Sven Gläsker

The impact of molecular genetic analysis of the VHL gene in patients with haemangioblastomas of the central nervous system

OBJECTIVES Haemangioblastoma of the CNS occurs as a sporadic entity and as a manifestation of the autosomal dominant von Hippel-Lindau disease with the major additional components retinal angioma, renal cancer, and pheochromocytoma. Genetic testing for germline mutations predisposing to von Hippel-Lindau disease has been available since identification of the VHL tumour suppressor gene. The impact of this testing was evaluated in patients with haemangioblastomas seen in this centre. METHODS A register and database of patients with symptomatic haemangioblastomas for the last 15 years was evaluated. The VHL gene was analysed by the SSCP method for all exons and Southern blotting for mutations and deletions of the gene. RESULTS 141 patients with haemangioblastoma of the CNS were registered. In 81 patients (57%) there was a disease predisposing germline mutation including eight novel mutations. Population related calculation of patients from the administrative district of Freiburg disclosedVHL germline mutations in 22% of the patients with haemangioblastoma. Analysis of mutation carriers for clinical information suggestive of the syndrome showed (1) a positive family history of a brain tumour in 50%, (2) a history for the patient of extracranial manifestations in 36% (retinal angioma 30%, pheochromocytoma 6%), and (3) 19% presenting with multiple brain tumours when first admitted. By genetic testing of haemangioblastoma patients without any indications of von Hippel-Lindau disease mutation carriers were identified in 14%. Sensitivity of VHL germline testing was 86%. CONCLUSIONS DNA analysis for VHL germline mutations is clearly superior to clinical information in the diagnosis of von Hippel-Lindau disease. Although the percentage of von Hippel-Lindau disease associated haemangioblastoma decreases after the fourth decade of life and is infrequent in patients without other symptomatic lesions and a negative family history, it is recommended that every patient with CNS haemangioblastoma should be screened for von Hippel-Lindau disease germline mutations. This provides the key information and enables screening for extraneurological tumours of the patients and investigations of the patient′s family to ameliorate management of von Hippel-Lindau disease.

Treatment of intramedullary hemangioblastomas, with special attention to von Hippel-Lindau disease.

OBJECTIVEHemangioblastomas of the central nervous system are rare vascular tumors that can occur as sporadic lesions or as component tumors of autosomal dominant von Hippel-Lindau disease. With the availability of magnetic resonance imaging, asymptomatic tumors are detected more frequently, especially among patients with von Hippel-Lindau disease, and the questions of whether and when these lesions should be treated arise. To identify surgical outcomes and the timing of surgery for intramedullary hemangioblastomas, we retrospectively analyzed data for a series of 28 consecutive patients whom we surgically treated for intramedullary hemangioblastomas in the past 10 years. METHODSAll tumors were completely removed. Functional grades, according to the McCormick scale, were determined before and after surgery and in follow-up assessments. Several clinical characteristics were correlated with changes in functional grades in follow-up assessments, compared with preoperative grades. RESULTSFunctional grades in follow-up assessments improved for 28.6% of the patients and remained unchanged for 71.4%. No patient was in worse condition, compared with preoperative status. Peritumoral edema on preoperative magnetic resonance imaging scans was correlated with significantly higher surgical morbidity rates. Four asymptomatic patients were surgically treated because of tumor or pseudocyst progression on serial magnetic resonance imaging scans. All of those patients remained asymptomatic postoperatively. CONCLUSIONIntramedullary hemangioblastomas can be removed with low surgical morbidity rates and excellent long-term prognoses. The timing of surgery for patients with von Hippel-Lindau disease and multiple lesions remains a matter of debate. On the basis of our data, we established the strategy of operating also on asymptomatic lesions that exhibit radiological progression, before significant neurological deficits occur, which are often not reversible.

Risk of hemorrhage in hemangioblastomas of the central nervous system.

