Endolymphatic sac tumor misdiagnosed as metastatic renal cell carcinoma: Pitfalls in morphology and immunohistochemistry.

Endolymphatic sac tumor (ELST) is a rare disease that originates from the endolymphatic sac system of the inner ear. Being a low-grade malignant tumor, ELST has a mild morphology and is characterized by a slow but aggressive growth. Most clinicians and pathologists are unfamiliar with this disease. ELST can be misdiagnosed as metastatic renal cancer because of the similarity in morphology and expression of nephrogenic markers such as PAX8. The presented case of a 27-year-old man revealed that observing the characteristic location and confirming the absence of renal neoplasm to rule out the possibility of metastasis are critical for obtaining an accurate final diagnosis.

A New Methodology for Evaluation of Large Vestibular Aqueduct in CT and MRI Images.

HYPOTHESIS: Development of a new method for large vestibular aqueduct (LVA)/large endolymphatic sac anomaly (LESA) assessment using magnetic resonance imaging (MRI) and computed tomography (CT)/cone beam CT (CBCT) images. The secondary objective was to compare both modalities. BACKGROUND: The gold standard for LVA diagnosis is the analysis of CT images using Valvassori and Clemis or Cincinnati criteria. The previous studies showed inconclusive results regarding the correlation between audiological and radiological data. METHODS: Retrospective analysis of radiological images from 173 patients (315 ears), who were diagnosed with LVA/LESA based on CT/CBCT and/or MRI images of the temporal bone. The images obtained using both techniques were used to measure the following dimensions of vestibular aqueduct (VA)/endolymphatic duct (ED)/intraosseous endolymphatic sac (ES): width of the opening, length, and width at external aperture. In MRI images, the maximal contact diameters of the extraosseous or intraosseous ES and dura mater were measured as well. RESULTS: LVA has been reported to be bilateral in 82% (142 patients) and unilateral in 18% (31 patients) of cases. Comparison of MRI and CT/CBCT measurements showed a moderate correlation (0.64) in external aperture, a moderate correlation (0.57) in the width of the VA opening, and a weak correlation (0.34) in length measurements (p < 0.05). CONCLUSION: We developed a new method to identify the heterogeneous pathology of LVA/LESA using reconstruction along the VA/ED/intraosseous ES axis, three measurements on two planes, and focus on the maximal contact diameter between the extraosseous or intraosseous ES and dura mater.

A Rare Case of Angiofibroma Presenting as an Endolymphatic Sac Tumor.

A 30-year-old man presented with minute-long episodes of vertigo and severe autophony. CVEMP showed a decreased threshold when testing the left side, potentially indicating SSCD. A subsequent MRI demonstrated a multi-lobulated, cystic mass in the temporal bone and the radiological diagnosis at that time was ELST. Tumor excision was performed, and microscopic examination of the excised material revealed fibrovascular tissue without signs of papillary or cystic projections. The conclusion of the histological assessment rendered a diagnosis of angiofibroma. We were unable to find a previous report of ENA originating around the endolymphatic sac. Laryngoscope, 134:1897-1900, 2024.

Radiological feature heterogeneity supports etiological diversity among patient groups in Meniere's disease.

We aimed to determine the prevalence of radiological temporal bone features that in previous studies showed only a weak or an inconsistent association with the clinical diagnosis of Meniere's disease (MD), in two groups of MD patients (n = 71) with previously established distinct endolymphatic sac pathologies; i.e. the group MD-dg (ES degeneration) and the group MD-hp (ES hypoplasia). Delayed gadolinium-enhanced MRI and high-resolution CT data were used to determine and compare between and within (affected vs. non-affected side) groups geometric temporal bone features (lengths, widths, contours), air cell tract volume, height of the jugular bulb, sigmoid sinus width, and MRI signal intensity alterations of the ES. Temporal bone features with significant intergroup differences were the retrolabyrinthine bone thickness (1.04 ± 0.69 mm, MD-hp; 3.1 ± 1.9 mm, MD-dg; p < 0.0001); posterior contour tortuosity (mean arch-to-chord ratio 1.019 ± 0.013, MD-hp; 1.096 ± 0.038, MD-dg; p < 0.0001); and the pneumatized volume (1.37 [0.86] cm3, MD-hp; 5.25 [3.45] cm3, MD-dg; p = 0.03). Features with differences between the affected and non-affected sides within the MD-dg group were the sigmoid sinus width (6.5 ± 1.7 mm, affected; 7.6 ± 2.1 mm, non-affected; p = 0.04) and the MRI signal intensity of the endolymphatic sac (median signal intensity, affected vs. unaffected side, 0.59 [IQR 0.31-0.89]). Radiological temporal bone features known to be only weakly or inconsistently associated with the clinical diagnosis MD, are highly prevalent in either of two MD patient groups. These results support the existence of diverse-developmental and degenerative-disease etiologies manifesting with distinct radiological temporal bone abnormalities.

