Familial renal oncocytoma: clinicopathological study of 5 families

Low grade oncocytic tumors of the kidney: a clinically relevant approach for the workup and accurate diagnosis

Renal oncocytoma and chromophobe renal cell carcinoma were accepted as unique renal tumors in the late 1990s. Since their formal description, criteria for diagnosis have evolved and additional distinct tumor subtypes originally considered as one these two entities are now recognized. The last two decades have witnessed unprecedented interest in the spectrum of low grade oncocytic renal neoplasms in three specific areas: (1) histologic characterization of tumors with overlapping morphologic features between oncocytoma and chromophobe renal cell carcinoma; (2) description of potentially unique entities within this spectrum, such as eosinophilic vacuolated tumor and low-grade oncocytic tumor; and (3) better appreciation of the association between a subset of low grade oncocytic tumors and hereditary renal neoplasia. While this important work has been academically rewarding, the proposal of several histologic entities with overlapping morphologic and immunophenotypic features (which may require esoteric adjunctive immunohistochemical and/or molecular techniques for confirmation) has created frustration in the diagnostic pathology and urology community as information evolves regarding classification within this spectrum of renal neoplasia. Pathologists, including genitourinary subspecialists, are often uncertain as to the "best practice" diagnostic approach to such tumors. In this review, we present a practical clinically relevant algorithmic approach to classifying tumors within the low grade oncocytic family of renal neoplasia, including a proposal for compressing terminology for evolving categories where appropriate without sacrificing prognostic relevance.

New developments in existing WHO entities and evolving molecular concepts: The Genitourinary Pathology Society (GUPS) update on renal neoplasia

The Genitourinary Pathology Society (GUPS) reviewed recent advances in renal neoplasia, particularly post-2016 World Health Organization (WHO) classification, to provide an update on existing entities, including diagnostic criteria, molecular correlates, and updated nomenclature. Key prognostic features for clear cell renal cell carcinoma (RCC) remain WHO/ISUP grade, AJCC/pTNM stage, coagulative necrosis, and rhabdoid and sarcomatoid differentiation. Accrual of subclonal genetic alterations in clear cell RCC including SETD2, PBRM1, BAP1, loss of chromosome 14q and 9p are associated with variable prognosis, patterns of metastasis, and vulnerability to therapies. Recent National Comprehensive Cancer Network (NCCN) guidelines increasingly adopt immunotherapeutic agents in advanced RCC, including RCC with rhabdoid and sarcomatoid changes. Papillary RCC subtyping is no longer recommended, as WHO/ISUP grade and tumor architecture better predict outcome. New papillary RCC variants/patterns include biphasic, solid, Warthin-like, and papillary renal neoplasm with reverse polarity. For tumors with 'borderline' features between oncocytoma and chromophobe RCC, a term "oncocytic renal neoplasm of low malignant potential, not further classified" is proposed. Clear cell papillary RCC may warrant reclassification as a tumor of low malignant potential. Tubulocystic RCC should only be diagnosed when morphologically pure. MiTF family translocation RCCs exhibit varied morphologic patterns and fusion partners. TFEB-amplified RCC occurs in older patients and is associated with more aggressive behavior. Acquired cystic disease (ACD) RCC-like cysts are likely precursors of ACD-RCC. The diagnosis of renal medullary carcinoma requires a negative SMARCB1 (INI-1) expression and sickle cell trait/disease. Mucinous tubular and spindle cell carcinoma (MTSCC) can be distinguished from papillary RCC with overlapping morphology by losses of chromosomes 1, 4, 6, 8, 9, 13, 14, 15, and 22. MTSCC with adverse histologic features shows frequent CDKN2A/2B (9p) deletions. BRAF mutations unify the metanephric family of tumors. The term "fumarate hydratase deficient RCC" ("FH-deficient RCC") is preferred over "hereditary leiomyomatosis and RCC syndrome-associated RCC". A low threshold for FH, 2SC, and SDHB immunohistochemistry is recommended in difficult to classify RCCs, particularly those with eosinophilic morphology, occurring in younger patients. Current evidence does not support existence of a unique tumor subtype occurring after chemotherapy/radiation in early childhood.

FLCN: The causative gene for Birt-Hogg-Dubé syndrome

Germline mutations in the novel tumor suppressor gene FLCN are responsible for the autosomal dominant inherited disorder Birt-Hogg-Dubé (BHD) syndrome that predisposes to fibrofolliculomas, lung cysts and spontaneous pneumothorax, and an increased risk for developing kidney tumors. Although the encoded protein, folliculin (FLCN), has no sequence homology to known functional domains, x-ray crystallographic studies have shown that the C-terminus of FLCN has structural similarity to DENN (differentially expressed in normal cells and neoplasia) domain proteins that act as guanine nucleotide exchange factors (GEFs) for small Rab GTPases. FLCN forms a complex with folliculin interacting proteins 1 and 2 (FNIP1, FNIP2) and with 5' AMP-activated protein kinase (AMPK). This review summarizes FLCN functional studies which support a role for FLCN in diverse metabolic pathways and cellular processes that include modulation of the mTOR pathway, regulation of PGC1α and mitochondrial biogenesis, cell-cell adhesion and RhoA signaling, control of TFE3/TFEB transcriptional activity, amino acid-dependent activation of mTORC1 on lysosomes through Rag GTPases, and regulation of autophagy. Ongoing research efforts are focused on clarifying the primary FLCN-associated pathway(s) that drives the development of fibrofolliculomas, lung cysts and kidney tumors in BHD patients carrying germline FLCN mutations.

