Endolymphatic sac tumors in von Hippel—Lindau disease

The genetic differences between types 1 and 2 in von Hippel-Lindau syndrome: comprehensive meta-analysis

BACKGROUND

Patients with von Hippel-Lindau (VHL) disease are at risk of developing tumors in the eye, brain, kidney, adrenal gland, and other organs based on their gene mutations. The VHL tumor suppressor gene contains pathogenic variants responsible for these events. This meta-analysis aims to investigate the genetic differences among the various types of VHL syndrome and their correlation with the location of mutations (exons and domains) in the VHL gene.

METHOD

Papers eligible for publication until September 2023 were identified using the electronic databases of PubMed, Google Scholar, Scopus, and EMBASE. The Random Effect model was utilized to evaluate the genetic differences between type 1 and type 2 VHL syndromes.

RESULTS

The prevalence of missense mutations (MSs) was found to be 58.9% in type 1, while it was 88.1% in type 2. Interestingly, the probability of observing MSs in type 1 was 0.42 times lower compared to type 2. The mutation hotspots of the VHL gene were R167Q/W, Y98H, R238W, and S65L, respectively. Although type 2 had a high presentation of Y98H and R238W, it did not have a higher S65L than type 1. The analysis demonstrated a statistically significant higher prevalence of truncated mutations (PTMs) in type 1. Among type 1, large/complete deletions (L/C DELs) were found in 16.9% of cases, whereas in type 2 only 3.7%. This difference was statistically significant with a p-value < 0.001. Overall, the probability of identifying mutations in domain 2 compared to domain 1 was found to be 2.13 times higher in type 1 (p-value < 0.001). Furthermore, the probability of detecting exon 1 in comparison with observing exon 2 in type 1 was 2.11 times higher than type 2 and revealed a statistically significant result (p-value < 0.001). The detection of exon 2 was 2.18 times higher in type 1 (p-value < 0.001). In addition, the likelihood of discovering exon 2 compared with others was significantly lower in type 1 compared with type 2 VHL (OR = 0.63, p-value = 0.015).

CONCLUSIONS

We have revealed a comprehensive genetic difference between types 1 and 2 of VHL syndrome. The significant differences in MS, PTMs, L/C DELs, and the location of the mutations between type 1 and type 2 VHL patients in the Asian, European, and American populations emphasize the genetic heterogeneity of the syndrome. These findings may pave the way for the diagnosis, treatment, and further investigation of the mechanisms behind this complex genetic disorder.

Third window lesions of the inner ear: A pictorial review

PURPOSE

Radiographic review of pathologies that associate with third window syndrome.

METHODS

Case series and literature review.

RESULTS

Eight unique third window conditions are described and illustrated, including superior, lateral, and posterior semicircular canal dehiscence; carotid-cochlear, facial-cochlear, and internal auditory canal-cochlear dehiscence, labyrinthine erosion from endolymphatic sac tumor, and enlarged vestibular aqueduct.

CONCLUSION

The present study highlights the characteristic imaging features and symptoms to differentiate third window pathologies for expedient diagnosis and management planning.

Guidelines for surveillance of patients with von Hippel-Lindau disease: Consensus statement of the International VHL Surveillance Guidelines Consortium and VHL Alliance

Von Hippel‐Lindau disease is a rare inherited cancer‐predisposition syndrome. The authors report the updated recommendations for the multiorgan surveillance protocols.

Nervous system (NS) Tumors in Cancer Predisposition Syndromes

Genetic syndromes which develop one or more nervous system (NS) tumors as one of the manifestations can be grouped under the umbrella term of NS tumor predisposition syndromes. Understanding the underlying pathological pathways at the molecular level has led us to many radical discoveries, in understanding the mechanisms of tumorigenesis, tumor progression, interactions with the tumor microenvironment, and development of targeted therapies. Currently, at least 7-10% of all pediatric cancers are now recognized to occur in the setting of genetic predisposition to cancer or cancer predisposition syndromes. Specifically, the cancer predisposition rate in pediatric patients with NS tumors has been reported to be as high as 15%, though it can approach 50% in certain tumor types (i.e., choroid plexus carcinoma associated with Li Fraumeni Syndrome). Cancer predisposition syndromes are caused by pathogenic variation in genes that primarily function as tumor suppressors and proto-oncogenes. These variants are found in the germline or constitutional DNA. Mosaicism, however, can affect only certain tissues, resulting in varied manifestations. Increased understanding of the genetic underpinnings of cancer predisposition syndromes and the ability of clinical laboratories to offer molecular genetic testing allows for improvement in the identification of these patients. The identification of a cancer predisposition syndrome in a CNS tumor patient allows for changes to medical management to be made, including the initiation of cancer surveillance protocols. Finally, the identification of at-risk biologic relatives becomes feasible through cascade (genetic) testing. These fundamental discoveries have also broadened the horizon of novel therapeutic possibilities and have helped to be better predictors of prognosis and survival. The treatment paradigm of specific NS tumors may also vary based on the patient's cancer predisposition syndrome and may be used to guide therapy (i.e., immune checkpoint inhibitors in constitutional mismatch repair deficiency [CMMRD] predisposition syndrome) [8]. Early diagnosis of these cancer predisposition syndromes is therefore critical, in both unaffected and affected patients. Genetic counselors are uniquely trained master's level healthcare providers with a focus on the identification of hereditary disorders, including hereditary cancer, or cancer predisposition syndromes. Genetic counseling, defined as "the process of helping people understand and adapt to the medical, psychological and familial implications of genetic contributions to disease" plays a vital role in the adaptation to a genetic diagnosis and the overall management of these diseases. Cancer predisposition syndromes that increase risks for NS tumor development in childhood include classic neurocutaneous disorders like neurofibromatosis type 1 and type 2 (NF1, NF2) and tuberous sclerosis complex (TSC) type 1 and 2 (TSC1, TSC2). Li Fraumeni Syndrome, Constitutional Mismatch Repair Deficiency, Gorlin syndrome (Nevoid Basal Cell Carcinoma), Rhabdoid Tumor Predisposition syndrome, and Von Hippel-Lindau disease. Ataxia Telangiectasia will also be discussed given the profound neurological manifestations of this syndrome. In addition, there are other cancer predisposition syndromes like Cowden/PTEN Hamartoma Tumor Syndrome, DICER1 syndrome, among many others which also increase the risk of NS neoplasia and are briefly described. Herein, we discuss the NS tumor spectrum seen in the abovementioned cancer predisposition syndromes as with their respective germline genetic abnormalities and recommended surveillance guidelines when applicable. We conclude with a discussion of the importance and rationale for genetic counseling in these patients and their families.

