Comprehensive characterization of Alu-mediated breakpoints in germline VHL gene deletions and rearrangements in patients from 71 VHL families.

Von Hippel-Lindau (VHL) is a hereditary multisystem disorder caused by germline alterations in the VHL gene. VHL patients are at risk for benign as well as malignant lesions in multiple organs including kidney, adrenal, pancreas, the central nervous system, retina, endolymphatic sac of the ear, epididymis, and broad ligament. An estimated 30%-35% of all families with VHL inherit a germline deletion of one, two, or all three exons. In this study, we have extensively characterized germline deletions identified in patients from 71 VHL families managed at the National Cancer Institute, including 59 partial (PD) and 12 complete VHL deletions (CD). Deletions that ranged in size from 1.09 to 355 kb. Fifty-eight deletions (55 PD and 3 CD) have been mapped to the exact breakpoints. Ninety-five percent (55 of 58) of mapped deletions involve Alu repeats at both breakpoints. Several novel classes of deletions were identified in this cohort, including two cases that have complex rearrangements involving both deletion and inversion, two cases with inserted extra Alu-like sequences, six cases that involve breakpoints in Alu repeats situated in opposite orientations, and a "hotspot" PD of Exon 3 observed in 12 families that involves the same pair of Alu repeats.

H255Y and K508R missense mutations in tumour suppressor folliculin (FLCN) promote kidney cell proliferation.

Germline H255Y and K508R missense mutations in the folliculin (FLCN) gene have been identified in patients with bilateral multifocal (BMF) kidney tumours and clinical manifestations of Birt-Hogg-Dubé (BHD) syndrome, or with BMF kidney tumours as the only manifestation; however, their impact on FLCN function remains to be determined. In order to determine if FLCN H255Y and K508R missense mutations promote aberrant kidney cell proliferation leading to pathogenicity, we generated mouse models expressing these mutants using BAC recombineering technology and investigated their ability to rescue the multi-cystic phenotype of Flcn-deficient mouse kidneys. Flcn H255Y mutant transgene expression in kidney-targeted Flcn knockout mice did not rescue the multi-cystic kidney phenotype. However, expression of the Flcn K508R mutant transgene partially, but not completely, abrogated the phenotype. Notably, expression of the Flcn K508R mutant transgene in heterozygous Flcn knockout mice resulted in development of multi-cystic kidneys and cardiac hypertrophy in some mice. These results demonstrate that both FLCN H255Y and K508R missense mutations promote aberrant kidney cell proliferation, but to different degrees. Based on the phenotypes of our preclinical models, the FLCN H255Y mutant protein has lost it tumour suppressive function leading to the clinical manifestations of BHD, whereas the FLCN K508R mutant protein may have a dominant negative effect on the function of wild-type FLCN in regulating kidney cell proliferation and, therefore, act as an oncoprotein. These findings may provide mechanistic insight into the role of FLCN in regulating kidney cell proliferation and facilitate the development of novel therapeutics for FLCN-deficient kidney cancer.

Somatic alterations contributing to metastasis of a castration-resistant prostate cancer.

Metastatic castration-resistant prostate cancer (mCRPC) is a lethal disease, and molecular markers that differentiate indolent from aggressive subtypes are needed. We sequenced the exomes of five metastatic tumors and healthy kidney tissue from an index case with mCRPC to identify lesions associated with disease progression and metastasis. An Ashkenazi Jewish (AJ) germline founder mutation, del185AG in BRCA1, was observed and AJ ancestry was confirmed. Sixty-two somatic variants altered proteins in tumors, including cancer-associated genes, TMPRSS2-ERG, PBRM1, and TET2. The majority (n = 53) of somatic variants were present in all metastases and only a subset (n = 31) was observed in the primary tumor. Integrating tumor next-generation sequencing and DNA copy number showed somatic loss of BRCA1 and TMPRSS2-ERG. We sequenced 19 genes with deleterious mutations in the index case in additional mCRPC samples and detected a frameshift, two somatic missense alterations, tumor loss of heterozygosity, and combinations of germline missense SNPs in TET2. In summary, genetic analysis of metastases from an index case permitted us to infer a chronology for the clonal spread of disease based on sequential accrual of somatic lesions. The role of TET2 in mCRPC deserves additional analysis and may define a subset of metastatic disease.

HIF overexpression correlates with biallelic loss of fumarate hydratase in renal cancer: novel role of fumarate in regulation of HIF stability.

