: a case report

The authors describe a case of a 31-year-old female with tuberous sclerosis, a genetic, rare, variably expressed disease. Clinical symptoms were chest pain, and progressive dyspnea. Computed tomography scan of the chest showed bilateral, diffuse, small thin-walled cysts scattered throughout the lungs characteristic for pulmonary lymphangioleiomyomatosis. Computed tomography scan of the abdomen revealed enlarged, heterogeneous kidneys, with low density tumors corresponding to angiomyolipomas. Pulmonary lymphangioleiomyomatosis and bilateral renal angiomyolipomas are some presentations of tuberous sclerosis and the coexistence of both conditions may cause devastating morbidity and mortality.

Tuberous sclerosis with pulmonary lymphangioleiomyomatosis and renal angiomyolipomas. Computed tomographic findings: a case report

The authors describe a case of a 31-year-old female with tuberous sclerosis, a genetic, rare, variably expressed disease. Clinical symptoms were chest pain, and progressive dyspnea. Computed tomography scan of the chest showed bilateral, diffuse, small thin-walled cysts scattered throughout the lungs characteristic for pulmonary lymphangioleiomyomatosis. Computed tomography scan of the abdomen revealed enlarged, heterogeneous kidneys, with low density tumors corresponding to angiomyolipomas. Pulmonary lymphangioleiomyomatosis and bilateral renal angiomyolipomas are some presentations of tuberous sclerosis and the coexistence of both conditions may cause devastating morbidity and mortality.

Tuberous sclerosis with pulmonary lymphangioleiomyomatosis and renal angiomyolipomas. Computed tomographic findings: a case report

The authors describe a case of a 31-year-old female with tuberous sclerosis, a genetic, rare, variably expressed disease. Clinical symptoms were chest pain, and progressive dyspnea. Computed tomography scan of the chest showed bilateral, diffuse, small thin-walled cysts scattered throughout the lungs characteristic for pulmonary lymphangioleiomyomatosis. Computed tomography scan of the abdomen revealed enlarged, heterogeneous kidneys, with low density tumors corresponding to angiomyolipomas. Pulmonary lymphangioleiomyomatosis and bilateral renal angiomyolipomas are some presentations of tuberous sclerosis and the coexistence of both conditions may cause devastating morbidity and mortality.

Epidemiologic characteristics and risk factors for renal cell cancer

Incidence rates of renal cell cancer, which accounts for 85% of kidney cancers, have been rising in the United States and in most European countries for several decades. Family history is associated with a two- to four-fold increase in risk, but the major forms of inherited predisposition together account for less than 4% of renal cell cancers. Cigarette smoking, obesity, and hypertension are the most consistently established risk factors. Analgesics have not been convincingly linked with renal cell cancer risk. A reduced risk of renal cell cancer among statin users has been hypothesized but has not been adequately studied. A possible protective effect of fruit and vegetable consumption is the only moderately consistently reported dietary finding, and, with the exception of a positive association with parity, evidence for a role of hormonal or reproductive factors in the etiology of renal cell cancer in humans is limited. A recent hypothesis that moderate levels of alcohol consumption may be protective for renal cell cancer is not strongly supported by epidemiologic results, which are inconsistent with respect to the categories of alcohol consumption and the amount of alcohol intake reportedly associated with decreased risk. For occupational factors, the weight of the evidence does not provide consistent support for the hypotheses that renal cell cancer may be caused by asbestos, gasoline, or trichloroethylene exposure. The established determinants of renal cell cancer, cigarette smoking, obesity, and hypertension, account for less than half of these cancers. Novel epidemiologic approaches, including evaluation of gene–environment interactions and epigenetic mechanisms of inherited and acquired increased risk, are needed to explain the increasing incidence of renal cell cancer.

Biopsy of renal masses: when and why

Percutaneous image-guided biopsy of renal masses is a safe and accurate procedure. Although once reserved for the diagnosis of unresectable renal cell carcinoma, metastases, lymphoma, and infection, today percutaneous image-guided biopsy has an expanded role. There is increasing awareness that a substantial proportion of small, solid renal masses are benign neoplasms. Although imaging can be used to diagnose most of them, some are incorrectly believed to represent renal cell carcinoma and unnecessary surgery may be performed. Based largely on advances in cytological techniques, percutaneous biopsy can be now be used to diagnose benign neoplasms and thus prevent them from being treated unnecessarily. Concurrent advances in percutaneous ablation have also promoted its use. As a result, there are 8 established indications for percutaneous biopsy, and reason to believe that the number of indications will expand further in the future.