[Hereditary renal tumors: More common than expected?]

Renal cell carcinomas are associated with hereditary tumor syndromes in approximately 5 % of cases. In patients with a hereditary predisposition, tumors show an earlier age of onset, often with a multicentric and bilateral manifestation. While some patients with renal cell carcinoma can be classified into well-characterized kidney cancer syndromes others have a genetic background which is still poorly understood. Most of the specific tumor syndromes are associated with a histopathologically distinct renal cell tumor phenotype. The recognition of patients with hereditary renal cell carcinoma and the identification of individual family members with a higher risk of development of renal tumors is important for early tumor detection and treatment. This manuscript reviews the clinical pathological and molecular findings of hereditary renal cell carcinoma syndromes.

Molecular genetics and clinical features of Birt-Hogg-Dubé syndrome

Birt-Hogg-Dubé (BHD) syndrome is an inherited renal cancer syndrome in which affected individuals are at risk of developing benign cutaneous fibrofolliculomas, bilateral pulmonary cysts and spontaneous pneumothoraces, and kidney tumours. Bilateral multifocal renal tumours that develop in BHD syndrome are most frequently hybrid oncocytic tumours and chromophobe renal carcinoma, but can present with other histologies. Germline mutations in the FLCN gene on chromosome 17 are responsible for BHD syndrome--BHD-associated renal tumours display inactivation of the wild-type FLCN allele by somatic mutation or chromosomal loss, confirming that FLCN is a tumour suppressor gene that fits the classic two-hit model. FLCN interacts with two novel proteins, FNIP1 and FNIP2, and with AMPK, a negative regulator of mTOR. Studies with FLCN-deficient cell and animal models support a role for FLCN in modulating the AKT-mTOR pathway. Emerging evidence links FLCN with a number of other molecular pathways and cellular processes important for cell homeostasis that are frequently deregulated in cancer, including regulation of TFE3 and/or TFEB transcriptional activity, amino-acid-dependent mTOR activation through Rag GTPases, TGFβ signalling, PGC1α-driven mitochondrial biogenesis, and autophagy. Currently, surgical intervention is the only therapy available for BHD-associated renal tumours, but improved understanding of the FLCN pathway will hopefully lead to the development of effective forms of targeted systemic therapy for this disease.

Clinical Features, Genetics and Potential Therapeutic Approaches for Birt-Hogg-Dubé Syndrome

INTRODUCTION

Birt-Hogg-Dubé (BHD) syndrome is an autosomal dominant disorder that predisposes to fibrofolliculomas, pulmonary cysts, spontaneous pneumothorax and renal neoplasia. BHD is characterized by germline mutations in tumor suppressor FLCN. Inactivation of the remaining FLCN allele in kidney cells drives tumorigenesis. Novel FLCN-interacting proteins, FNIP1 and FNIP2, were identified. Studies with FLCN-deficient in vitro and in vivo models support a role for FLCN in modulating AKT-mTOR signaling. Emerging evidence suggests that FLCN may interact in a number of pathways/processes. Identification of FLCN's major functional roles will provide the basis for developing targeted therapies for BHD patients.

AREAS COVERED

This review covers BHD diagnostic criteria, clinical manifestations and genetics, as well as molecular consequences of FLCN inactivation. Recommended surveillance practices, patient management, and potential therapeutic options are discussed.

EXPERT OPINION

In the decade since FLCN was identified as causative for BHD, we have gained a greater understanding of the clinical spectrum and genetics of this cancer syndrome. Recent studies have identified interactions between FLCN and a variety of signaling pathways and cellular processes, notably AKT-mTOR. Currently, surgical intervention is the only available therapy for BHD-associated renal tumors. Effective therapies will need to target primary pathways/processes deregulated in FLCN-deficient renal tumors and fibrofolliculomas.

Renal cell carcinoma : clinical features and management

In 1999 it was estimated that renal cell carcinoma (RCC) would account for 29,990 new cancer cases diagnosed in the United States (61% in men and 39% in women), and lead to 11,600 deaths. RCC accounts for 2-3% of all malignancies in adults and causes 2.3% of all cancer deaths in the United States annually (1). Approx 4% of all RCC cases are bilateral at some point in the life of the patient. Data from over 10,000 cases of renal cancer entered in the Connecticut Tumor Registry suggests an increase in the incidence of renal cancer from 1935-1989; in women the incidence increased from 0.7 to 4.2 in 100,000, and in men from 1.6 to 9.6 in 100,000 (2). Factors implicated in the development of RCC include cigarette smoking, exposure to petroleum products, obesity, diuretic use, cadmium exposure, and ionizing radiation (3-9).

Genetic syndromes associated with renal cell carcinoma: a review

AIMS

A review of recent knowledge on heredital syndromes related to renal cell carcinoma.

METHODS

Aim of this review was to summarize the recent knowledge of genetic syndromes associated with renal cell carcinoma.