Impact of an Endolymphatic Sac Tumor on Subjective and Objective Audiovestibular Function

OBJECTIVE

This study reports subjective and objective audiovestibular function in patients diagnosed with an endolymphatic sac tumor (ELST), to evaluate the clinical implication of vestibular testing in ELST patients.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary referral center/university hospital.

PATIENTS

Five patients diagnosed with unilateral ELST.

INTERVENTION

Subjective and objective audiovestibular tests; pure-tone average; speech discrimination score; the Video Head Impulse Test; the cervical vestibular evoked myogenic potential test; the caloric irrigation test; the Speech, Spatial and Qualities of Hearing Scale; the Tinnitus Handicap Inventory; and the Dizziness Handicap Inventory.

MAIN OUTCOME MEASURE

Findings and characteristics of both subjective and objective audiovestibular functions.

RESULTS

The mean pure-tone average and the mean speech discrimination score were 49 dB HL and 68% on the tumor ear and 13 dB HL and 99% contralaterally. The mean Speech, Spatial and Qualities of Hearing Scale score was 84, and the mean Tinnitus Handicap Inventory score was 64. Caloric testing showed a mean unilateral weakness of 80%. The Video Head Impulse Test of the lateral semicircular canal revealed refixation saccades on all tumor ears and an average gain value of 0.75 on the tumor ear versus 0.94 contralaterally. No cervical vestibular evoked myogenic potentials were elicited on the tumor side, whereas all but one was elicited contralaterally. The average Dizziness Handicap Inventory score was 47.

CONCLUSION

A characteristic pattern of abnormal caloric findings, refixation saccades, and normal vestibulo-ocular reflex gain alongside sensorineural hearing loss on the tumor ear was identified. Asymmetric sensorineural hearing loss in any patient should lead to objective vestibular evaluation to strengthen not only a targeted tumor surveillance strategy and the indication for imaging, but also the design of vestibular rehabilitation. In addition, vestibular findings may guide the choice of surgical approach.

A meta-analysis of different von Hippel Lindau mutations: are they related to retinal capillary hemangioblastoma?

Retinal capillary hemangioblastomas (RCH) is a benign tumor that represents the initial manifestation in roughly half of Von Hippel Lindau (VHL) patients. They may also occur sporadically without systemic involvement. A first meta-analysis study was investigated to estimate the prevalence of Retinal capillary hemangioblastoma (RCH) in Von Hippel Lindau (VHL) syndrome, and its relation to type and location of mutations in VHL gene. The electronic databases of PubMed, Scopus, Embase, and Google Scholar were utilized to find eligible papers published up to May 2020. Lastly, after the different prevalence of RCH in Europe compared to other continents was noted, we decided to consider European and non-European patients separately. The Random effect model was used to evaluate the relation between developing RCH and types of mutations. The overall prevalence of RCH among VHL patients is about 47%. The prevalence of RCH was significantly higher in Europe in comparison with non-Europeans (p value < 0.001). Overall, the differences between the prevalence of RCH among different mutation types were not statistically significant. However, in Europe, the prevalence of RCH was significantly higher in patients with truncation mutation (p value = 0.007). In Europe, the RCH in VHL patients who had a mutation in exon 2 was significantly lower in comparison with exon 1 (p value = 0.001); but in non-Europeans, the prevalence of RCH in VHL patients that involved exon 2 was significantly higher in comparison with VHL patients with a mutation in exon1 (p value = 0.012). The highest risk of developing RCH was reported among Europeans. Overall, this study showed that the prevalence of RCH in VHL syndrome is not related to type or location of mutations and difference of RCH prevalence is probably depends on other genetic or environmental factor that should be considered in subsequent studies.

Endolymphatic Sac Tumor Screening and Diagnosis in von Hippel-Lindau Disease: A Consensus Statement

Objective Endolymphatic sac tumors (ELSTs) are a frequent cause of hearing loss and other audiovestibular dysfunction in patients with von Hippel-Lindau disease (VHL). Unified screening recommendations for VHL patients have not been established. To develop consensus guidelines, the VHL Alliance formed an expert committee to define evidence-based clinical screening recommendations.

Patients and Methods Recommendations were formulated by using the Grading of Recommendations, Assessment, Development, and Evaluation framework after a comprehensive literature review.

Results Diagnosis of ELSTs in VHL requires a combination of clinical evaluation and imaging and audiometric findings. Audiovestibular signs/symptoms are often an early feature of small ELSTs, including those that are not visible on imaging. Diagnostic audiograms have the greatest sensitivity for the detection of ELST-associated sensorineural hearing loss and can help confirm clinically relevant lesions, including those that may not be radiographically evident. Magnetic resonance imaging (MRI) can be a more specific test for ELSTs in VHL particularly when supplemented with computed tomography imaging for the identification of small tumors. VHL patients between the ages 10 and 60 years carry high preponderance for ELST presentation.

Conclusion We recommend that clinical evaluation (yearly) and diagnostic audiograms (every other year) be the primary screening tools for ELSTs in VHL. We suggest that screening be performed between the ages 11 and 65 years or with the onset of audiovestibular signs/symptoms for synchronicity with other testing regimens in VHL. We recommend that baseline imaging (MRI of the internal auditory canals) can be performed between the ages of 15 and 20 years or after positive screening.