Lifestyle Factors, Exposures, Genetic Susceptibility, and Renal Cell Cancer Risk: A Review

Malignant kidney tumors account for approximately 2% of all new primary cancer cases diagnosed in the United States, with an estimated 30,000 cases occurring annually. Although a variety of agents, chemical and biological, have been implicated as causal agents in the development of renal cell carcinoma (RCC), the etiology remains enigmatic. The strongest association has been developed between cigarette smoking and renal cancer however consistent, positive associations between RCC and obesity, diabetes, and hypertension have also been reported. In addition, more recent investigations of familial kidney cancer syndromes indicate that a strong genetic component contributes to RCC development. Several genes have been identified through investigation of familial kidney cancer syndromes. This review article describes recent trends in RCC incidence and the currently identifiable etiological causes that account for approximately half of the RCC cases diagnoses. The remainder of this review then focuses on additional risk factors that have thus far not been well examined but may be helpful in explaining the increasing incidence trends and the geographic or racial variation observed nationally and worldwide.

Origin of renal cell carcinomas

Cancer is a heritable disorder of somatic cells: environment and heredity are both important in the carcinogenic process. The primal force is the "two hits" of Knudson's hypothesis, which has proved true for many tumours, including renal cell carcinoma. Knudson et al. [1, 2] recognised that familial forms of cancer might hold the key to the identification of important regulatory elements known as tumour-suppressor genes. Their observations (i.e., that retinoblastoma tend to be multifocal in familial cases and unifocal in sporadic presentation) led them to propose a two-hit theory of carcinogenesis. Furthermore, Knudson postulated that patients with the familial form of the cancer would be born with one mutant allele and that all cells in that organ or tissue would be at risk, accounting for early onset and the multifocal nature of the disease. In contrast, sporadic tumours would develop only if a mutation occurred in both alleles within the same cell, and, as each event would be expected to occur with low frequency, most tumours would develop late in life and in a unifocal manner [3, 4]. The kidney is affected in a variety of inherited cancer syndromes. For most of them, both the oncogene/tumour-suppressor gene involved and the respective germline mutations have been identified. Each of the inherited syndromes predisposes to distinct types of renal carcinoma. Families with hereditary predisposition to cancer continue to provide a unique opportunity for the identification and characterisation of genes involved in carcinogenesis. A surprising number of genetic syndromes predispose to the development of renal cell carcinoma, and genes associated with five of these syndromes have been already identified: VHL, MET, FH, BHD and HRPT2. Few cancers have as many different types of genetic predisposition as renal cancer, although to date only a small proportion of renal cell cancers can be explained by genetic predisposition.

A case of Birt-Hogg-Dubé syndrome

Birt-Hogg-Dubé syndrome (BHDS) is an autosomal dominant genodermatosis characterized by cutaneous hair follicle tumors (fibrofolliculoma or trichodiscoma), pulmonary cysts, and increased risk of renal neoplasia. The genetic alteration for BHDS has been mapped to chromosome 17p12q11, and the gene in this region has been cloned and believed to be responsible for the BHDS. Mutations in the BHD gene (also known as FLCN) have been described in the patients with BHDS. We present a case of a 30-yr-old Korean woman with multiple mildly pruritic papules on her face and neck area. The patient had several firm, flesh-colored, dome-shaped, papular lesions measuring between 2 to 5 mm. Except for a history of pneumothorax her medical records were not remarkable. Mutation analysis of the BHD gene was performed, and a novel deletion mutation (p.F519LfsX17 [c.1557delT]) causing truncation of the gene product, folliculin, was found in the exon 14. The actual incidence of BHDS is unknown, but it is most likely underdiagnosed. So it is imperative that doctors recognize the skin lesions of BHDS and institute proper screening to detect other manifestations of the disease. Here, we report a case of BHDS with a novel mutation, which is the first report in Korea.

Familial Syndromes Coupling with Small Renal Masses

During the past two decades, several new hereditary renal cancers have been discovered but are not yet widely known. Hereditary renal cancer syndromes can lead to multiple bilateral kidney tumors that occur at a younger age than that at which the nonhereditary renal cancers occur. The aim of our work is to review the features of hereditary renal cancers, the basic principles of genetic relevant to these syndromes, and the various histopathologic features of renal cancer. In addition, we will describe the known familial syndromes associated with small renal masses.