RESULTS

Summary of incidence and factors modulating risk of hereditary renal cell carcinoma development.

CONCLUSIONS

Hereditary forms of RCC are relatively rare. Their study is beneficial in many ways. In individuals at a higher risk of a hereditary syndrome, the knowledge of hereditary forms may help to significantly decrease the impact of the hereditary disease. In the general population, knowledge acquired by the study of hereditary forms of RCC may in the future contribute to both diagnosis and treatment of sporadic tumours.

The impact of germline BHD mutation on histological concordance and clinical treatment of patients with bilateral renal masses and known unilateral oncocytoma

PURPOSE

Managing oncocytoma in the setting of bilateral renal masses is a challenging scenario. Nevertheless, to our knowledge the pathological concordance of an oncocytic neoplasm in 1 kidney with tumors in the contralateral kidney is not known. We evaluated the influence of germline Birt-Hogg-Dubé mutation on concordance rates to assist in managing these cases.

MATERIALS AND METHODS

We reviewed the records of patients at the National Institutes of Health between 1983 and 2009 who had bilateral renal masses, known pathology bilaterally and oncocytoma or an oncocytic neoplasm in at least 1 kidney. Oncocytoma or an oncocytic neoplasm in 2 renal units was considered concordant. Demographic, pathological and clinical data were collected.

RESULTS

The population consisted of 40 patients, including 23 with and 17 without a diagnosis of Birt-Hogg-Dubé syndrome. Patients with the syndrome were younger (p <0.01) but there were no other differences between the 2 groups. However, patients with the syndrome had statistically lower histological concordance between bilateral masses than patients without the diagnosis (Fisher's exact test p <0.01). Also, the 8 patients without Birt-Hogg-Dubé syndrome who had multifocal renal masses showed 100% oncocytoma concordance between renal units.

CONCLUSIONS

Of patients with bilateral renal masses those with Birt-Hogg-Dubé syndrome have significantly lower histological concordance than those without the syndrome. Patients with Birt-Hogg-Dubé syndrome should be monitored and treated differently than those without detected genetic mutations, especially patients with multifocal oncocytomas. Genetic testing for Birt-Hogg-Dubé should be considered in the treatment algorithm of patients with bilateral renal masses and known oncocytoma.

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.

Genetic profiles in renal tumors

Renal cell carcinoma in adult comprises a heterogeneous group of tumors with variable clinical outcomes, which ranges from indolent to aggressively malignant. The application of molecular genetics techniques to the study of renal neoplasms has resulted in improved classification of these entities and better understanding of biological mechanisms responsible for tumor development and progression. In the present article we review the molecular genetic profiles of different renal cell tumors and discuss their relevance to the carcinogenesis mechanisms and to the clinical diagnosis of renal cell carcinoma. Understanding of the molecular genetics of renal tumors is beneficial in making accurate diagnoses, assessing prognoses, and selecting appropriate and targeted therapeutic options.

Ultrastructural Studies in a Series of 18 Cases of Chromophobe Renal Cell Carcinoma

Chromophobe renal cell carcinoma (CRCC) is a distinct variant of renal epithelial neoplasm. Ultrastructurally, the presence of numerous cytoplasmic microvesicles is highly characteristic of CRCC, as are mitochondria with tubulovesicular cristae. All 18 cases is this study present these two elements with a different distribution, depending on the morphological variant (typìcal or eosinophilic). In both variants, the mitochondria show tubulovesicular cristae and budding from the outer mitochondrial membrane that is very similar to the cytoplasmic microvesicles. An association was also found between intracristal mitochondrial swelling and bud formation. These buds, when detached from the mitochondrial membrane, may convert into the cytoplasmic microvesicles.

Renal Oncocytoma in Taiwan

BACKGROUND

Renal oncocytoma has been repeatedly reported in Western countries, but only a few cases have been reported in Eastern countries. This study aims to review the clinical course of renal oncocytoma in an Eastern country such as Taiwan.

MATERIALS AND METHODS

Sixteen cases of renal oncocytoma seen between 1987 and 2002 at Chang Gung Memorial Hospital, Taipei, Taiwan, were studied.

RESULTS

Preoperatively, all patients were diagnosed to have renal cell carcinoma, following various radiologic studies. Perioperatively, frozen sections of three patients indicated renal oncocytoma in two and renal cell carcinoma in one. Renal oncocytoma has marked similarities to renal cell carcinoma, according to various radiologic, cytologic, and pathological investigations, so an accurate diagnosis is difficult to achieve, either preoperatively or perioperatively. Therefore, rather than being treated with partial nephrectomy, all patients were treated aggressively with unilateral radical nephrectomy. Postoperatively, all 16 patients were followed up, from 12 to 189 months, with a mean of 58.7 months. Notably, all patients survived with no evidence of tumor recurrence.

CONCLUSIONS

The experience in Taiwan is generally that renal oncocytoma behaves benignly, as reported in other areas. The excellent prognosis associated with this tumor appears to indicate that partial nephrectomy may suffice for removing the tumor, while sparing other unaffected renal parenchyma.

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.