Individuals with hemizygous germline fumarate hydratase (FH) mutations are predisposed to renal cancer. These tumors predominantly exhibit functional inactivation of the remaining wild-type allele, implicating FH inactivation as a tumor-promoting event. Hypoxia-inducible factors are expressed in many cancers and are increased in clear cell renal carcinomas. Under normoxia, the HIFs are labile due to VHL-dependent proteasomal degradation, but stabilization occurs under hypoxia due to inactivation of HIF prolyl hydroxylase (HPH), which prevents HIF hydroxylation and VHL recognition. We demonstrate that FH inhibition, together with elevated intracellular fumarate, coincides with HIF upregulation. Further, we show that fumarate acts as a competitive inhibitor of HPH. These data delineate a novel fumarate-dependent pathway for regulating HPH activity and HIF protein levels.

PRDM10 RCC: A Birt-Hogg-Dubé-like Syndrome Associated With Lipoma and Highly Penetrant, Aggressive Renal Tumors Morphologically Resembling Type 2 Papillary Renal Cell Carcinoma.

OBJECTIVE: To characterize the clinical manifestations and genetic basis of a familial cancer syndrome in patients with lipomas and Birt-Hogg-Dubé-like clinical manifestations including fibrofolliculomas and trichodiscomas and kidney cancer. METHODS: Genomic analysis of blood and renal tumor DNA was performed. Inheritance pattern, phenotypic manifestations, and clinical and surgical management were documented. Cutaneous, subcutaneous, and renal tumor pathologic features were characterized. RESULTS: Affected individuals were found to be at risk for a highly penetrant and lethal form of bilateral, multifocal papillary renal cell carcinoma. Whole genome sequencing identified a germline pathogenic variant in PRDM10 (c.2029 T>C, p.Cys677Arg), which cosegregated with disease. PRDM10 loss of heterozygosity was identified in kidney tumors. PRDM10 was predicted to abrogate expression of FLCN, a transcriptional target of PRDM10, which was confirmed by tumor expression of GPNMB, a TFE3/TFEB target and downstream biomarker of FLCN loss. In addition, a sporadic papillary RCC from the TCGA cohort was identified with a somatic PRDM10 mutation. CONCLUSION: We identified a germline PRDM10 pathogenic variant in association with a highly penetrant, aggressive form of familial papillary RCC, lipomas, and fibrofolliculomas/trichodiscomas. PRDM10 loss of heterozygosity and elevated GPNMB expression in renal tumors indicate that PRDM10 alteration leads to reduced FLCN expression, driving TFE3-induced tumor formation. These findings suggest that individuals with Birt-Hogg-Dubé-like manifestations and subcutaneous lipomas, but without a germline pathogenic FLCN variant, should be screened for germline PRDM10 variants. Importantly, kidney tumors identified in patients with a pathogenic PRDM10 variant should be managed with surgical resection instead of active surveillance.

Succinate dehydrogenase kidney cancer: an aggressive example of the Warburg effect in cancer.

PURPOSE: Recently, a new renal cell cancer syndrome has been linked to germline mutation of multiple subunits (SDHB/C/D) of the Krebs cycle enzyme, succinate dehydrogenase. We report our experience with the diagnosis, evaluation and treatment of this novel form of hereditary kidney cancer. MATERIALS AND METHODS: Patients with suspected hereditary kidney cancer were enrolled on a National Cancer Institute institutional review board approved protocol to study inherited forms of kidney cancer. Individuals from families with germline SDHB, SDHC and SDHD mutations, and kidney cancer underwent comprehensive clinical and genetic evaluation. RESULTS: A total of 14 patients from 12 SDHB mutation families were evaluated. Patients presented with renal cell cancer at an early age (33 years, range 15 to 62), metastatic kidney cancer developed in 4 and some families had no manifestation other than kidney tumors. An additional family with 6 individuals found to have clear cell renal cell cancer that presented at a young average age (47 years, range 40 to 53) was identified with a germline SDHC mutation (R133X) Metastatic disease developed in 2 of these family members. A patient with a history of carotid body paragangliomas and an aggressive form of kidney cancer was evaluated from a family with a germline SDHD mutation. CONCLUSIONS: SDH mutation associated renal cell carcinoma can be an aggressive type of kidney cancer, especially in younger individuals. Although detection and management of early tumors is most often associated with a good outcome, based on our initial experience with these patients and our long-term experience with hereditary leiomyomatosis and renal cell carcinoma, we recommend careful surveillance of patients at risk for SDH mutation associated renal cell carcinoma and wide surgical excision of renal tumors.