OBJECTIVE:Hemangioblastomas are benign vascular tumors of the central nervous system. Several cases of spontaneous hemorrhage within these tumors have been reported. However, the risk of hemorrhage in these tumors remains unknown. METHODS:To clarify the incidence of hemorrhage in hemangioblastomas, we reviewed our large clinical database of 277 patients with central nervous system hemangioblastomas for the incidence of spontaneous or perioperative hemorrhage. Clinical characteristics such as tumor size, tumor location, von Hippel-Lindau disease status, and clinical symptoms before hemorrhage were correlated with hemorrhage risk. Furthermore, we reviewed the literature for cases of spontaneous hemorrhage from hemangioblastoma. RESULTS:Among all patients in our series, we observed seven cases of spontaneous hemorrhage from a hemangioblastoma within the summarized follow-up time. Thus, we calculate a spontaneous hemorrhage probability of 0.0024 per person per year. The average diameter of tumors that bled was 3 cm in our series and 2.3 cm in the literature review, whereas the average diameter of hemangioblastomas in major series ranges from 0.8 to 1.1 cm. Furthermore, we have observed severe postoperative hemorrhage in two extraordinarily large solid hemangioblastomas (4 and 5 cm). CONCLUSION:The overall incidence of hemorrhage in patients with hemangioblastoma is low. An important indicator for the probability of hemorrhage is tumor size, as spontaneous or postoperative hemorrhage occurred exclusively in extraordinarily large tumors. Hemangioblastomas smaller than 1.5 cm (the vast majority of these tumors) harbor virtually no risk of spontaneous hemorrhage.

Head and neck paragangliomas: clinical and molecular genetic classification

Head and neck paragangliomas are tumors arising from specialized neural crest cells. Prominent locations are the carotid body along with the vagal, jugular, and tympanic glomus. Head and neck paragangliomas are slowly growing tumors, with some carotid body tumors being reported to exist for many years as a painless lateral mass on the neck. Symptoms depend on the specific locations. In contrast to paraganglial tumors of the adrenals, abdomen and thorax, head and neck paragangliomas seldom release catecholamines and are hence rarely vasoactive. Petrous bone, jugular, and tympanic head and neck paragangliomas may cause hearing loss. The internationally accepted clinical classifications for carotid body tumors are based on the Shamblin Class I–III stages, which correspond to postoperative permanent side effects. For petrous-bone paragangliomas in the head and neck, the Fisch classification is used. Regarding the molecular genetics, head and neck paragangliomas have been associated with nine susceptibility genes: NF1, RET, VHL, SDHA, SDHB, SDHC, SDHD, SDHAF2 (SDH5), and TMEM127. Hereditary HNPs are mostly caused by mutations of the SDHD gene, but SDHB and SDHC mutations are not uncommon in such patients. Head and neck paragangliomas are rarely associated with mutations of VHL, RET, or NF1. The research on SDHA, SDHAF2 and TMEM127 is ongoing. Multiple head and neck paragangliomas are common in patients with SDHD mutations, while malignant head and neck paraganglioma is mostly seen in patients with SDHB mutations. The treatment of choice is surgical resection. Good postoperative results can be expected in carotid body tumors of Shamblin Class I and II, whereas operations on other carotid body tumors and other head and neck paragangliomas frequently result in deficits of the cranial nerves adjacent to the tumors. Slow growth and the tendency of hereditary head and neck paragangliomas to be multifocal may justify less aggressive treatment strategies.

Central nervous system manifestations in VHL: genetics, pathology and clinical phenotypic features