2009 update on the classification of renal epithelial tumors in adults

The classification of kidney tumors in adults expands rapidly with new categories recently incorporated. This will result in the modification of the current 2004 World Health Organization (WHO) classification of the adult renal epithelial neoplasms. Emphasis should be placed in defining risk groups categorized as malignant or benign tumors, including a category of tumors with low malignant potential to accommodate recently recognized categories with extremely good prognosis after surgery. Unusual tumors such as familial renal cell carcinoma (RCC), translocation RCC, renal cell carcinoma after neuroblastoma, tubular mucinous and spindle cell carcinoma, and mixed epithelial and stromal tumors are also presented. A number of recently described entities and morphologic variants of classical categories deserve recognition since they can be important in differential diagnosis. This review emphasizes clinical, pathological and genetic features defining renal epithelial tumors in adults.

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.

Chromophobe renal cell carcinoma: histomorphologic characteristics and evaluation of conventional pathologic prognostic parameters in 145 cases

The aggregate literature suggests that chromophobe renal cell carcinoma (RCC) is biologically a tumor of low malignant potential with reported 5-year and 10-year survival rates of 78% to 100% and 80% to 90%, respectively. The conventional prognostic parameters that determine the outcome of the tumors that progress remain to be fully characterized. Clinicopathologic features of 145 cases were correlated with outcome. The mean age of the patients was 59 years (range, 27 to 82) and the male to female ratio was 1.1:1. Most tumors were well circumscribed and averaged 8.0 cm (range, 1.0 to 30.0 cm); multifocality and bilaterality were present in 8% and 3% of patients. Sixty (41%) were eosinophilic variant (greater than 80% eosinophilic cells), 18 (12%) were classic type (greater than 80% pale cells), and 67 (46%) were mixed (containing variable admixture of pale and eosinophilic cells). A subset of eosinophilic chromophobe RCC contained or had areas similar to renal oncocytomas. These tumors tended to be more commonly bilateral (11%) and multifocal (22%) and were not associated with necrosis or sarcomatoid change. Sarcomatoid change was present in 12/145 (8%) tumors. By histologic grade, 1%, 19%, 74%, 6% were Fuhrman nuclear grade 1, 2, 3, and 4. Nineteen percent, 21%, 28%, 13%, 4%, 1%, and 3% were pT (2002) stage pT1a, pT1b, pT2, pT3a, pT3b, pT3c, and pT4 tumors. Two percent tumors were pN1 at presentation and 2.8% tumors were M1 at presentation. Follow-up (1 to 182 mo, mean 48 mo, median 37 mo) was available in 123 cases. Disease progression (local recurrence 4, metastasis 15, and/or death 10) was seen in 20 patients. In univariable analysis, tumor size (P=0.025), pT stage (P<0.001), broad alveolar architecture (P=0.012), Fuhrman nuclear grade (P<0.001), microscopic tumor necrosis (P=0.001), vascular invasion (P=0.020), and sarcomatoid change (P< or =0.001) were associated with progression. A multivariable Cox regression model revealed sarcomatoid change (P=0.013, estimated relative hazard 4.7), microscopic necrosis (P=0.020, relative hazard=3.5), and pT stage (P=0.025, relative hazard 3.4) as independent predictors of aggressive chromophobe RCC. Although the large majority of chromophobe RCCs have a favorable prognosis, a distinct subset of patients progress. The pT stage of tumor, tumor necrosis, and sarcomatoid change all predict aggressive phenotype of chromophobe RCC. The adverse presence of these features in a nephrectomy specimen with chromophobe RCC warrants active surveillance, and these patients may be candidates for adjuvant therapies as they become available.

Renal oncocytoma: clinical experience of Taipei Veterans General Hospital

BACKGROUND

Renal oncocytoma has been reported mostly in the Western literature, and only a few cases have been reported in Eastern populations. In the present study, we review the clinical course of renal oncocytoma in our institution.

METHODS

We obtained the files of 13 cases of renal oncocytoma between 1988 and 2006 from the pathological archives of Taipei Veterans General Hospital. We retrospectively analyzed the patients' characteristics, clinical manifestations, surgical technique and clinical outcome.

RESULTS

The study population comprised 10 men and 3 women, and the mean age at diagnosis was 59.6 years (range, 37-75 years). Twelve patients (92%) were asymptomatic at presentation and were incidentally diagnosed to have renal tumor by sonography (9 patients), computed tomography (1 patient) or magnetic resonance imaging (2 patients), and 1 presented with hematuria. The clinical impression of oncocytoma was made preoperatively in only 3 patients by imaging studies, and most of the patients (76.9%) were diagnosed with renal cell carcinoma before surgery. Ten were treated with radical nephrectomy, 2 with partial nephrectomy, and 1 received excisional biopsy. All patients had unilateral solitary renal tumor; the right kidney was involved in 7 cases (54%) and the left in 6 (46%). Mean tumor size was 5.3 cm (range, 2.7-8.5 cm). Three patients were lost to follow-up in our series, and there was no recurrence or death (100% disease-specific survival) in the remaining 10 patients (77%) who were followed-up for a mean duration of 53.2 months (range, 10-117 months).

CONCLUSION

Renal oncocytoma has a benign clinical course with excellent long-term outcomes. Currently, nephron-sparing surgery is the mainstay of treatment, especially in patients with small tumors. However, accurate preoperative diagnosis based only on imaging studies is difficult, and radical nephrectomy was performed for most of the patients in our series.