Mutations in a novel gene lead to kidney tumors, lung wall defects, and benign tumors of the hair follicle in patients with the Birt-Hogg-Dubé syndrome.

Birt-Hogg-Dubé (BHD) syndrome is a rare inherited genodermatosis characterized by hair follicle hamartomas, kidney tumors, and spontaneous pneumothorax. Recombination mapping in BHD families delineated the susceptibility locus to 700 kb on chromosome 17p11.2. Protein-truncating mutations were identified in a novel candidate gene in a panel of BHD families, with a 44% frequency of insertion/deletion mutations within a hypermutable C(8) tract. Tissue expression of the 3.8 kb transcript was widespread, including kidney, lung, and skin. The full-length BHD sequence predicted a novel protein, folliculin, that was highly conserved across species. Discovery of disease-causing mutations in BHD, a novel kidney cancer gene associated with renal oncocytoma or chromophobe renal cancer, will contribute to understanding the role of folliculin in pathways common to skin, lung, and kidney development.

Improved identification of von Hippel-Lindau gene alterations in clear cell renal tumors.

PURPOSE: To provide a comprehensive, thorough analysis of somatic mutation and promoter hypermethylation of the von Hippel-Lindau (VHL) gene in the cancer genome, unique to clear cell renal cancer (ccRCC). Identify relationships between the prevalence of VHL gene alterations and alteration subtypes with patient and tumor characteristics. EXPERIMENTAL DESIGN: As part of a large kidney cancer case-control study conducted in Central Europe, we analyzed VHL mutations and promoter methylation in 205 well-characterized, histologically confirmed patient tumor biopsies using a combination of sensitive, high-throughput methods (endonuclease scanning and Sanger sequencing) and analysis of 11 CpG sites in the VHL promoter. RESULTS: We identified mutations in 82.4% of cases, the highest VHL gene mutation prevalence reported to date. Analysis of 11 VHL promoter CpG sites revealed that 8.3% of tumors were hypermethylated and all were mutation negative. In total, 91% of ccRCCs exhibited alteration of the gene through genetic or epigenetic mechanisms. Analysis of patient and tumor characteristics revealed that certain mutation subtypes were significantly associated with Fuhrman nuclear grade, metastasis, node positivity, and self-reported family history of RCC. CONCLUSION: Detection of VHL gene alterations using these accurate, sensitive, and practical methods provides evidence that the vast majority of histologically confirmed ccRCC tumors possess genetic or epigenetic alteration of the VHL gene and support the hypothesis that VHL alteration is an early event in ccRCC carcinogenesis. These findings also indicate that VHL molecular subtypes can provide a sensitive marker of tumor heterogeneity among histologically similar ccRCC cases for etiologic, prognostic, and translational studies.

Hepatic vascular tumors, angiectasis in multiple organs, and impaired spermatogenesis in mice with conditional inactivation of the VHL gene.

von Hippel-Lindau (VHL) disease is a multisystem inherited cancer syndrome characterized by the development of highly vascular tumors including hemangioblastomas of the retina and central nervous system, pheochromocytomas, and clear cell renal carcinoma, which result from somatic inactivation of the wild-type VHL allele in cells harboring a germ-line VHL mutation. Homozygous inactivation of the VHL gene in mice resulted in embryonic lethality. To produce a mouse model that closely mimics human VHL disease and avoids embryonic lethality, we used Cre/lox site-specific recombination technology. We generated mice carrying conditional VHL alleles and a cre transgene under the control of the human beta-actin promoter, which directs cre expression in a mosaic pattern in multiple organs. VHL(f/d)/Cre mice developed multiple, hepatic hemangiomas that led to premature death, as well as angiectasis and angiogenesis in multiple organs. Interestingly, testes of male VHL(f/d)/Cre mice were unusually small with severely reduced sperm count resulting in infertility. Loss of pVHL function in this VHL conditional knockout mouse model results in an extensive abnormal vascular phenotype in multiple mouse organs, which will provide a useful animal model for testing potential antiangiogenic therapies for VHL disease treatment. Importantly, the phenotypic defects in sperm development observed in these mice support a novel role for VHL in spermatogenesis. This VHL conditional knockout mouse model will provide an in vivo system for studying the functional requirement of the VHL gene in reproductive biology.

Genetic basis of cancer of the kidney: disease-specific approaches to therapy.

