McClellan M. Walther

von Hippel-Lindau disease

von Hippel-Lindau disease is a heritable multisystem cancer syndrome that is associated with a germline mutation of the VHL tumour suppressor gene on the short arm of chromosome 3. This disorder is not rare (about one in 36000 livebirths) and is inherited as a highly penetrant autosomal dominant trait (ie, with a high individual risk of disease). Affected individuals are at risk of developing various benign and malignant tumours of the central nervous system, kidneys, adrenal glands, pancreas, and reproductive adnexal organs. Because of the complexities associated with management of the various types of tumours in this disease, treatment is multidisciplinary. We present an overview of the clinical aspects, management, and treatment options for von Hippel-Lindau disease.

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.

Recent advances in genetics, diagnosis, localization, and treatment of pheochromocytoma.

Dr. Karel Pacak (Pediatric and Reproductive Endocrinology Branch, National Institute of Child Health and Human Development [NICHD] and Clinical Neurocardiology Section, National Institute of Neurological Disorders and Stroke [NINDS], National Institutes of Health [NIH], Bethesda, Maryland): Pheochromocytomas are chromaffin cell tumors that, although rare, must be considered in patients with hypertension, autonomic disturbances, panic attacks, adrenal incidentalomas, or familial diseases featuring a predisposition to develop pheochromocytoma. Hypertension, whether sustained or paroxysmal, is the most common clinical sign, and headache, excessive truncal sweating, and palpitations are the most common symptoms (1). Pallor is also common, whereas flushing occurs less frequently. Some patients present with severe episodes of anxiety, nervousness, or panic. Patients with a familial predisposition or small incidentally discovered adrenal masses can be normotensive and asymptomatic. The low pretest prevalence of pheochromocytomaclose to 0.5% among those tested because of hypertension and suggestive symptoms (1) and as high as 4% in patients with adrenal incidentaloma (2)together with imperfect sensitivity and specificity of commonly used biochemical and imaging tests, can make diagnosis and localization of pheochromocytoma difficult. Effective methods for diagnosis and localization are important because seemingly mild stimuli can provoke the tumor to release large amounts of catecholamines, with severe or fatal consequences. Moreover, surgical removal can cure pheochromocytoma in up to 90% of cases, whereas if left untreated the tumor can prove fatal. Advances in genetic mutation analysis have greatly improved identification of patients with familial pheochromocytoma, allowing detection of tumors at an early stage, often before typical signs and symptoms occur. These advances provide new insights into the biology and natural history of the disease and highlight inadequacies of commonly used diagnostic tests. In turn, new developments have been made in the management of patients with familial pheochromocytoma and in surgical procedures for preserving normal adrenal cortical tissue in persons with bilateral adrenal tumors. In this paper, we summarize advances in the genetics, biochemical diagnosis, localization, and management of pheochromocytoma and also note key questions that remain unanswered. Molecular Genetic Abnormalities Associated with Pheochromocytoma Drs. W. Marston Linehan and McClellan M. Walther (Urologic Oncology Branch, National Cancer Institute [NCI], NIH, Bethesda, Maryland): Pheochromocytomas may be classified as sporadic or familial. Most pheochromocytomas are sporadic. Familial predisposition is seen mainly in patients with multiple endocrine neoplasia type II (MEN II), von HippelLindau disease, neurofibromatosis type 1, and familial carotid body tumors (Table 1). The exact molecular mechanisms by which the hereditary mutations predispose to tumor development remain unknown. Hereditary forms of pheochromocytoma can differ in rate of tumor growth, malignant potential, and catecholamine phenotype. Table 1. Hereditary Forms of Pheochromocytoma Cancer Genes Identification of a cancer gene can help us understand the origin of cancer, such as pheochromocytoma, and elucidate mechanisms of tumor formation and behavior. Moreover, identification of a disease gene provides a method for genetic diagnosis. Phenotypic manifestations of a hereditary cancer syndrome can vary markedly, and genetic tests can confirm the diagnosis when the clinical presentation is complex. Finally, understanding of cancer genes may provide targets for therapy. The two most studied types of cancer genes are tumor suppressor genes (Figure 1) and oncogenes (7). When mutated, a proto-oncogene becomes activated, resulting in an oncogene. This is referred to as a single hit; that is, the proto-oncogene undergoes a single activating mutation that turns it into an oncogene (8, 9). Familial predisposition to pheochromocytoma in patients with MEN II results from such a mechanism. In contrast, a tumor suppressor gene is a loss-of-function gene, in which inactivation of both copies of the gene causes unregulated cell growth and division. This loss of function can result from mutation of one allele of a tumor suppressor gene and deletion of the second copy (10). Examples of tumor suppressor genes are the retinoblastoma gene, the Wilms tumor gene, the tuberous sclerosis