Familial Renal Carcinoma: Clinical Evaluation, Clinical Subtypes and Risk of Renal Carcinoma Development

PURPOSE

Familial renal carcinoma is defined as families with 2 or more individuals with renal cell carcinoma without evidence of known hereditary renal carcinoma syndromes. To better characterize this familial cancer we reviewed renal carcinoma families evaluated at the National Cancer Institute between 1990 and 2004 to identify distinctive features of these families. We also determined the risk of renal carcinoma in first-degree relatives of affected family members.

MATERIALS AND METHODS

We evaluated 141 at risk asymptomatic relatives of affected individuals from 50 families with 2 or more members with renal carcinoma. Histology slides of renal tumors from affected family members were reviewed. At risk members from renal carcinoma families were screened for occult renal neoplasms by renal ultrasound and computerized tomography. DNA from select families was tested for germline mutations of known renal carcinoma genes when clinically indicated and constitutional cytogenetic analysis was performed to search for germline chromosome alterations.

RESULTS

Familial renal carcinoma families could be subdivided into subtypes based on tumor multiplicity and renal tumor histology. Of 141 at risk members of renal carcinoma families screened for occult renal tumors 2 were found to have occult renal tumors, which were identified as renal oncocytoma and a solid tumor that was not resected, respectively. No histologically confirmed occult renal carcinomas were detected in at risk family members. Several families previously classified as having familial renal carcinoma were found on further evaluation to have hereditary renal cancer syndromes.

CONCLUSIONS

Familial renal carcinoma is a heterogeneous clinical and pathological entity. Familial renal carcinoma was subdivided into groups based on tumor multiplicity and tumor pathology. The empirical risk of histologically documented renal carcinoma in first-degree relatives who were members of familial renal carcinoma families was less than 1:141. One renal oncocytoma and 1 small solid renal tumor were detected.

[WHO classification 2004: tumors of the kidneys]

New entities, confirmed either by cytogenetic findings or by new molecular markers, have been included in the WHO 2004 renal tumor classification. Moreover, imaging improvements provide a better radiologic description of tumors. In this article, we will discuss the WHO 2004 classification and focus on the new entities and their macroscopic appearance. We will especially insist on the following entities: multilocular clear cell renal carcinoma, Xp11 translocation carcinoma, low-grade mucinous tubular carcinoma, epithelioid angiomyolipoma, and benign mixed epithelial and stromal tumor. We also discuss the new concept of hybrid oncocytoma and chromophobe renal cell carcinoma, as well as the Birt-Hogg-Dube syndrome, which is associated with kidney tumors.

Natural history of the Nihon (Bhd gene mutant) rat, a novel model for human Birt–Hogg–Dubé syndrome

In the Nihon rat, an established model of hereditary renal cell carcinoma (RCC), the propensity for tumor development, is inherited as an autosomal dominant trait due to a single germline nucleotide insertion mutation in the rat Bhd ortholog. The Birt-Hogg-Dubé (BHD) syndrome is a rare autosomal dominant disease characterized by fibrofolliculoma, pulmonary cysts, spontaneous pneumothorax, and renal neoplasm. The renal lesions of the Nihon rat are characterized, and extrarenal lesions are also described in this work. The earliest lesion of the RCC was identified as an altered tubule at as early as 3 weeks of age and rapidly progressed through adenoma to carcinoma with the primary cell type being clear/acidophilic where some similarities were evident to RCCs in BHD syndrome. The Nihon rats demonstrate a heterotopic ossification within RCCs and three extrarenal lesions, clear cell hyperplasia/adenoma of the endometrium, clear cell change of the epithelium of striated portions of salivary glands, and cardiac rhabdomyomatosis. This rat model of hereditary RCC provides a useful tool for analyzing the series of events leading to renal tumorigenesis and for studying BHD gene functions.

2004 WHO classification of the renal tumors of the adults

BACKGROUND

The recently introduced 2004 World Health Organisation (WHO) classification of the adult renal epithelial neoplasms is meant to replace the previous 1998 WHO classification.

METHODS AND RESULTS

The 2004 WHO classification is based on pathology and genetic abnormalities. The description of categories has been expanded to improve their recognition and new diagnostic categories are included. Emphasis has been placed on defining familial renal cancer, carcinoma associated with Xp11 translocations, carcinoma associated with neuroblastoma, multilocular cystic renal cell carcinoma, tubular, mucinous and spindle cells carcinoma; and mixed epithelial and stromal tumour. The potentially aggressive epithelioid angiomyolipoma is recognised.

CONCLUSIONS

Recognising these categories may have important implications in patients' clinical management.

Multifocal renal oncocytoma in a patient with Von Hippel-Lindau mutation

Von Hippel-Lindau disease (VHL) is a rare genetic disease with a lifetime risk of clear cell renal cell carcinoma in approximately 70% of cases. We present a case of a 63-year-old man with bilateral, multifocal renal masses. Genetic testing results were consistent with a VHL deletion. The patient had no other disease manifestations consistent with VHL. The patient underwent staged bilateral nephron-sparing procedures. Pathology of all renal masses revealed oncocytoma. To our knowledge, we describe the first reported case of multiple renal oncocytomas in a male patient with a germline VHL mutation.