Studies during the past two decades have shown that kidney cancer is not a single disease; it is made up of a number of different types of cancer that occur in this organ. Clear cell renal carcinoma is characterized by mutation of the VHL gene. The VHL gene product forms a heterotrimeric complex with elongin C, elongin B, and Cul-2 to target hypoxia-inducible factors 1 and 2alpha for ubiquitin-mediated degradation. VHL-/- clear cell renal carcinoma overexpresses epidermal growth factor receptor and transforming growth factor alpha. Both hypoxia-inducible factor 1alpha and the epidermal growth factor receptor are potential therapeutic targets in clear cell renal carcinoma. Studies of the hereditary form of renal cell carcinoma (RCC) associated with hereditary papillary renal carcinoma (HPRC) determined that the c-Met proto-oncogene on chromosome 7 is the gene for HPRC and for a number of sporadic papillary RCCs. The HPRC c-Met mutations are activating mutations in the tyrosine kinase domain of the gene. The gene for a new form of hereditary RCC (Birt Hogg Dubé syndrome) associated with cutaneous tumors, lung cysts, and colon polyps or cancer has recently been identified. Studies are currently under way to determine what type of gene BHD is and how damage to this gene leads to kidney cancer. Individuals affected with hereditary leiomyomatosis renal cell carcinoma are at risk for the development of cutaneous leiomyomas, uterine leiomyomas (fibroids), and type 2 papillary RCC. The HLRC gene has been found to be the Krebs cycle enzyme, fumarate hydratase. Studies are under way to understand the downstream pathway of this cancer gene.

Solid renal tumor severity in von Hippel Lindau disease is related to germline deletion length and location.

von Hippel Lindau disease (VHL) is an autosomal dominant familial cancer syndrome linked to alteration of the VHL tumor suppressor gene. Affected patients are predisposed to develop pheochromocytomas and cystic and solid tumors of the kidney, CNS, pancreas, retina, and epididymis. However, organ involvement varies considerably among families and has been shown to correlate with the underlying germline alteration. Clinically, we observed a paradoxically lower prevalence of renal cell carcinoma (RCC) in patients with complete germline deletion of VHL. To determine if a relationship existed between the type of VHL deletion and disease, we retrospectively evaluated 123 patients from 55 families with large germline VHL deletions, including 42 intragenic partial deletions and 13 complete VHL deletions, by history and radiographic imaging. Each individual and family was scored for cystic or solid involvement of CNS, pancreas, and kidney, and for pheochromocytoma. Germline deletions were mapped using a combination of fluorescent in situ hybridization (FISH) and quantitative Southern and Southern blot analysis. An age-adjusted comparison demonstrated a higher prevalence of RCC in patients with partial germline VHL deletions relative to complete deletions (48.9 vs. 22.6%, p=0.007). This striking phenotypic dichotomy was not seen for cystic renal lesions or for CNS (p=0.22), pancreas (p=0.72), or pheochromocytoma (p=0.34). Deletion mapping revealed that development of RCC had an even greater correlation with retention of HSPC300 (C3orf10), located within the 30-kb region of chromosome 3p, immediately telomeric to VHL (52.3 vs. 18.9%, p <0.001), suggesting the presence of a neighboring gene or genes critical to the development and maintenance of RCC. Careful correlation of genotypic data with objective phenotypic measures will provide further insight into the mechanisms of tumor formation.

Risk of renal and colonic neoplasms and spontaneous pneumothorax in the Birt-Hogg-Dubé syndrome.

The Birt-Hogg-Dubé syndrome, a genodermatosis characterized by benign tumors of the hair follicle, has been associated with renal and colonic neoplasms and spontaneous pneumothorax, but the risk of developing these disorders is unknown. We identified risk factors for renal tumors and spontaneous pneumothorax in 98 patients affected with the Birt-Hogg-Dubé syndrome, in 13 Birt-Hogg-Dubé haplotype carriers, and in 112 unaffected family members. Development of renal tumors was strongly associated with the Birt-Hogg-Dubé syndrome and age. The odds ratio for renal tumor in BHD-affected family members adjusted for age was 6.9 (95% confidence interval, 1.5-31.6) and approximately 9.0 for the other risk factors considered. Chromophobe renal carcinoma, an uncommon type of renal cancer, was the predominant type of renal cancer found. Spontaneous pneumothorax was also strongly associated with the Birt-Hogg-Dubé syndrome and age. The odds ratio for pneumothorax in BHD-affected individuals, adjusted for age, was 50.3 (95% confidence interval, 6.4-392), and about 32 times higher adjusting for the other risk variables. Colon cancer and colon polyps were not related to the Birt-Hogg-Dubé syndrome. The Birt-Hogg-Dubé syndrome confers an increased risk for the development of renal tumors and spontaneous pneumothorax. We found no increase in risk for the development of colon polyps or colon carcinomas.