Clonal expansion of mutated mitochondrial DNA is associated with tumor formation and complex I deficiency in the benign renal oncocytoma

Mutations in mitochondrial DNA (mtDNA) are frequent in cancers but it is not yet clearly established whether they are modifier events involved in cancer progression or whether they are a consequence of tumorigenesis. Here we show a benign tumor type in which mtDNA mutations that lead to complex I (CI) enzyme deficiency are found in all tumors and are the only genetic alteration detected. Actually renal oncocytomas are homogeneous tumors characterized by dense accumulation of mitochondria and we had found that they are deficient in electron transport chain complex I (CI, NADH-ubiquinone oxidoreductase). In this work total sequencing of mtDNA showed that 9/9 tumors harbored point mutations in mtDNA, seven in CI genes, one in complex III, and one in the control region. 7/8 mutations were somatic. All tumors were somatically deficient for CI. The clonal amplification of mutated mtDNA in 8/9 tumors demonstrates that these alterations are selected and therefore favor or trigger growth. No nuclear DNA rearrangement was detected beside mtDNA defects. We hypothesize that functional deficiency of the oxidative phosphorylation CI could create a loop of amplification of mitochondria during cell division, impair substrates oxidation and increase intermediary metabolites availability.

Genetics and epigenetics of renal cell cancer

Renal cell carcinoma (RCC) is not a single disease, but comprises a group of tumors of renal epithelial origin, each with a different histology, displaying a different clinical course and caused by different genetic alterations. Since cure rates are inversely associated with stage and response to the available treatment regimes is limited to a subgroup of patients, diagnostic methods facilitating early detection and new therapeutic modalities are necessary. Increased knowledge of the underlying pathophysiology of RCC has resulted in the identification of genetic alterations involved in renal cell cancer carcinogenesis. Promising agents to target these pathways, especially the angiogenesis pathway, are being developed, some of which are already standard of care. In addition to genetics, knowledge on epigenetics in the process of renal tumorigenesis has been significantly increased in the last decades. Epigenetics will play an increasing role in the development of new therapeutic modalities and may deliver new prognostic and early diagnostic markers. In this review we discuss the background of RCC and the clinical applications of RCC genetics and epigenetics.

Polycystic kidneys: a cautionary story

We describe the imaging appearances of a patient with bilateral, synchronous, multiloculated renal cell carcinoma with a predominantly cystic nature. The patient had progressive chronic renal failure. He was initially erroneously diagnosed as having autosomal dominant polycystic kidney disease (ADPKD) on the basis of the imaging findings. We believe this to be the first report describing bilateral synchronous renal carcinomas replacing the renal parenchyma imitating ADPKD.

Role of the ubiquitin proteasome system in renal cell carcinoma

Renal cell carcinoma (RCC) accounts for approximately 2.6% of all cancers in the United States. While early stage disease is curable by surgery, the median survival of metastatic disease is only 13 months. In the last decade, there has been considerable progress in understanding the genetics of RCC. The VHL tumor suppressor gene is inactivated in the majority of RCC cases. The VHL protein (pVHL) acts as an E3 ligase that targets HIF-1, the hypoxia inducible transcription factor, for degradation by the ubiquitin proteasome system (UPS). In RCC cases with mutant pVHL, HIF-1 is stabilized and aberrantly expressed in normoxia, leading to the activation of pro-survival genes such as vascular endothelial growth factor (VEGF). This review will focus on the defect in the UPS that underlies RCC and describe the development of novel therapies that target the UPS.

Publication history: Republished from Current BioData's Targeted Proteins database (TPdb; ).

The morphologic spectrum of kidney tumors in hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome

Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) is an autosomal dominant familial syndrome characterized by the development of cutaneous and uterine leiomyomas as well as renal tumors. The mutation of this condition has been identified in the fumarate hydratase (FH, 1q42.3-q43) gene. The histology of the renal cancers has not been well described or illustrated because of the newness of the syndrome. We reviewed 40 renal tumors resected from 38 patients belonging to HLRCC families with proven fumarate hydratase germline mutation. Patients ranged in age from 17 to 75 years of age. Tumors were unilateral in all but 2 cases. The size of the tumors varied between 2.3 and 20 cm and there was no laterality preference. Several different architectural patterns were recognized: papillary (25 cases), tubulo-papillary (8 cases), tubular (2 cases), and solid (1 case). Mixed patterns were also present in 4 cases. The most important histologic feature of these neoplasms, which we believe to be the hallmark of the HLRCC tumors, is the presence of a characteristic large nucleus with a very prominent inclusion like orangiophilic or eosinophilic nucleolus, surrounded by a clear halo. Immunohistochemical studies did not provide a specific marker for these tumors, however, loss of heterozygosity at 1q32 and 1q42-44 was frequently found. These tumors are associated with poor prognosis and frequent spread to regional lymph nodes. At the moment, morphology is the best tool to recognize these tumors. Proper diagnosis of this syndrome by the pathologist may assist in early detection of these tumors.

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.