Follow-up of renal oncocytoma diagnosed by percutaneous tumor biopsy

OBJECTIVES

To evaluate the outcome of patients with oncocytoma of the kidney diagnosed in our center by percutaneous biopsy and treated with watchful waiting.

METHODS

From January 1998 to April 2004, of 148 solid renal tumors biopsied in our center, 15 were renal oncocytomas. The mean (+/- standard deviation) follow-up was 30 +/- 19.8 months. We report on the outcome of these patients.

RESULTS

The mean age at diagnosis was 57.6 +/- 14.4 years, and mean tumor size was 3.49 +/- 2.43 cm, corresponding to a mean tumor volume of 62.3 +/- 135.4 cm3. During follow-up, 6 of 15 patients needed surgery: two partial and four total nephrectomies. Indications for surgery were initial tumor burden, greater than 0.5 cm/yr tumor growth, and patient's preference in 1 case, 4 cases, and 1 case, respectively. The patients who received surgical treatment were significantly younger (45.5 +/- 11.1 years versus 65.6 +/- 10.3 years) and had more bulky tumors at diagnosis (50 +/- 30.1 mm versus 27.3 +/- 10.5 mm). In 1 patient, a chromophobic renal cell carcinoma was associated with the oncocytoma. All 9 patients who did not receive surgical treatment remained asymptomatic.

CONCLUSIONS

The evolution of renal oncocytoma seems to be increase of tumor size with variable velocity. Treatment must be conservative. Initial management might be nonsurgical with close follow-up. Monitoring should not miss the time of conservative surgery. Initial tumor volume or fast tumor growth are indications for surgery. Partial nephrectomy, if the tumor size and localization are reasonable, is currently the technique of choice.

[Tumors of the kidneys: new entities]

Since 1998 new entities have surfaced in renal tumor classification and have been included in the WHO 2004 classification. In this article, we will discuss the following entities: multilocular clear cell renal carcinoma, Xp11 translocation carcinoma, low grade mucinous tubular carcinoma, epithelioid angiomyolipoma, benign mixed epithelial and stromal tumor. We will investigate new concepts of hybrid oncocytoma and chromophobe renal cell carcinoma and the syndrome of Birt-Hogg-Dube which is associated to kidney tumors. At least, we will touch on new elements in the Bellini carcinoma definition.

Mutational analysis of the rhodopsin gene in Chinese ADRP families by conformation sensitive gel electrophoresis

Retinitis pigmentosa is a very heterogeneous group of retinal degenerations, with multiple genes identified in each mode of inheritance. For autosomal dominant retinitis pigmentosa (ADRP), the most common gene is the rhodopsin (RHO) gene, mutations in which contribute to about 25% of ADRP in Caucasian population. To investigate the frequency and pattern of RHO point mutations in Chinese patients with ADRP, we have screened the five coding exons and splice sites of the RHO gene in 50 unrelated probands from Chinese ADRP families and 100 normal controls to identify disease-associated mutations, using conformation sensitive gel electrophoresis (CSGE) and direct DNA sequencing. Two RHO mutations, Pro347Leu and Pro327 (1-bp del), were identified each in one family, thus the frequency of RHO mutations among ADRP families in this study is less than 14% (2/50=4%, 95% confidence interval: 1-14%), lower than that in Europe and North America, which may reflect an ethnic difference between Chinese and Caucasian populations. Loss of all phosphorylation sites at the C-terminus and a highly conserved sequence QVS(A)PA may occur because of Pro327(1-bp del). CSGE was found to be a sensitive, simple and practical method for the screening of a large number of samples under highly reproducible conditions, and could be utilized in routine molecular diagnostic laboratories.

Molecular genetics of familial renal cell carcinoma syndromes

RCC represents a group of clinically and genetically diverse diseases. Familial RCC syndromes, although rare, provide an invaluable model to study the molecular mechanisms of renal carcinogenesis. Many causative oncogenes and tumor suppressor genes have been identified and it is now possible to identify the affected individuals and carriers by genetic testing. Understanding of the molecular pathways of these genes will have a significant impact on the diagnosis and treatment of familial and sporadic RCC.

Hereditary cancer syndromes of the skin

Hereditary cancer syndromes are a group of disorders characterized by a genetic susceptibility to the development of malignant tumors. Multiple cancers in the family or an abnormally early onset for the given cancer may suggest an underlying inherited predisposition. Awareness of their associated dermatologic manifestations can facilitate early detection of risk for neoplasms. This article provides an update on the clinical features, diagnostic criteria, and the use of genetic analysis in the detection of causative mutations of those hereditary cancer syndromes with cutaneous manifestations.