genes, and, in the case of pheochromocytoma, the von HippelLindau gene (11-19). Figure 1. The Knudson two-hit model. Pheochromocytoma in Multiple Endocrine Neoplasia Type II: RETGene Multiple endocrine neoplasia type IIA is characterized clinically by the familial association of medullary thyroid cancer, pheochromocytoma, and parathyroid hyperplasia. Mucosal ganglioneuromas are also found in some patients (MEN IIB). Pheochromocytoma in MEN II is associated with germline mutation of the proto-oncogene RET. This proto-oncogene becomes an oncogene when an activating mutation occurs (20-25). The activating mutation in the RETgene drives the abnormal cellular proliferation that leads to adrenal medullary hyperplasia and pheochromocytoma. Several RETgermline mutations are associated with the development of pheochromocytoma, with some variation dependent on the particular mutation (3-5, 26, 27) (Table 1). Pheochromocytoma in von HippelLindau Disease: the von HippelLindau Gene Patients with von HippelLindau disease have a germline mutation of the von HippelLindau gene (28). Affected persons can develop early-onset bilateral kidney tumors and cysts, pheochromocytomas, cerebellar and spinal hemangioblastomas, retinal angiomas, pancreatic cysts and tumors, epididymal cystadenomas, and tumors in the endolymphatic sac canal of the inner ear (29-31). von HippelLindau disease has marked phenotypic heterogeneity. While patients from some families present with central neural, eye, kidney, and pancreatic tumors, patients in other families present mainly with pheochromocytoma (30, 32, 33). Some reports have described families thought to have familial pheochromocytoma who proved to have von HippelLindau disease (32, 34-37). Missense mutations in the von HippelLindau gene are associated with the development of pheochromocytoma more than twice as often as are other types of mutations (74% vs. 32%) (6, 33). Molecular Genetic Diagnosis von HippelLindau disease and MEN II have a similar prevalence (approximately 1 in 30 000 to 1 in 45 500). Mutations predisposing to pheochromocytoma have greater penetrance in MEN II than in von HippelLindau disease (38, 39). Pheochromocytoma in von HippelLindau families has been reported as familial pheochromocytoma or MEN II (40, 41). Because different kindreds can present with different phenotypes, it can be difficult to distinguish between von HippelLindau disease and MEN II in some patients with familial pheochromocytoma. Patients with bilateral adrenal, recurrent, or multifocal pheochromocytoma should undergo clinical or genetic testing for mutations of the von HippelLindau or RETgenes. The availability of germline testing for both von HippelLindau (42) and RET (15, 20, 23, 40, 43) gene mutations (at OncorMed in Gaithersburg, Maryland, and at the University of Pennsylvania in Philadelphia) has improved the clinical management of patients with hereditary pheochromocytoma. When a patient presents with a family history in which the primary manifestation is pheochromocytoma, the von HippelLindau gene is a likely cause. Some von HippelLindau families present mainly with pheochromocytoma and occult or delayed manifestations in the central nervous system, eye, or other organs. It is less likely that a member of a MEN II family will present predominantly with pheochromocytoma because most of these patients have medullary thyroid carcinoma (44). A small number of families with familial pheochromocytoma have neither von HippelLindau nor RETgermline mutations, and the genetic basis for this is currently being studied. Biochemical Diagnosis of Pheochromocytoma Dr. Graeme Eisenhofer (Clinical Neurocardiology Section, NINDS, NIH, Bethesda, Maryland): Diagnosis of pheochromocytoma usually requires biochemical evidence of excessive catecholamine production by the tumor, usually achieved from measurements of catecholamines or catecholamine metabolites in urine or plasma. These biochemical approaches, however, have several limitations. Since catecholamines are normally produced by sympathetic nerves and by the adrenal medulla, high catecholamine levels are not specific to pheochromocytoma and may accompany other conditions or disease states. In addition, sometimes pheochromocytomas do not secrete enough catecholamines to produce positive test results or typical signs and symptoms. In addition, pheochromocytomas often secrete catecholamines episodically. Between episodes, levels of catecholamines may be normal. Thus, commonly used tests of plasma or urinary catecholamines and metabolites and other biochemical tests, such as measurements of plasma chromogranin A levels, do not always reliably exclude or confirm a tumor (45-55). A recently developed biochemical test, involving measurements of plasma levels of free metanephrines (o-methylated metabolites of catecholamines), circumvents many of the above problems and offers a more effective means to diagnose pheochromocytoma than other tests (46, 56). Sensitivity of Biochemical Tests Measurements of plasma levels of normetanephrine and metanephrine have higher sensitivity than other biochemical tests for diagnosis of both sporadic and familial pheochromocytoma (46, 56). In familial pheochromocytoma, periodic screening can lead to early-stage detection before symptoms and signs, when tumors are small and are not secreting large amounts of catecholamines (6). The difficulty of biochemical diagnosis of familial pheochromocytoma is illustrated