Identification of HGD and GSTZ1 as Biomarkers Involved Metabolic Reprogramming in Kidney Renal Clear Cell Carcinoma

Kidney renal clear cell carcinoma (KIRC) with poor prognosis is the main histological subtype of renal cell carcinoma, accounting for more than 80% of patients. Most patients are diagnosed at an advanced stage due to being asymptomatic early on. Advanced KIRC has an extremely poor prognosis due to its inherent resistance to radiotherapy and chemotherapy. Therefore, a comprehensive understanding of the molecular mechanisms of KIRC and the development of effective early diagnostic and therapeutic strategies is urgently needed. In this study, we aimed to identify the prognosis-related biomarker and analyzed its relationship with tumor progression. Metabolic changes are an important feature of kidney cancer, where the reduction of fumarate allows us to target the tyrosine metabolic pathway. The homogentisate 1,2-dioxygenase (HGD) and glutathione S-transferase zeta 1 (GSTZ1) related with prognosis of KIRC was identified through bioinformatics analysis based on The Cancer Genome Atlas (TCGA) databases. Mechanistically, we found that decreased HGD and GSTZ1 promote aerobic glycolysis in KIRC, coordinate the balance of amino acid metabolism and energy metabolism in tumor cells, and ultimately activate the tumor cell cycle and tumor progression. In summary, we identified the tyrosine metabolizing enzymes HGD and GSTZ1 as biomarkers of KIRC, which will further the understanding of the tumor metabolism profile, provide novel strategies and theoretical support for diagnosing and treating KIRC and as referential for future clinical research.

Molecular characterisation of sporadic endolymphatic sac tumours and comparison to von Hippel-Lindau disease-related tumours

AIMS

Although inactivation of the von Hippel-Lindau gene (VHL) on chromosome 3p25 is considered to be the major cause of hereditary endolymphatic sac tumours (ELSTs), the genetic background of sporadic ELST is largely unknown. The aim of this study was to determine the prevalence of VHL mutations in sporadic ELSTs and compare their characteristics to VHL-disease-related tumours.

METHODS

Genetic and epigenetic alterations were compared between 11 sporadic and 11 VHL-disease-related ELSTs by targeted sequencing and DNA methylation analysis.

RESULTS

VHL mutations and small deletions detected by targeted deep sequencing were identified in 9/11 sporadic ELSTs (82%). No other cancer-related genetic pathway was altered except for TERT promoter mutations in two sporadic ELST and one VHL-disease-related ELST (15%). Loss of heterozygosity of chromosome 3 was found in 6/10 (60%) VHL-disease-related and 10/11 (91%) sporadic ELSTs resulting in biallelic VHL inactivation in 8/10 (73%) sporadic ELSTs. DNA methylation profiling did not reveal differences between sporadic and VHL-disease-related ELSTs but reliably distinguished ELST from morphological mimics of the cerebellopontine angle. VHL patients were significantly younger at disease onset compared to sporadic ELSTs (29 vs. 52 years, p < 0.0001, Fisher's exact test). VHL-disease status was not associated with an increased risk of recurrence, but the presence of clear cells was found to be associated with shorter progression-free survival (p = 0.0002, log-rank test).

CONCLUSION

Biallelic inactivation of VHL is the main mechanism underlying ELSTs, but unknown mechanisms beyond VHL may rarely be involved in the pathogenesis of sporadic ELSTs.

Papillary-cystic neoplasms of the middle ear are distinct from endolymphatic sac tumours

AIMS

Papillary neoplasms of the middle and inner ear are rare and poorly characterised. The current World Health Organization classification divides them into two major subtypes: aggressive papillary tumours (APTs) and endolymphatic sac tumours (ELSTs). The aim of this article is to present two papillary neoplasms of the middle ear that do not fit into either the classic APT category or the classic ELST category, and compare them with three ELSTs.

METHODS AND RESULTS

The patients were a 48-year-old female and a 59-year-old male without a history of other neoplasms. Histology showed papillary-cystic growth of predominantly oncocytic (Case 1) or mucinous (Case 2) cells surrounded by a p63-positive basal layer. The overall histology was reminiscent of oncocytic sinonasal papilloma (Case 1) and pancreatobiliary or salivary intraductal papillary mucinous neoplasms (Case 2). Ovarian-type stroma, invasion and malignant features were absent. Immunohistochemistry revealed expression of cytokeratin (CK) 7, but not carbonic anhydrase IX (CAIX) or paired box gene 8 (PAX8) (except for very focal PAX8 expression in Case 1). The TST15 gene panel and HRAS sequencing revealed no pathogenic mutations in BRAF, KRAS, EGFR, AKT1, or HRAS. The TruSight RNA fusion panel revealed an MKRN1-BRAF fusion in Case 1. No fusion was detected in Case 2. The three ELSTs showed classic features of the entity, expressed CK7, epithelial membrane antigen, PAX8, and CAIX, and lacked a basal cell layer.

CONCLUSION

These novel cases suggest that papillary tumours of the ear represent a heterogeneous spectrum of distinct neoplasms unified by a prominent papillary-cystic pattern rather than a single entity. Future studies should clarify whether the MKRN1-BRAF fusion is a defining recurrent driver event, especially in those cases reported as sinonasal-type middle ear papillomas.

Clinical response to pazopanib in a patient with endolymphatic sac tumor not associated with von Hippel-Lindau syndrome

Endolymphatic sac tumors (ELSTs) are rare, locally invasive, vascular tumors of the temporal bone. These lesions are associated with von Hippel-Lindau syndrome but may arise sporadically. Early surgical intervention is recommended to prevent permanent neurologic deficits; however, many ELSTs are unresectable or are subtotally resected due to neurovascular compromise. Chemotherapeutic salvage therapy in trials of neoplasms of associated syndromes has targeted angiogenesis with variable response. We present the case of a sporadic ELST, previously minimally responsive to bevacizumab, treated with pazopanib, a multi-kinase inhibitor and antiangiogenic, with good response. Cases such as our patient may demonstrate the utility of novel antiangiogenics in the treatment of these rare neoplasms, particularly when the tumor is unresectable or necessitates subtotal resection.