The genetics of renal oncocytosis: a possible modelfor neoplastic progression

Renal oncocytosis is a rare condition characterized by the presence of numerous oncocytomas and oncocytic changes in the renal tubules. Other than oncocytomas associated with the Birt-Hogg-Dube (BDH) syndrome, the genetics of oncocytosis is not known. Whether oncocytomas and oncocytosis are similar to BDH syndrome, in which the tumors diploid (as most oncocytomas are), or show chromosomal losses may be significant regarding the observation that in oncocytosis, there frequently is morphological evidence of progression to chromophobe carcinoma. Here we report on the case of a 69-year old male who underwent a staged procedure of partial nephrectomy on the left side and right radical nephrectomy for multiple renal tumors. The tumors were studied by routine hematoxylin and eosin morphology, immunohistochemistry, cytogenetics, and loss of heterozygosity analysis. Both kidneys had numerous oncocytic neoplasms morphologically progressing from oncocytomas to hybrid tumors with chromophobe carcinoma. Genetic studies demonstrated progression from normal cytogenetics to chromosomal losses similar to those in some oncocytomas and in chromophobe carcinomas. The genetics of this apparently nonfamilial oncocytoma differs from that of BDH syndrome and is characterized by losses involving chromosomes 1, 14, 21, and Y. To our knowledge, this is the first report of the genetic and cytogenetic findings in oncocytosis not related to BDH syndrome and may suggest a possible model of progression from oncocytoma to chromophobe renal cell carcinoma.

Renal oncocytosis presenting in childhood: a case report

Renal oncocytosis is a rare condition in which a spectrum of oncocytic lesions, including oncocytomas, diffusely involve the kidney. Few cases have been reported and all were in adult patients. We report here such a case in a 12-year-old girl. In addition to the unusual age at presentation, this case is remarkable for its heterogeneous tumor morphology, with some areas containing chromophobe carcinoma-like cells. Electron microscopy, immunohistochemistry, Hale's colloidal iron staining, and cytogenetics were performed to further evaluate the different morphologic areas. Our results suggest that the cells in the chromophobe carcinoma-like areas do not fulfill all the diagnostic criteria of chromophobe carcinoma. We caution pathologists in making a malignant diagnosis in such cases, especially in younger patients.

A medical oncologist's approach to immunotherapy for advanced renal tumors: is nephrectomy indicated?

Metastatic renal cell carcinoma is highly resistant to systemic therapy. Although interleukin-2 and interferon remain the most active agents for this disease, long-term survival rates remain poor. Two phase 3 trials, European Organization Research and Treatment of Cancer 30947 and Southwest Oncology Group 8949, have demonstrated a survival benefit of nephrectomy followed by interferon versus interferon alone in patients having an excellent performance status (PS 0 and 1). Removal of the primary tumor followed by interferon is not recommended for patients with a moderate or poor PS (PS 2-4). Even with this aggressive approach, most patients eventually will die from their kidney cancer; therefore, every patient with metastatic disease should be considered for enrollment into clinical trials.

The Hereditary Renal Cancer Syndromes

Although the majority of renal cell carcinomas (RCC) are sporadic, hereditary types of kidney cancer such as Von Hippel-Lindau (VHL) disease and hereditary papillary renal carcinoma syndromes are thought to account for approximately 4% of kidney cancers. A germline mutation seems to predispose to the development of specific histologic types of RCC. Hereditary kidney cancers are bilateral multifocal kidney tumors that, in some instances, occur at a younger age than do sporadic renal cancers.

A better knowledge of the genetic basis of renal carcinogenesis has been useful in identifying genetic causes of renal tumorigenesis, such as inactivation of the VHL tumor suppressor gene in clear cell carcinoma. Moreover, the genes responsible for hereditary renal cancer syndromes seems to play a role in the development of sporadic counterparts. Knowledge of genetic cancer syndromes may allow clinicians to screen and counsel family members, identify those patients at risk for multiple cancer development, and give the chance to intervene therapeutically when cancers are still treatable by identifying localized tumors through early screening. This article reviews the current status and recent advances in the field of familial kidney cancer syndromes.

The Genetic Basis of Cancer of the Kidney

PURPOSE

The types of epithelial renal tumors are clear cell, types I and II papillary, chromophobe and oncocytoma. We identified the genetic basis of these different types of kidney cancer to provide better methods for early diagnosis of this disease as well as provide the foundation for the development of molecular therapeutic approaches.

MATERIALS AND METHODS

To identify the genetic basis of kidney cancer we studied families with an inherited predisposition to kidney cancer. Families in which 2 or more individuals had kidney cancer underwent a comprehensive evaluation to determine whether they were affected with a hereditary form of renal carcinoma. Genetic linkage analysis was performed to identify the gene for inherited forms of renal carcinoma.

RESULTS

The gene for the inherited form of clear cell renal carcinoma associated with von Hippel-Lindau gene was identified. This gene has been found to be a tumor suppressor gene. A new form of inherited renal carcinoma, hereditary papillary renal carcinoma, was identified. The gene for this condition was identified and found to be the proto-oncogene c-Met. A previously unidentified form of familial renal oncocytoma was found. A familial form of chromophobe renal carcinoma and oncocytoma associated with Birt Hogg Dubé syndrome was found. The gene for this condition was localized on the short arm of chromosome 17 and it has been identified. We studied families with cutaneous leiomyomas, uterine leiomyomas and papillary renal carcinoma. We identified mutations in the fumarate hydratase gene in patients affected with this disorder, namely hereditary leiomyoma renal cell carcinoma.