Improved detection of germline mutations in the von Hippel-Lindau disease tumor suppressor gene

von Hippel‐Lindau disease (VHL) is an inherited neoplastic disorder characterized by the development of tumors in the eyes, brain, spinal cord, inner ear, adrenal gland, pancreas, kidney, and epididymis. The VHL tumor suppressor gene was identified in 1993. Initial studies reported the detection of germline mutations in the VHL gene in 39–75% of VHL families. We used tests that detect different types of mutations to improve the frequency of detection of germline mutations in VHL families. The methods included quantitative Southern blotting to detect deletions of the entire VHL gene, Southern blotting to detect gene rearrangements, fluorescence in situ hybridization (FISH) to confirm deletions, and complete sequencing of the gene. Here we report that we have detected germline mutations in the VHL gene in 100% (93/93) of VHL families tested. In addition, we describe 13 novel intragenic VHL germline mutations. With the methodology described in this article, it is now possible to identify germline mutations in virtually all families with VHL. Hum Mutat 12:417–423, 1998.

Cyclophosphamide-induced cystitis and bladder cancer in patients with Wegener granulomatosis.

Wegener granulomatosis is a necrotizing granulomatous vasculitis that typically involves the upper and lower respiratory tract and the kidneys. Standard therapy for Wegener granulomatosis includes the daily administration of low-dose oral cyclophosphamide and corticosteroid therapy [1, 2]. This therapeutic regimen has dramatically improved the survival of patients with this otherwise fatal disease: More than 90% of patients treated with cyclophosphamide and corticosteroid therapy improve markedly, and 75% achieve complete remission of disease [1, 3]. However, extended follow-up of patients with Wegener granulomatosis indicates that relapse of disease is common, and repeated and prolonged courses of cyclophosphamide can be associated with serious long-term toxicities, including bone marrow suppression, infertility, hemorrhagic cystitis, and the development of cancer [3]. Hemorrhagic cystitis and bladder cancer are well-recognized complications of cyclophosphamide therapy for both malignant [4] and nonmalignant diseases [3, 5-7]. However, the relations among total cyclophosphamide dose, the development of cystitis, and the occurrence of bladder cancer have not been well defined. In this report, we describe the incidence, clinical manifestations, and natural history of cyclophosphamide-mediated urotoxicity in a cohort of patients with Wegener granulomatosis. We identify risk factors associated with the development of cyclophosphamide-induced bladder cancer and discuss recommendations for surveillance. Methods Patients From 1967 to 1993, 145 patients with Wegener granulomatosis were treated with cyclophosphamide at the Warren G. Magnuson Clinical Center of the National Institutes of Health (NIH). The clinical features of the underlying disease in all but 3 of these patients have been reported previously [3]; the clinical and demographic characteristics of these patients are summarized in Table 1. Individual patients were followed for 0.5 to 27 years (median, 8.5 years), for a total of 1333 patient-years. Table 1. Demographic and Clinical Characteristics of 145 Patients with Wegener Granulomatosis Who Were Treated with Cyclophosphamide* Treatment Protocol We used the standard cyclophosphamide treatment regimen, which has been described previously [1, 3]. Therapy consisted of 1) oral cyclophosphamide, 2 mg/kg of body weight per day and 2) prednisone, 1 mg/kg of body weight per day. If patients improved substantially after the first month of treatment, the prednisone dose was gradually tapered to an alternate-day regimen, and prednisone therapy was eventually discontinued. Cyclophosphamide therapy was continued for at least 1 year after patients achieved complete remission. The cyclophosphamide dose was then tapered by 25-mg decrements of therapy every 2 to 3 months until discontinuation of therapy or until disease recurrence required an increase in dose. The cyclophosphamide dose was adjusted as needed to keep the absolute neutrophil count higher than 1.0 106/L. If substantial toxicity required the permanent discontinuation of cyclophosphamide therapy and if signs of active vasculitis were present, azathioprine, chlorambucil, or (after 1990) low-dose weekly methotrexate therapy was allowed. Eight patients with fulminant disease initially received intravenous cyclophosphamide at daily doses of 3 to 5 mg/kg. When their disease stabilized, these patients were switched to the standard oral cyclophosphamide regimen. Fourteen patients received monthly pulses of intravenous cyclophosphamide, 1 g/m2 body surface area; 13 of these 14 patients also received one or more courses of the standard oral cyclophosphamide regimen. Thus, 144 of the 145 patients received oral cyclophosphamide therapy for some period of time. Patients were evaluated at the NIH every 1 to 3 months. Those who achieved remission of disease and maintained it for 1 year were subsequently seen every 6 months. For each patient, urinalysis was done at every visit, and a cytologic examination of urine was done every 6 to 12 months. All patients received cyclophosphamide as part of clinical research protocols approved by the National Institute of Allergy and Infectious Diseases (NI-AID) Institutional Review Board, the NIAID Clinical Director, and the director of the NIH Clinical Center. All patients gave written informed consent. Urine Cytology Cytologic examination of urine was done at each evaluation. Sediments obtained from voided urine specimens were fixed in Saccomanno solution (Lerner Laboratories, Pittsburgh, Pennsylvania), immobilized on membrane filters (Millipore, Chicago, Illinois) or by cytospin, placed in 95% ethanol, and stained with Papanicolaou stain. Urine samples obtained as much as 6 months before each cystoscopic examination were reviewed retrospectively and were correlated with subsequent bladder biopsy specimens. Cellular cytologic features were placed in the following categories according to the following criteria [8-10]: 1. Negative: no important epithelial abnormalities. 