Endolymphatic sac tumor at the cerebellopontine angle: A case report and review of literature

INTRODUCTION

Endolymphatic sac tumors may present as sporadic or may be associated with Von Hippel-Lindau disease. Patients generally present with hearing loss, tinnitus and vertigo. The tumor is highly vascular which may lead to erosion of the adjacent bony and vascular structures, resulting in heavy bleeding during surgery.

PRESENTATION

A twenty-five year-old female presented with a five year history of chronic ear discharge, left sided facial weakness, and recent onset of ataxia.

DISCUSSION

The unusual clinical presentation made management challenging, in large part due to profuse bleeding. Pre-operative embolization of the vessels supplying the tumor may reduce blood loss during surgical excision. Radiotherapy could be considered for any residual tumor.

CONCLUSION

The patient was diagnosed with an endolymphatic sac tumor of sporadic origin which presented at the cerebellopontine angle and was managed with a multidisciplinary approach.

Endolymphatic sac tumour in von Hippel-Lindau disease: management strategies

Endolymphatic sac tumour (ELST) is infrequent, as emerges from small series reported in the literature. It is a slow-growing malignancy with local aggressiveness and a low risk of distant metastases. It is often misdiagnosed because of the late onset of symptoms and difficulty in obtaining a biopsy. Its frequency is higher in von Hippel-Lindau (VHL) disease (a genetic systemic syndrome involving multiple tumours), with a prevalence of around 25%. The diagnosis is based on radiology, with specific patterns on contrast-enhanced MRI and typical petrous bone erosion on bone CT scan. Our experience of ELST in the years between 2012-2015 concerns 7 cases, one of which was bilateral, in patients with VHL disease. Four of the 7 patients underwent 5 surgical procedures at our institution. Each case is described in detail, including clinical symptoms, and the intervals between symptom onset, diagnosis and therapy. Postoperative morbidity was low after early surgery on small tumours, whereas extensive surgery for large tumours was associated with loss of cranial nerve function (especially VII, IX, X). The critical sites coinciding with loss of neurological function were the fallopian canal, jugular foramen, petrous apex and intradural extension into the posterior cranial fossa. Early surgery on small ELST is advocated for patients with VHL disease, in whom screening enables a prompt diagnosis and consequently good prognosis.

A histopathological connection between a fatal endolymphatic sac tumour and von Hippel-Lindau disease from 1960

OBJECTIVE

To highlight a case from 1960 connecting endolymphatic sac tumour and von Hippel-Lindau disease.

CASE REPORT

In 1960, a 24-year-old woman presented with unilateral hearing loss, pulsatile tinnitus and a mass visible on otoscopy. The patient underwent surgical biopsy, which was complicated by haemorrhage, and ultimately resulted in death. At autopsy, a destructive temporal bone neoplasm with cystic and papillary architecture was observed that had eroded into the otic capsule. Intra-abdominal lesions consistent with von Hippel-Lindau disease were also observed, and the surgeon postulated a connection between endolymphatic sac tumour and von Hippel-Lindau disease.

METHOD

A review of the literature was carried out using PubMed.

CONCLUSION

Endolymphatic sac tumours are rare neoplasms of the temporal bone that can occur sporadically or as part of von Hippel-Lindau disease. The connection between endolymphatic sac tumour and von Hippel-Lindau disease was first proposed in 1988 and formalised in 1997. We believe that this case represents the first documented connection between endolymphatic sac tumour and von Hippel-Lindau disease.

A Comprehensive Review of Pediatric Tumors and Associated Cancer Predisposition Syndromes

An understanding of the role of inherited cancer predisposition syndromes in pediatric tumor diagnoses continues to develop as more information is learned through the application of genomic technology. Identifying patients and their relatives at an increased risk for developing cancer is an important step in the care of this patient population. The purpose of this review is to highlight various tumor types that arise in the pediatric population and the cancer predisposition syndromes associated with those tumors. The review serves as a guide for recognizing genes and conditions to consider when a pediatric cancer referral presents to the genetics clinic.

Von Hippel-Lindau Disease

Von Hippel-Lindau disease is an autosomal dominant syndrome which occurs secondary to germline mutations in the VHL tumor suppressor gene, located on chromosome 3. Clinically von Hippel-Lindau disease is characterized by an increased risk of developing simple visceral cysts, most commonly in the pancreas and kidneys, in addition to an increased risk of developing neoplasms, often with clear cell features, in a multitude of organ systems. The most common neoplasms are cerebellar and retinal hemangioblastomas, adrenal pheochromocytomas, clear cell renal cell carcinomas, pancreatic neuroendocrine tumors, pancreatic serous cystadenomas, and endolymphatic sac tumors. These lesions most commonly present during adulthood; however, screening and surveillance for the development of these lesions should begin in the pediatric years for patients with von Hippel-Lindau disease. In this review article, the genetics and most common neoplasms of von Hippel-Lindau disease are reviewed, with an eye towards implications for the pediatric patient.

von Hippel-Lindau Disease: Review of Genetics and Imaging

von Hippel-Lindau (VHL) disease is an autosomal-dominant, hereditary, multisystem neoplasia syndrome with increased susceptibility to several benign and malignant tumors. VHL occurs in about 1 in 36,000 live births and is associated with germline mutation of the VHL tumor suppressor gene on the short arm of chromosome 3. VHL disease exhibits diverse genotype and phenotype correlations, exhibits variable intrafamilial and interfamilial expressivity, and can manifest with benign and malignant tumors of the central nervous system, kidneys, adrenals, pancreas, and reproductive organs. Imaging and management of this entity are therefore multidisciplinary. An overview of VHL disease is presented.