Renal tumors in the Birt-Hogg-Dubé syndrome.

Birt-Hogg-Dubé (BHD) syndrome is an autosomal dominant genodermatosis characterized by the development of small dome-shaped papules on the face, neck, and upper trunk (fibrofolliculomas). In addition to these benign hair follicle tumors, BHD confers an increased risk of renal neoplasia and spontaneous pneumothorax. To date, there has been no systematic pathologic analysis of the renal tumors associated with this syndrome. We reviewed 130 solid renal tumors resected from 30 patients with BHD in 19 different families. Preoperative computed tomography scans demonstrated a mean of 5.3 tumors per patient (range 1-28 tumors), the largest tumors averaging 5.7 cm in diameter (+/- 3.4 cm, range 1.2-15 cm). Multiple and bilateral tumors were noted at an early age (mean 50.7 years). The resected tumors consisted predominantly of chromophobe renal cell carcinomas (44 of 130, 34%) or of hybrid oncocytic neoplasms that had areas reminiscent of chromophobe renal cell carcinoma and oncocytoma (65 of 130, 50%). Twelve clear cell (conventional) renal carcinomas (12 of 130, 9%) were diagnosed in nine patients. These tumors were on average larger (4.7 +/- 4.2 cm) than the chromophobe (3.0 +/- 2.5 cm) and hybrid tumors (2.2 +/- 2.4 cm). Microscopic oncocytosis was found in the renal parenchyma of most patients, including the parenchyma of five patients with evidence of clear cell renal cell carcinoma. Our findings suggest that microscopic oncocytic lesions may be precursors of hybrid oncocytic tumors, chromophobe renal cell carcinomas, and perhaps clear cell renal cell carcinomas in patients with BHD syndrome. Recognition by the pathologist of the unusual renal tumors associated with BHD may assist in the clinical diagnosis of the syndrome.

Effects of different fixatives on beta-galactosidase activity.

beta-Galactosidase (beta-Gal) staining is widely used to demonstrate specific gene expression during evaluation of gene targets in vivo. This technique is extremely sensitive to fixation. Optimal fixation conditions are necessary to obtain the maximal beta-Gal activity. In this experiment, Carnoy's and three different aldehyde fixatives were used at different temperatures and over different time points. Kidneys from LacZ-stop-human alkaline phosphatase (ZA/P) double reporter mice were used to generate positive material for the experiment. The results show that glutaraldehyde combinative solution (LacZ) produced the most consistent and reliable results. Paraformaldehyde and formaldehyde were effective as fixatives only at 4C for a period of less than 4 hr, and Carnoy's solution destroyed beta-Gal activity.

Kidney-targeted Birt-Hogg-Dube gene inactivation in a mouse model: Erk1/2 and Akt-mTOR activation, cell hyperproliferation, and polycystic kidneys.

BACKGROUND: Patients with Birt-Hogg-Dubé (BHD) syndrome harbor germline mutations in the BHD tumor suppressor gene that are associated with an increased risk for kidney cancer. BHD encodes folliculin, a protein that may interact with the energy- and nutrient-sensing 5'-AMP-activated protein kinase-mammalian target of rapamycin (AMPK-mTOR) signaling pathways. METHODS: We used recombineering methods to generate mice with a conditional BHD allele and introduced the cadherin 16 (KSP)-Cre transgene to target BHD inactivation to the kidney. Kidney cell proliferation was measured by BrdU incorporation and phospho-histone H3 staining. Kidney weight data were analyzed with Wilcoxon's rank-sum, Student's t, and Welch's t tests. Hematoxylin and eosin staining and immunoblot analysis and immunohistochemistry of cell cycle and signaling proteins were performed on mouse kidney cells and tissues. BHD knockout mice and kidney cells isolated from BHD knockout and control mice were treated with the mTOR inhibitor rapamycin. Mouse survival was evaluated by Kaplan-Meier analyses. All statistical tests were two-sided. RESULTS: BHD knockout mice developed enlarged polycystic kidneys and died from renal failure by 3 weeks of age. Targeted BHD knockout led to the activation of Raf-extracellular signal-regulated protein kinase (Erk)1/2 and Akt-mTOR pathways in the kidneys and increased expression of cell cycle proteins and cell proliferation. Rapamycin-treated BHD knockout mice had smaller kidneys than buffer-treated BHD knockout mice had (n = 4-6 mice per group, relative kidney/body weight ratios, mean = 4.64% vs 12.2%, difference = 7.6%, 95% confidence interval = 5.2% to 10.0%; P < .001) and longer median survival time (n = 4-5 mice per group, 41.5 vs 23 days; P = .0065 ). CONCLUSIONS: Homozygous loss of BHD may initiate renal tumorigenesis in the mouse. The conditional BHD knockout mouse may be a useful research model for dissecting multistep kidney carcinogenesis, and rapamycin may be considered as a potential treatment for Birt-Hogg-Dubé syndrome.