2. Atypia: some nuclear abnormalities in epithelial cells, but the changes could not be definitely placed in categories 3, 4, or 5. 3. Therapeutic or viral: cytologic changes consistent with polyomavirus infection or cyclophosphamide toxicity. In the absence of diagnostic inclusions, the two types of changes are indistinguishable, and we therefore grouped them together. The nuclear enlargement and hyperchromasia associated with polyomavirus or chemotherapeutic effect should be distinguished from high-grade dysplasia or carcinoma. 4. Dysplasia or possible low-grade transitional-cell carcinoma: a few cells in a voided urine sample, either singly or in clusters, that have slightly enlarged, irregular nuclei with increased granularity in chromatin distribution and small or absent nucleoli. 5. Transitional-cell carcinoma: high-grade lesions meeting unequivocal criteria of malignancy. Definition of Terms Nonglomerular hematuria was defined as microscopic or gross hematuria not associated with the presence of erythrocyte casts or declining renal function. Glomerulonephritis causing hematuria associated with erythrocyte casts (glomerular hematuria) occurred at least once in 116 of the 145 patients (Table 1). If hematuria persisted after the treatment of glomerulonephritis and the disappearance of erythrocyte casts, or if hematuria not associated with the presence of erythrocyte casts ever developed, patients were considered to have nonglomerular hematuria and had cystoscopy (see below). Cyclophosphamide-induced cystitis was defined as nonglomerular hematuria associated with characteristic cystoscopic bladder changes. These changes included patchy areas of neovascularity and telangiectasia manifested as an increased number of tortuous, thin-walled veins and small areas of hemorrhage in or under the bladder epithelium. The mucosa between the hypervascular areas may appear normal or pale with decreased vascularity. Cystoscopy Cystoscopy was done to evaluate nonglomerular hematuria (microscopic or gross) in patients receiving cyclophosphamide. Only the results of cystoscopies done at the NIH Clinical Center by members of the Urologic Oncology Section of the National Cancer Institute are included in this report. Most of these cystoscopies were done by two of the authors; all cystoscopy results were reviewed by these two authors. Random biopsies were done only if the results of cytologic examination of urine suggested malignancy. Patients having cystoscopy had intravenous pyelography or retrograde pyelography, or both, at least once to evaluate the upper urinary tract. Statistical Analysis The frequencies of clinical findings were compared by using the Fisher exact test for association with bladder cancer and nonglomerular hematuria; adjustments were made for multiple comparisons of microscopic and gross hematuria with bladder cancer using the modified Bonferroni method [11]. The effects of fixed covariates (sex, history of smoking, age at onset of Wegener granulomatosis disease, and duration of disease before first cyclophosphamide treatment) and time-varying covariates (microscopic hematuria, gross hematuria, total cyclophosphamide dose, and duration of cyclophosphamide therapy) on the development of bladder cancer were examined using Cox proportional-hazards regression analysis [12, 13]. Medians and other percentiles for variables dependent on follow-up time were estimated by using the Kaplan-Meier method [14]. The cumulative distributions determined by the Kaplan-Meier method were compared with the log-rank test. Risk estimates for the development of bladder cancer in patients with Wegener granulomatosis who were treated with cyclophosphamide were determined by comparing observed rates with the expected rates for the United States population, which were obtained from the Surveillance, Epidemiology, and End Results (SEER) Cancer Statistics Review, 1973-1991 [15]. Results Hematuria Seventy-three of 145 patients treated with cyclophosphamide (50%) developed nonglomerular hematuria; the median time to development for all patients was 37 months of receipt of cyclophosphamide (95% CI, 32 to 55 months), and the median dose before development was 124 g (CI, 82 to 149 g) (Table 2 and Figure 1). Forty-one patients (56%) presented with microscopic hematuria; 32 (44%) presented with gross hematuria. Twenty-eight patients had more than one recurrent episode of nonglomerular hematuria (microscopic or gross), sometimes years after cyclophosphamide therapy had been discontinued. Eighteen of the 73 patients developed hematuria after cyclophosphamide therapy was discontinued. Manifestations of active vasculitis necessitated that cyclophosphamide therapy be continued in 26 of the 55 patients who developed nonglomerular hematuria while receiving this therapy. Table 2. Clinical Characteristics of the 73 Patients Treated with Cyclophosphamide Who Developed Nonglomerular Hematuria Figure 1. Cumulative r