Von Hippel-Lindau disease

von Hippel-Lindau (VHL) disease is an inheritable condition with an incidence of 1 in 36000 live births. Individuals with VHL develop benign and malignant tumors including retinal and central nervous system hemangioblastomas, clear cell renal cell carcinomas (RCC), pheochromocytomas, pancreatic neuroendocrine tumors and endolymphatic sac tumors (ELSTs). VHL is caused by germline loss of function of the VHL gene on one allele at chromosome 3p25-26. A somatic "second hit" event leads to the loss of the other allele and tumor formation. Loss of VHL function in cells leads to increased expression and stabilization of hypoxia inducible factor (HIF). VHL protein/HIF pathway has been implicated in tumorigenesis for hemangioblastomas, RCC and other VHL tumors. Clinical examination, imaging, and genetic testing for VHL mutations confirm VHL disease. Management of VHL disease largely consists of surgical resection of symptomatic tumors (hemangioblastomas), tumors prone to metastasize (RCC larger than 3cm), or tumors causing hormonal symptoms (pheochromocytomas). Despite advances in early diagnosis and management of VHL disease, life expectancy for VHL patients remains low at 40-52 years. Secondary effects from VHL manifestations are mitigated by routine surveillance and early detection. In this chapter, we summarize the current state of knowledge in VHL disease.

De novo development and progression of endolymphatic sac tumour in von hippel-lindau disease: an observational study and literature review

Endolymphatic sac tumors (ELST) are rare invasive lesions of the temporal bone that are commonly associated with von Hippel-Lindau disease. This report describes serial magnetic resonance imaging (MRI) and computed tomography (CT) findings over a period of 6 years in a 12-year-old patient who developed an ELST after 3.5 years surveillance for a cerebellar hemangioblastoma. A 1.5 × 8 mm tumor was identified on MRI within the endolymphatic duct when the patient presented with audiovestibular symptoms due to intralabyrinthine hemorrhage. The tumor demonstrated subsequent growth over 25 months until the patient agreed to undergo surgical resection by subtotal petrosectomy. De novo development and the natural history have been described only in six previous cases. MRI is regarded to be unreliable with respect to the ability to demonstrate an ELST in the presence of intralabyrinthine hemorrhage, with only two out of four previously reported patients demonstrating positive MRI findings. Little is known about the precise origin (endolymphatic duct versus sac), growth, and symptom correlation. This case highlights that new audiovestibular symptoms are a potential clinical clue and intralabyrinthine hemorrhage is a neuroimaging indicator for the presence of an ELST, which based on high-resolution MRI appears to originate in the endolymphatic duct rather than sac.

Imaging detection of endolymphatic sac tumor–associated hydrops

Object

To determine if physiologically based MRI sequences can be used to detect endolymphatic sac tumor (ELST)–associated hydrops, the authors performed contrast-enhanced delayed FLAIR imaging in consecutive ELST patients with clinical findings consistent with hydrops.

Methods

Consecutive patients with von Hippel-Lindau (VHL) disease and clinical findings of endolymphatic hydrops and ELSTs underwent contrast-enhanced delayed FLAIR MRI. Clinical, audiological, operative, and imaging findings were analyzed.

Results

Three patients (2 male, 1 female) with 4 ELSTs (1 patient had bilateral ELSTs) were identified who had clinical findings consistent with endolymphatic hydrops. Computed tomography and MRI evidence of an ELST was found in all patients. Their mean age at initial evaluation was 39.7 years (range 28–51 years). All patients demonstrated progressive sensorineural hearing loss that was associated with episodic vertigo and tinnitus. Contrast-enhanced delayed FLAIR MRI clearly demonstrated dilation of the membranous labyrinth consistent with hydrops in the affected ears but not the unaffected ears. Two patients underwent resection of the associated ELST that resulted in stabilization of progressive hearing loss, as well as amelioration of tinnitus and vertigo.

Conclusions

Contrast-enhanced delayed FLAIR MRI can be used to detect ELST-associated hydrops. Noninvasive MRI detection of hydrops can permit earlier detection of ELSTs in patients with VHL disease and provides direct insight into a mechanism that underlies ELST-associated audiovestibular morbidity.

Nervous system involvement in von Hippel-Lindau disease: pathology and mechanisms

Patients with von Hippel-Lindau disease carry a germline mutation of the Von Hippel-Lindau (VHL) tumor-suppressor gene. We discuss the molecular consequences of loss of VHL gene function and their impact on the nervous system. Dysfunction of the VHL protein causes accumulation and activation of hypoxia inducible factor (HIF) which can be demonstrated in earliest stages of tumorigenesis and is followed by expression of VEGF, erythropoietin, nitric oxide synthase and glucose transporter 1 in VHL-deficient tumor cells. HIF-independent functions of VHL, epigenetic inactivation of VHL, pVHL proteostasis, and links between loss of VHL function and developmental arrest are also described. A most intriguing feature in VHL disease is the occurrence of primary hemangioblastic tumors in the nervous system, the origin of which has not yet been entirely clarified, and current hypotheses are discussed. Endolymphatic sac tumors may extend into the brain, but originally arise from proliferation of endolymphatic duct/sac epithelium; the exact nature of the proliferating epithelial cell, however, also has remained unclear, as well as the question why tumors almost consistently develop in the intraosseous portion of the endolymphatic sac/duct only. The epitheloid clear cell morphology of both advanced hemangioblastoma and renal clear cell carcinoma can make the differential diagnosis challenging, recent developments in immunohistochemical differentiation are discussed. Finally, metastasis to brain may not only be caused by renal carcinoma, but may derive from VHL disease-associated pheochromocytoma/paraganglioma, or pancreatic neuroendocrine tumor.

The metabolic basis of kidney cancer

Kidney cancer is not a single disease; it is made up of a number of different types of cancer that occur in the kidney. Each of these different types of kidney cancer can have a different histology, have a different clinical course, can respond differently to therapy and is caused by a different gene. Kidney cancer is essentially a metabolic disease; each of the known genes for kidney cancer, VHL, MET, FLCN, TSC1, TSC2, TFE3, TFEB, MITF, fumarate hydratase (FH), succinate dehydrogenase B (SDHB), succinate dehydrogenase D (SDHD), and PTEN genes is involved in the cells ability to sense oxygen, iron, nutrients or energy. Understanding the metabolic basis of kidney cancer will hopefully provide the foundation for the development of effective forms of therapy for this disease.