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.

Hereditary leiomyomatosis and renal cell cancer: a syndrome associated with an aggressive form of inherited renal cancer.

PURPOSE: Hereditary leiomyomatosis and renal cell cancer is a recently described hereditary cancer syndrome in which affected individuals are at risk for cutaneous and uterine leiomyomas, and kidney cancer. Our initial experience revealed the aggressive behavior of these renal tumors, often with early metastasis, despite small primary tumor size. We report the clinical characteristics and urological treatment of patients with hereditary leiomyomatosis and renal cell cancer associated renal tumors. MATERIALS AND METHODS: A total of 19 patients with hereditary leiomyomatosis and renal cell cancer associated renal tumors were evaluated. The 11 women and 8 men had a median age at diagnosis of 39 years (range 22 to 67), and a median clinical and radiological followup of 34 months (range 6 to 141). Hereditary leiomyomatosis and renal cell cancer manifestations in patients with renal tumors included cutaneous leiomyomas in 11 of 17 evaluable patients (65%) and uterine leiomyomas in 7 of 7 evaluable females (100%). RESULTS: Median pathological tumor size was 7.8 cm (range 1.5 to 20). Histological subtypes were consistent with hereditary leiomyomatosis and renal cell cancer renal carcinoma. Four of 7 patients with 2.0 to 6.7 cm T1 tumors had spread to regional lymph nodes or metastases at nephrectomy. Overall 9 of 19 patients (47%) presented with nodal or distant metastases. CONCLUSIONS: Renal tumors in patients with hereditary leiomyomatosis and renal cell cancer syndrome are significantly more aggressive than those in patients with other hereditary renal tumor syndromes. In contrast to other familial renal cancer syndromes, the observation of 3 cm or less renal tumors associated with hereditary leiomyomatosis and renal cell cancer is not recommended. Careful followup of affected and at risk individuals in families is necessary.

Lung cysts, spontaneous pneumothorax, and genetic associations in 89 families with Birt-Hogg-Dubé syndrome.

RATIONALE: Birt-Hogg-Dubé syndrome (BHDS) is an autosomal, dominantly inherited genodermatosis that predisposes to fibrofolliculomas, kidney neoplasms, lung cysts, and spontaneous pneumothorax. OBJECTIVES: We evaluated 198 patients from 89 families with BHDS to characterize the risk factors for pneumothorax and genotype-pulmonary associations. METHODS: Helical computed tomography scans of the chest were used to screen for pulmonary abnormalities. BHD mutation data were used for genotype-pulmonary associations. We examined the relationship of pneumothorax with categorical parameters (sex, smoking history, and lung cysts) and continuous parameters (number of cysts, lung cyst volume, and largest cyst diameter and volume). Logistic regression analyses were used to identify the risk factors associated with pneumothorax. MEASUREMENTS AND MAIN RESULTS: Twenty-four percent (48/198) of patients with BHDS had a history of pneumothorax. The presence of lung cysts was significantly associated with pneumothorax (p = 0.006). Total lung cyst volume, largest cyst diameter and volume, and every parameter related to the number of lung cysts were significantly associated (p < 0.0001) with pneumothorax. A logistic regression analysis showed that only the total number of cysts in the right parenchymal lower lobe and the total number of cysts located on the pleural surface in the right middle lobe were needed to classify a patient as to whether or not he or she was likely to have a pneumothorax. Exon location of the BHD mutation was associated with the numbers of cysts (p = 0.0002). CONCLUSIONS: This study indicates that patients with BHDS have a significant association between lung cysts and spontaneous pneumothorax.