Mutations in the Fumarate Hydratase Gene Cause Hereditary Leiomyomatosis and Renal Cell Cancer in Families in North America

Hereditary leiomyomatosis and renal cell cancer (HLRCC) is an autosomal dominant disorder characterized by smooth-muscle tumors of the skin and uterus and/or renal cancer. Although the identification of germline mutations in the fumarate hydratase (FH) gene in European families supports it as the susceptibility gene for HLRCC, its role in families in North America has not been studied. We screened for germline mutations in FH in 35 families with cutaneous leiomyomas. Sequence analysis revealed mutations in FH in 31 families (89%). Twenty different mutations in FH were identified, of which 18 were novel. Of these 20 mutations, 2 were insertions, 5 were small deletions that caused frameshifts leading to premature truncation of the protein, and 13 were missense mutations. Eleven unrelated families shared a common mutation: R190H. Eighty-one individuals (47 women and 34 men) had cutaneous leiomyomas. Ninety-eight percent (46/47) of women with cutaneous leiomyomas also had uterine leiomyomas. Eighty-nine percent (41/46) of women with cutaneous and uterine leiomyomas had a total hysterectomy, 44% at age < or =30 years. We identified 13 individuals in 5 families with unilateral and solitary renal tumors. Seven individuals from four families had papillary type II renal cell carcinoma, and another individual from one of these families had collecting duct carcinoma of the kidney. The present study shows that mutations in FH are associated with HLRCC in North America. HLRCC is associated with clinically significant uterine fibroids and aggressive renal tumors. The present study also expands the histologic spectrum of renal tumors and FH mutations associated with HLRCC.

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.