Surgical resection of endolymphatic sac tumors in von Hippel-Lindau disease: findings, results, and indications

OBJECTIVES/HYPOTHESIS

To define the surgical treatment and outcomes of von Hippel-Lindau (VHL) disease-associated endolymphatic sac tumors (ELSTs), we analyzed consecutive VHL patients who underwent ELST resection.

STUDY DESIGN

Retrospective investigation of consecutive VHL patients who underwent resection of ELSTs at a clinical research center between 1999 and 2010.

METHODS

Analysis of serial clinical examinations, audiograms, imaging studies, and operative findings were analyzed.

RESULTS

Thirty-one consecutive patients with ELSTs (15 males, 16 females) underwent resection of 33 tumors (mean follow-up, 49.9 ± 48.0 months; range, 1.0-116 months). One patient had bilateral ELST resections and one patient underwent reoperation for recurrence. Mean age at surgery was 38.2 ± 10.2 years (range, 12-67 years). Whereas 29 ears (88%) had direct radiographic evidence of an ELST, four ears (12%) did not. Mean tumor size was 1.3 ± 1.1 cm (range, 0.2-5.2 cm). Whereas two patients (two ears, 6%) were asymptomatic, 29 patients (31 ears, 94% of ears) had associated audiovestibular symptoms, including sensorineural hearing loss (28 ears, 84%), tinnitus (24 ears,73%), and vertigo (21 patients, 68%). Postoperatively, hearing was stabilized (27) or improved (three) in 97% of 31 ears. Complete tumor resection was achieved in 30 ears (91% of 33 ears). Complications included cerebrospinal fluid leak in two ears (6%) and transient lower cranial nerve palsy in one ear (3%).

CONCLUSIONS

Surgical resection of ELSTs can be performed with hearing preservation and a reduction in audiovestibular dysfunction. Early surgical resection can prevent or decrease disabling audiovestibular symptoms, enhance the opportunity for complete resection, and preserve hearing.

Von Hippel-Lindau: how a rare disease illuminates cancer biology

Von Hippel-Lindau (VHL) disease is a rare autosomal dominant syndrome (1/36,000 live births) with highly penetrance that predispose to the development of a panel of highly vascularized tumors (model of tumoral angiogenesis). Main manifestations include central nervous system (CNS) and retinal haemangioblastomas, endolymphatic sac tumors, clear-cell renal cell carcinomas (RCC), phaeochromocytomas and pancreatic neuroendocrine tumors. RCC has become the first potential cause of mortality and VHL disease is the main cause of inherited RCC. The disease is caused by germline mutations in the VHL tumor-suppressor gene that plays a major role in regulation of the oxygen-sensing pathway by targeting the hypoxia-inducible factor HIF for degradation in proteasome. VHL has also major HIF-independent functions, specially in regulation of primary cilium, extracellular matrix and apoptosis. Somatic inactivation of the VHL gene is the main molecular event in most sporadic RCC and the treatment of advanced RCC has been revolutionized by targeted therapy with drugs that block angiogenesis. These drugs are now in first line in metastatic sporadic RCC and have shown promising results for RCC, pancreatic neuroendocrine tumors and malignant pheochromocytomas in VHL patients.

von Hippel-Lindau disease: surveillance strategy for endolymphatic sac tumors

PURPOSE

: Up to 16% of patients with the hereditary von Hippel-Lindau disease develop endolymphatic sac tumors of the inner ear. Early diagnosis and treatment of endolymphatic sac tumors can prevent audiovestibular morbidity, but optimal endolymphatic sac tumor surveillance strategy has yet to be determined. We aimed to evaluate endolymphatic sac tumor surveillance to determine the best surveillance strategy.

METHODS

: In a national prospective study, 40 VHL mutation carriers were interviewed about audiovestibular symptoms and had audiological examinations and magnetic resonance imaging of the inner ear. Further, we performed a meta-analysis including all reported endolymphatic sac tumor von Hippel-Lindau disease cases in the literature (N = 140 with 156 endolymphatic sac tumors).

RESULTS

: In the prospective study, endolymphatic sac tumors were suspected based on audiovestibular symptoms, audiometry, and magnetic resonance imaging in 34%, 30%, and 12.5% of subjects, respectively. In total, more than 90% of radiologically diagnosed endolymphatic sac tumors were associated with abnormal audiometric findings. No endolymphatic sac tumor genotype-phenotype correlations were found.

CONCLUSION

: We recommend annual audiometry as a first-line endolymphatic sac tumor screening tool, and in countries where periodic surveillance magnetic resonance imaging of the central nervous system is performed, specific images of the inner ear should be included. Audiometric abnormalities in patients with von Hippel-Lindau disease without magnetic resonance imaging-visible endolymphatic sac tumors could be due to microscopic endolymphatic sac tumors. Determination of audiometric endolymphatic sac tumor characteristics could further target screening and improve endolymphatic sac tumor diagnosis.

Endolymphatic sac tumor: case report and review of the literature

Endolymphatic sac tumor (ELST) is a rare neoplasm which can be encountered sporadically or in Von Hippel-Lindau (VHL) disease. Here we report a sporadic case of ELST in 31-year-old man. Neither the symptoms nor a family history of VHL disease were found in the patient. CT imaging demonstrated an expansile lytic lesion of the mastoid process of the left petrous bone. MR scanning revealed a 5.2 cm × 4.7 cm × 4.2 cm mass which showed hyperintensity on T1- and T2-weighted images. Histologic sections showed a papillary, cystic or glandular architecture. The papillary and glandular structures were lined by a single layer of flattened cuboidal-to-columnar cells. The stroma of the papillary fronds was richly vascularized and chronically inflamed. The tumor showed diffusely positive reactivity with cytokeratin (Pan), cytokeratin 19, cytokeratin 5/6, cytokeratin 7, EMA, vimentin, CD56, and NSE and also showed variable reactivity with glial fibrillary acidic protein (GFAP) and VEGF. The Ki-67 immunostain showed a proliferation index of < 1%. Because the mass was large, it was difficult to extirpate surgically. After surgery, the patient underwent gamma-knife radiosurgery for residual tumor. The findings indicate that ELST is a rare neoplasm with benign histopathological appearance and clinically destructive behavior. Because of the rarity of this tumor, it can easily be confused with other tumors such as paraganglioma, middle ear adenoma, adenocarcinoma, papillary carcinoma of thyroid or choroid plexus papilloma. Owing to its locally aggressive nature, it is difficult to extirpate surgically when it is large.