This review focuses on CNS hemangioblastomas in von Hippel–Lindau (VHL) disease. The pathogenesis of these lesions remains unclear to date; however, biallelic inactivation of the VHL tumor suppressor gene is thought to be an important step. These benign tumors occur frequently in patients with VHL disease and produce symptoms by mass effect either by the tumor itself or an accompanying cyst or edema. Furthermore, cases of spontaneous hemorrhage have been described. Genetic testing for VHL germline mutations is recommended in all patients with hemangioblastoma and yearly screening, including MRI of the brain and spine, is recommended for all VHL disease patients. Treatment of these tumors is mainly surgical. In general, surgery is indicated in symptomatic hemangioblastomas and eventually also in asymptomatic tumors that exhibit radiographic progression. However, since most VHL disease patients harbor multiple lesions, a careful individual decision must be made in each case. The tumors can usually be completely removed by dissection in the plane between tumor and CNS tissue and coagulating and cutting of the numerous feeding vessels with low power. As long as consequent yearly surveillance is performed and lesions are adequately treated in time, the prognosis of CNS hemangioblastomas in VHL disease is good. Preoperative neurological deficit, however, will not improve after surgery in most patients. Local tumor recurrences are rare.

Somatic GNAS Mutation Causes Widespread and Diffuse Pituitary Disease in Acromegalic Patients with McCune-Albright Syndrome

Context: McCune-Albright syndrome (MAS) is caused by sporadic mutations of the GNAS. Patients exhibit features of acromegaly. In most patients, GH-secreting pituitary adenomas have been held responsible for this presentation. However, surgical adenomectomy rarely eliminates excess GH production. Objective: The aim of this study was to elucidate pituitary pathology in patients with MAS and to explain the basis of failure of adenomectomy to eliminate GH hypersecretion. Design and Setting: We conducted a case series at the National Institutes of Health. Intervention(s): Interventions included medical therapy and transsphenoidal surgery. Patients and Main Outcome Measures: We studied clinical and imaging features and the histology and molecular features of the pituitary of four acromegalic MAS patients. Results: We identified widespread and diffuse pituitary gland disease. The primary pathological changes were characterized by hyperplastic and neoplastic change, associated with overrepresentation of somatotroph cells in structurally intact tissue areas. Genetic analysis of multiple microdissected samples of any type of histological area consistently revealed identical GNAS mutations in individual patients. The only patient with remission after surgery received complete hypophysectomy in addition to removal of multiple GH-secreting tumors. Conclusions: These findings indicate developmental effects of GNAS mutation on the entire anterior pituitary gland. The pituitary of individual cases contains a spectrum of changes with regions of normal appearing gland, hyperplasia, and areas of fully developed adenoma formation, as well as transitional stages between these entities. The primary change underlying acromegaly in MAS patients is somatotroph hyperplasia involving the entire pituitary gland, with or without development of somatotroph adenoma. Thus, successful clinical management, whether it is medical, surgical, or via irradiation, must target the entire pituitary, not just the adenomas evident on imaging.

Comparative Proteomic Profiles of Meningioma Subtypes

Meningiomas are classified into three groups (benign, atypical, and anaplastic) based on morphologic characteristics. Atypical meningiomas, which are WHO grade 2 tumors, and anaplastic meningiomas, which are WHO grade 3 tumors, exhibit an increased risk of recurrence and premature death compared with benign WHO grade 1 tumors. Although atypical and anaplastic meningiomas account for <10% of all of meningiomas, it can be difficult to distinguish them from benign meningiomas by morphologic criteria alone. We used selective tissue microdissection to examine 24 human meningiomas and did two-dimensional gel electrophoresis to determine protein expression patterns. Proteins expressed differentially by meningiomas of each WHO grade were identified and sequenced. Proteomic analysis revealed protein expression patterns unique to WHO grade 1, 2, and 3 meningiomas and identified 24 proteins that distinguish each subtype. Fifteen proteins showed significant changes in expression level between benign and atypical meningiomas, whereas nine distinguished atypical from anaplastic meningiomas. Differential protein expression was confirmed by Western blotting and immunohistochemistry. We established differential proteomic profiles that characterize and distinguish meningiomas of increasing grades. The proteins and proteomic profiles enhance understanding of the pathogenesis of meningiomas and have implications for diagnosis, prognosis, and treatment.