Plasma Normetanephrine and Metanephrine for Detecting Pheochromocytoma in von Hippel–Lindau Disease and Multiple Endocrine Neoplasia Type 2

BACKGROUND The detection of pheochromocytomas in patients at risk for these tumors, such as patients with von Hippel-Lindau disease or multiple endocrine neoplasia type 2 (MEN-2), is hindered by the inadequate sensitivity of commonly available biochemical tests. In this study we evaluated measurements of plasma normetanephrine and metanephrine for detecting pheochromocytomas in patients with von Hippel-Lindau disease or MEN-2. METHODS We studied 26 patients with von Hippel-Lindau disease and 9 patients with MEN-2 who had histologically verified pheochromocytomas and 50 patients with von Hippel-Lindau disease or MEN-2 who had no radiologic evidence of pheochromocytoma. Von Hippel-Lindau disease and MEN-2 were diagnosed on the basis of germ-line mutations of the appropriate genes. The plasma concentrations of normetanephrine and metanephrine were compared with the plasma concentrations of catecholamines (norepinephrine and epinephrine) and urinary excretion of catecholamines, metanephrines, and vanillylmandelic acid. RESULTS The sensitivity of measurements of plasma normetanephrine and metanephrine for the detection of tumors was 97 percent, whereas the other biochemical tests had a sensitivity of only 47 to 74 percent. All patients with MEN-2 had high plasma concentrations of metanephrine, whereas the patients with von Hippel-Lindau disease had almost exclusively high plasma concentrations of only normetanephrine. One patient with von Hippel-Lindau disease had a normal plasma normetanephrine concentration; this patient had a very small adrenal tumor (<1 cm). The high sensitivity of measurements of plasma normetanephrine and metanephrine was accompanied by a high level of specificity (96 percent). CONCLUSIONS Measurements of plasma normetanephrine and metanephrine are useful in screening for pheochromocytomas in patients with a familial predisposition to these tumors.

Hereditary papillary renal cell carcinoma.

We describe a 3 generation family with members affected with papillary renal cell carcinoma, an uncommon histological type of renal cell carcinoma. Multiple tumors of varying size were present in both kidneys of affected family members. The disorder was not linked to polymorphic markers on chromosome 3p and there was no loss of heterozygosity at loci on 3p in renal tumors. The results suggest the presence of a renal cell carcinoma gene not located on 3p that predisposes to renal cell carcinoma with a distinct histological appearance. The inherited disorder in this family appears to be different from recognized hereditary cancer syndromes.

Multiple Neuroendocrine Tumors of the Pancreas in von Hippel-Lindau Disease Patients : Histopathological and Molecular Genetic Analysis

Although pancreatic neuroendocrine tumors (NETs) in von Hippel-Lindau (VHL) disease have been reported, their pathological features have not been characterized. In addition, it is unknown whether alterations of the VHL gene are responsible for pancreatic NET development. To evaluate NETs in VHL patients, we performed histopathological analysis of 30 pancreatic tumors in 14 patients. In addition, DNA from NETs and normal pancreatic tissue from 6 patients with documented germ-line VHL gene mutations was studied for allelic deletions of the second copy of the VHL gene by fluorescence in situ hybridization and polymerase chain reaction-based single-strand conformational polymorphism analysis. Morphologically, the tumors were characterized by solid, trabecular, and/or glandular architecture and prominent stromal collagen bands. Sixty percent of the tumors revealed at least focally clear-cell cytology. All tumors were positive for panendocrine immunohistochemistry markers (chromogranin A and/or synaptophysin); 35% of NETs demonstrated focal positivity for pancreatic polypeptide, somatostatin, insulin, and/or glucagon; and no immunostaining for pancreatic and gastrointestinal hormones was observed in 65% of tumors. Dense core neurosecretory granules were evident by electron microscopic examination, and the clear cells additionally revealed abundant intracytoplasmic lipid. All NETs that were subjected to genetic analysis showed allelic loss of the second copy of the VHL gene. We conclude that multiple, nonfunctional pancreatic NETs occur in VHL patients. Stromal collagen bands and clear-cell morphology are important histological features of VHL-associated NETs. The presence of allelic deletions of the VHL gene in pancreatic NETs provides direct molecular evidence for a role of the gene in their tumorigenesis and establishes NET as an independent tumor type of VHL disease.