CONCLUSIONS

Kidney cancer used to be considered a single disease. It is now known that there are a number of different types of cancers of the kidney with different histological patterns and different clinical courses that appear to respond differently to therapy. These different types of kidney cancer are caused by different genes, ie they each have a distinct genetic basis. Understanding the molecular pathways of these cancer genes should provide insight into their varying clinical courses and responses to treatment as well as provide the foundation for the development of disease specific molecular therapeutic strategies.

Hereditary kidney cancer

Significant advances have been made in the understanding of the genetic basis of familial renal neoplasia. Identification of key genes in the pathogenesis of various hereditary renal cancer syndromes has provided opportunities to screen family members at risk and to explore the significance of these genetic abnormalities in the development and genesis of much more common sporadic counterparts. As researchers continue to delineate critical carcinogenic pathways and accumulate expansive knowledge on oncogenic mechanisms driving cancer initiation and progression at the cellular and molecular levels, this information will be integrated and translated into effective diagnostic and therapeutic strategies that will dictate clinical management of all renal cancers.

Birt-Hogg-Dubé syndrome: A review of the literature and the differential diagnosis of firm facial papules

Birt-Hogg-Dubé syndrome (BHDS) was originally described in 1977 as the grouping of 3 skin tumors-the fibrofolliculoma, trichodiscoma, and acrochordon-in family members with an autosomal dominant inheritance pattern. In recent years it has become clear that these 3 lesions likely represent only 1 of these tumors, the fibrofolliculoma. More important, evidence now supports a definite susceptibility to malignant renal tumors and pulmonary disease in patients with BHDS. Clinical recognition of this entity is possible in spite of the fact that several syndromes exist that are characterized by the presence of multiple firm facial papules. We will discuss the evolution of BHDS from the original description to the recent discovery of the genetic susceptibility locus, illustrate the clinical differential diagnosis, and highlight the workup needed for newly diagnosed patients and their family members.

Imaging of hereditary renal cancer

Over the past 5 years there have been dramatic developments in the extent of knowledge of hereditary renal cancers. In addition to VHL, which is associated with clear cell carcinoma, one can now list HPRC (associated with type I papillary renal cancer) and HLRCC (associated with type II papillary renal cancer). BHD and FRO are associated with chromophobe carcinoma and oncocytomas, although other histologic tumor types have been found in BHD. Medullary carcinoma of the kidney is associated with sickle cell trait. Although the genes associated with these tumors have been discovered, the exact mechanisms by which they cause renal cancer remain to be elucidated. It is quite likely that other genes also are involved in this process. Using VHL as an example, research is now underway on targeting mutant pVHL or excess HIF for diagnostic and therapeutic purposes. Understanding the mechanisms leading to cancer may open new targets of opportunity for drug development. This improved knowledge of the biogenetic pathways used to form tumors will impact the development of new therapeutic techniques for treating renal cancers in hereditary and nonhereditary forms of the disease.

The genetic basis of renal cell carcinoma

The recognition of hereditary forms of renal cancer and the development of high-throughput genetic analysis have led to the identification of genes responsible for familial renal epithelial tumors of differing histologies and cytogenetic features. Some of these genes (VHL) are known to have an important role in sporadic renal neoplasia. This article describes the various epithelial renal tumors most commonly encountered by the urologist, the molecular and cytogenetic distinctions between them, and the hereditary syndromes that predispose to these tumors. Consideration of these syndromes is important for proper treatment when one encounters patients with multiple renal tumors, tumors at an early age of onset, or patients with a positive family history of renal cell carcinoma.

[Molecular diagnostics of renal diseases with underlying genetic predisposition]

The genetic basis for dysplasia and tumors of the kidney has increasingly become the subject of cytogenetic and molecular genetic investigations over the last decade. For that reason, it is now possible to define the risk of disease recurrence more precisely in families with kidney diseases caused by genetic alterations. The relevant genes and the mutations have been identified for most of these diseases and genetic diagnostics are possible. However, it is necessary to evaluate in each individual case whether genetic diagnostics are reasonable. This will be discussed for polycystic renal diseases, agenesis and dysplasia of the kidney, and hereditary kidney tumors.

Genetic disorders and renal cell carcinoma

The study of hereditary RCC syndromes continues to provide significant insight into the pathways that are involved in renal cell tumorigenesis. The clinician should maintain a high level of suspicion for genetic disorders when patients present with early-onset or mult-focal RCC. Recognition of familial syndromes will facilitate the institution of parenchymal sparing measures, as well as appropriate screening and intervention for associated nonrenal manifestations.

Update on oncocytoma

Oncocytoma is the most common benign solid renal tumor, comprising roughly 5% of resected renal masses. Typically discovered incidentally, oncocytoma is generally asymptomatic and very rarely metastasizes; however, multifocal disease and coexistence with renal cell carcinoma can occur. No currently used imaging techniques can reliably distinguish between oncocytoma and malignant lesions; therefore, patients must undergo resection, or in certain circumstances, biopsy, to definitively establish diagnosis. Careful attention to pathologic features and the adjunctive use of immunostains can aid in discriminating oncocytoma from other renal tumors characterized by granular, eosinophilic cytoplasm, especially chromophobe renal cell carcinoma. Nephron-sparing and laparoscopic surgical approaches can be used to treat appropriately selected patients.