Management of von Hippel-Lindau disease-associated CNS lesions

Patients with von Hippel-Lindau disease (VHL) often harbor significant disease burden within the CNS, specifically craniospinal-axis hemangioblastomas and endolymphatic sac tumors (ELSTs). The majority (60-80%) of patients with VHL harbor hemangioblastomas, and 10-15% will develop ELSTs. Advances in the understanding of the natural history and outcomes associated with the surgical management of VHL-associated tumors have led to improved management of patients with VHL. Optimizing indications for surgical intervention and refining of surgical techniques for these lesions can reduce patient morbidity associated with the management of this syndrome. In this article, we review the various aspects of perioperative management of patients with VHL, surgical indications and general operative principles for the management of hemangioblastomas and ELSTs, and outcomes associated with the surgical treatment of these tumors.

Neurosurgical considerations in von Hippel-Lindau disease

Von Hippel-Lindau disease is an inherited syndrome predisposing to a variety of benign and malignant neoplasms of the central nervous system and viscera that requires comprehensive screening and follow-up of individuals and their families. As such, it is important for the neurosurgeon to be aware of its clinical features and management issues. In this article we review the clinical aspects, management and surveillance of von Hippel-Lindau disease for neurosurgical practice.

Conservative management of endolymphatic sac tumors in von Hippel-Lindau disease: case report

In endolymphatic sac tumors associated with von Hippel-Lindau disease, early detection and surgery have been warranted to avoid associated neurological morbidity. However, in lately discovered tumors, hearing preserving surgery is often impossible and timing of surgical resection is difficult to define. We report two cases of tumors revealed by a sudden and profound hearing loss and managed conservatively for more than 15 years without worsening of the neurological symptoms associated with the endolymphatic sac tumor. Tumor size remained stable for the first patient and a stuttering growth pattern was observed for the second patient. Initial observation may be considered a not unreasonable management paradigm in these cases.

Hereditary kidney cancer: unique opportunity for disease-based therapy

Kidney cancer is not a single disease; it is comprised of several different types of cancer, each with a different histology, with a different clinical course, caused by a different gene, and responding differently to therapy. The VHL gene is the gene for the hereditary cancer syndrome, von Hippel-Lindau, as well as for the common form of sporadic, noninherited, clear cell kidney cancer. Understanding the VHL-hypoxia inducible factor (HIF) pathway has provided the foundation for the development of several agents targeting this pathway, such as sunitinib, sorafenib, and temsirolimus. Hereditary papillary renal carcinoma (HPRC) is a hereditary renal cancer syndrome in which affected individuals are at risk for the development of bilateral, multifocal, type 1 papillary renal cell carcinoma. The genetic defect underlying HPRC is MET, the cell surface receptor for hepatocyte growth factor. Mutations of MET also have been identified in a subset of tumors from patients with sporadic type 1 papillary renal cell carcinoma (RCC). Clinical trials targeting the MET pathway are currently underway in patients with HPRC and in patients with sporadic (nonhereditary) papillary kidney cancer. The BHD gene (also known as folliculin or FLCN) is the gene for Birt-Hogg-Dube syndrome, an autosomal-dominant genodermatosis associated with a hereditary form of chromophobe and oncocytic, hybrid RCC. Preclinical studies are underway targeting the BHD gene pathway in preparation for clinical trials in Birt-Hogg-Dube and sporadic chromophobe RCC. Patients with hereditary leiomyomatosis RCC (HLRCC) are at risk for developing cutaneous and uterine leiomyomas and a very aggressive type of RCC. HLRCC is characterized by germline mutation of the Krebs cycle enzyme, fumarate hydratase (FH). Studies of the tricarboxylic acid cycle and the VHL-HIF pathways have provided the foundation for therapeutic approaches in patients with HLRCC-associated kidney cancer as well as other hereditary and sporadic forms of RCC.

Neurologic manifestations of von Hippel-Lindau disease

von Hippel-Lindau disease (VHL) is an autosomal-dominant neoplasia syndrome that is the result of a germline mutation of the VHL tumor suppressor gene on the short arm of chromosome 3. Patients with VHL are predisposed to develop lesions of the central nervous system and viscera. Central nervous system lesions include hemangioblastomas (the most common tumor in VHL) and endolymphatic sac tumors (ELSTs). Visceral manifestations include renal carcinomas and cysts, pancreatic neuroendocrine tumors and cysts, pheochromocytomas, and cystadenomas of the reproductive adnexal organs. Despite their benign pathology, hemangioblastomas and ELSTs are a frequent cause of morbidity and mortality in patients with VHL. Recent molecular biologic investigations into these VHL-associated central nervous system lesions provide new insight into their origin and development. Emerging data from serial imaging and clinical surveillance protocols provide insight into the natural history of these lesions. Because of the dissimilar pathobiology and clinical course between hemangioblastomas and ELSTs, the optimal management strategies for these neurologic manifestations of VHL are very different.

The vestibular aqueduct: site of origin of endolymphatic sac tumors

OBJECT

Although endolymphatic sac tumors (ELSTs) frequently destroy the posterior petrous bone and cause hearing loss, the anatomical origin of these neoplasms is unknown. To determine the precise topographic origin of ELSTs, the authors analyzed the imaging, operative, and pathological findings in patients with von Hippel-Lindau disease (VHL) and ELSTs.