Renal cancer in von Hippel–Lindau disease and related syndromes

Sporadic and hereditary forms of renal cell carcinoma (RCC), von Hippel–Lindau (VHL) disease and the familial paraganglioma syndromes are closely related in terms of their clinical, molecular, and genetic aspects. Most RCCs occur sporadically and the heritable fraction of RCC is estimated to be just 2–4%. An understanding of the molecular genetic basis, the disease-specific and gene-specific biology and the clinical characteristics of these cancer syndromes is of utmost importance for effective genetic diagnosis and appropriate treatment. In addition, such insight will improve our understanding of sporadic RCCs. To date, 10 different heritable RCC syndromes have been described. VHL syndrome is the oldest known hereditary RCC syndrome. Similar to VHL disease, phaeochromocytoma is a major manifestation of the paraganglioma syndromes types 1, 3 and 4 in which RCCs have been reported. These syndromes are therefore regarded as VHL-related disorders and are included in this Review. Multifocal tumours, bilateral occurrence, a young age at diagnosis and/or family history are clinical red flags suggestive of hereditary disease and should trigger referral for genetic and molecular analysis. The identification of an underlying genetic alteration enables gene-specific risk assessment and opens up the possibility of a tailored follow-up strategy and specific surveillance protocols as the basis of effective preventive medicine. The important goals of preventive medicine are to increase the life expectancy of affected patients and to improve their quality of life. The study of seemingly rare hereditary syndromes and their susceptibility genes has consistently revealed clues regarding the aetiology and pathogenesis of these diseases, and can aid diagnosis and the development of therapeutics for patients affected by much more common sporadic counterparts.

Identification of a novel proliferation-related protein, WHSC1 4a, in human gliomas

Dynamic changes in the expression of multiple genes appear to be common features that distinguish transformed cells from their normal counterparts. We compared the proteomic profiles of four glioblastoma multiforme (GBM) tissue samples and four normal brain cortex samples to examine the molecular basis of gliomagenesis. Trypsin-digested protein samples were separated by capillary isoelectric focusing with nano-reversed-phase liquid chromatography and were profiled by mass spectrometric sequencing. Wolf-Hirschhorn syndrome candidate 1 (WHSC1), along with 103 other proteins, was found only in the GBM proteomes. Western blot and immunohistochemistry verified our proteomic findings and demonstrated that 30-kDa WHSC1 expression increases with ascending tumor proliferation activity. RNA interference could suppress glioma cell growth by blocking WHSC1 expression. Our novel findings encourage the application of proteomic techniques in cancer research.

Characterization of hemangioblastomas of spinal nerves

OBJECTIVE:Hemangioblastoma is classified as a benign tumor of the central nervous system. Peripheral nervous system hemangioblastomas to date have been described only in a few case reports. Experience in treating patients with these rare lesions, which harbor diagnostic and therapeutic pitfalls, is limited. METHODS:To characterize these lesions better, we reviewed our hemangioblastoma database for patients who underwent surgery for extradural hemangioblastoma of the spinal nerve. RESULTS:Between 1983 and 2003, six patients underwent surgery for spinal nerve hemangioblastomas at our institution. These tumors occurred in 2% of all patients with hemangioblastomas of the central nervous system, or 6% of all patients with spinal hemangioblastomas. The occurrence did not differ in von Hippel-Lindau disease cases versus sporadic cases. Radiographically, the tumors easily could be mistaken for schwannomas or metastases; however, they did have some typical features. If a hemangioblastoma was not suspected primarily, profuse bleeding could complicate surgery. Most of the tumors arose from the dorsal sensory fascicles. The vascular supply was from extradural circulation. In general, the surgical outcome of these lesions was good, and permanent neurological deficit was rare. However, local recurrence was observed in three of six patients. CONCLUSION:These tumors harbor diagnostic and therapeutic pitfalls. In general, the tumors are surgically more challenging, and clinically significant bleeding as well as local tumor recurrence is more common than in intradural hemangioblastomas, mostly because of the frequency of incorrect initial radiographic diagnosis. We suggest that because of the surgical consequences, hemangioblastoma should always be considered to be an important radiological differential diagnosis for nerve sheath tumors. Angiography can bring clarification to ambiguous cases.