METHODS

Consecutive VHL patients with small (<or= 1.5 cm) ELSTs who underwent resection at the National Institutes of Health were included. Clinical, imaging, operative, and pathological findings were analyzed.

RESULTS

Ten consecutive VHL patients (6 male and 4 female) with 10 small ELSTs (<or= 1.5 cm; 9 left, 1 right) were included. Serial imaging captured the development of 6 ELSTs and revealed that they originated within the intraosseous (vestibular aqueduct) portion of the endolymphatic duct/sac system. Imaging just before surgery demonstrated that the epicenters of 9 ELSTs (1 ELST was not visible on preoperative imaging) were in the vestibular aqueduct. Inspection during surgery established that all 10 ELSTs were limited to the intraosseous endolymphatic duct/sac and the immediately surrounding region. Histological analysis confirmed tumor within the intraosseous portion (vestibular aqueduct) of the endolymphatic duct/sac in all 10 patients.

CONCLUSIONS

ELSTs originate from endolymphatic epithelium within the vestibular aqueduct. High-resolution imaging through the region of the vestibular aqueduct is essential for diagnosis. Surgical exploration of the endolymphatic duct and sac is required for complete resection.

Endolymphatic sac tumor as initial manifestation of von hippel-lindau syndrome

PURPOSE

To report endolymphatic sac tumor (ELST) as the initial finding in von Hippel-Lindau (VHL) syndrome.

METHODS

Case report.

RESULTS

A 4-year-old boy presented in February 2001 with right hearing loss and seventh nerve palsy from ELST. Genetic analysis showed a VHL mutation (gene 3p25-26). Systemic and ocular examination for VHL syndrome-related tumors was unrevealing. Four years later, multiple retinal hemangioblastoma (retinal capillary hemangioma) were detected in both eyes and successfully treated with argon laser photocoagulation.

CONCLUSION

ELSTs can be the initial manifestation of VHL syndrome. Lifelong screening for related tumors, particularly retinal hemangioblastoma, is advised.

Origin of endolymphatic sac tumor

Autopsy temporal bone sections showing a one mm papillary glandular neoplasm, confined to the left endolymphatic duct, are described. This is the second literature report confirming the post-mortem site of origin of the "endolymphatic sac tumor". The patient died after surgery for right vestibular schwannoma, but no features of von Hippel Lindau disease or neurofibromatosis 2 had been displayed clinically or at autopsy. A study of the epithelium of normal human mature endolymphatic ducts and sacs (EDSs) in archival temporal bone sections showed hyperplastic tubular outgrowths, usually situated in the intraosseous portion of the endolymphatic sac, in most cases. Such appearances imply that the epithelium of the EDS has the potential of producing a malignant papillary glandular neoplasm. Papillary ingrowths, some forming collagenous polypoid projections, and cysts were frequent among the epithelial cells. Psammoma bodies were present in the ducts and sacs of older patients. Appearances suggesting erosion of the bony interface of vestibular aqueduct with EDS could be ascribed to the entry and exit of blood vessels into and from the vestibular aqueduct. Care should be taken in the evaluation of surgical or autopsy material from EDSs not to overcall any of these normal features as malignant.

Endolymphatic sac tumor demonstrated by intralabyrinthine hemorrhage

✓ Endolymphatic sac tumors (ELSTs) are locally invasive neoplasms that arise in the posterior petrous bone and are associated with von Hippel–Lindau (VHL) disease. These tumors cause symptoms even when microscopic in size (below the threshold for detectability on imaging studies) and can lead to symptoms such as hearing loss, tinnitus, vertigo, and facial nerve dysfunction. While the mechanisms of audiovestibular dysfunction in patients harboring ELSTs are incompletely understood, they have critical implications for management. The authors present the case of a 33-year-old man with VHL disease and a 10-year history of progressive tinnitus, vertigo, and left-sided hearing loss. Serial T1-weighted magnetic resonance (MR) imaging and computed tomography scans revealed no evidence of tumor, but fluid attenuated inversion recovery (FLAIR) MR imaging sequences obtained after hearing loss demonstrated evidence of left intralabyrinthine hemorrhage. On the basis of progressive disabling audiovestibular dysfunction (tinnitus and vertigo), FLAIR imaging findings, and VHL disease status, the patient underwent surgical exploration of the posterior petrous region, and a small (2-mm) ELST was identified and completely resected. Postoperatively, the patient had improvement of the tinnitus and vertigo. Intralabyrinthine hemorrhage may be an early and the only neuroimaging sign of an ELST in patients with VHL disease and audiovestibular dysfunction. These findings support tumor-associated hemorrhage as a mechanism underlying the audiovestibular dysfunction associated with ELSTs.

Small papillary tumor in the saccule

Papillary tumors of the ear are aggressive neoplasms. Previously, a tumor growing in the saccule had not been reported. We report a tumor found incidentally in the saccule of a patient. Serial sections of both temporal bones of the patient were studied in order to analyze the tumor's origin and influence on audio vestibular function. In the right inner ear, there was a small papillary lesion in the saccule, which looked like a papillary tumor without aggression invasion. The tumor was located in the membranous labyrinth of the saccule, not in the endolymphatic duct and sac. It was not related to Von Hippel-Lindau (VHL) disease, nor was it an endolymphatic sac tumor. The tumor did not influence the hearing and vestibular function in the right ear, although this patient presented a severe sensorineural hearing loss and vestibular function loss because of the vestibular schwannoma in the left ear.

Evaluation and Management of Endolymphatic Sac and Duct Tumors

The endolymphatic sac tumor is a slow-growing, locally aggressive neoplasm that originates from the epithelium of the endolymphatic sac and duct. Disease progression can lead to profound sensorineural hearing loss, posterior fossa invasion, brainstem compression, drop metastasis, and eventual death. Early diagnosis and surgical attention are the primary objectives in the management of patients who have endolymphatic sac tumor. This article describes the latest rationale and techniques for hearing preservation surgery and a review of the latest developments surrounding this disease entity.