Endolymphatic sac tumour - a rare complication associated with von Hippel-Lindau disease.

We report the case of a 42-year - old female with familiar form von Hippel-Lindau disease (VHL) and recurrent endolymphatic sac tumour (ELST), which was presented like non-homogenous, solid and cystic expansion of the left petrous temporal bone. Histologically, there was found lamellae of bone with adjacent ligament and with papillary projections with fibrovascular core. The papillae were lined by a single layer of cuboidal epithelium with hyperchromatic and lightly pleomorphic nuclei. Sporadically, small cystic formations with eosinophilic, PAS positive secretion were noted. Imunohistochemically, the cuboidal cells showed diffuse positivity for vimentin, epithelial membrane antigen (EMA), cytokeratin AE1/AE3 and S100 protein (weakly). Other markers examined, including TTF1, PAX8 and CD10, were negative. Endolymphatic sac tumour is rare low-grade malignant epithelial tumour arising from the endolymphatic sac in the temporal bone, which occurs in 1 out of 30 000 births, with just fewer than 300 cases reported in the literature. About one third of cases are associated with von Hippel- Lindau disease, an autosomal dominant familial cancer syndrome.

The Diagnosis and Management of Advanced Endolymphatic Sac Tumor.

Endolymphatic sac tumor (ELST) is a group of low-grade malignant tumors originating from the endolymphatic sac of the inner ear. It is rare in the clinic and has the biological characteristics of slow growth and local aggression. Due to the lack of specificity in the clinical manifestations of patients with ELST, many cases have entered the advanced stage at the time of diagnosis. However, there are still great challenges in the treatment of advanced ELSTs. Here, the authors describe a case of advanced ELST, which relapsed after 2 operations. This time, the authors chose the transotic approach for tumor resection, which achieved the goal of complete resection of the tumor, and the patient recovered smoothly after surgery. There were no surgical complications and no tumor recurrence after the follow-up. Through literature review and our own experience, the authors suggest that complete surgical resection is the first choice for both primary and recurrent advanced ELSTs. The choice of a reasonable surgical approach is the key to ensuring complete resection of the tumor, while preoperative angiography and embolization, fine treatment of important structures during surgery, and postoperative long-term follow-up are equally important for patients with advanced ELST to obtain a good prognosis.

Untargeted Metabolomic Analysis in Endolymphatic Sac Luminal Fluid from Patients with Meniere's Disease.

Dysfunction of the endolymphatic sac (ES) is one of the etiologies of Meniere's disease (MD), the mechanism of which remains unclear. The aim of the present study was to explore the molecular pathological characteristics of ES during the development of MD. Metabolomic profiling of ES luminal fluid from patients with MD and patients with acoustic neuroma (AN) was performed. Diluted ES luminal fluid (ELF) samples were obtained from 10 patients who underwent endolymphatic duct blockage for the treatment of intractable MD and from 6 patients who underwent translabyrinthine surgery for AN. ELF analysis was performed using liquid chromatography-mass spectrometry before the raw data were normalized and subjected to subsequent statistical analysis by MetaboAnalyst. Using thresholds of P ≤ 0.05 and variable important in projection > 1, a total of 111 differential metabolites were screened in the ELF, including 52 metabolites in negative mode and 59 in positive mode. Furthermore, 15 differentially altered metabolites corresponding to 15 compound names were identified using a Student's t-test, including 7 significant increased metabolites and 8 significant decreased metabolites. Moreover, two differentially altered metabolites, hyaluronic acid (HA) and 4-hydroxynonenal (4-HNE), were validated to be upregulated in the epithelial lining of the ES, as well as in the subepithelial connective-tissue in patients with MD comparing with that in patients with AN. Among these differentially altered metabolites, an upregulated expression of HA detected in the ES lumen of the patients with MD was supposed to be associated with the increased endolymph in ES, while an increased level of 4-HNE found in the ELF of the patients with MD provided direct evidence to support that oxidative damage and inflammatory lesions underlie the mechanism of MD. Furthermore, citrate and ethylenediaminetetraacetic acid were detected to be decreased substantially in the ELF of the patients with MD, suggesting the elevated endolymphatic Ca2+ in the ears with chronic endolymphatic hydrops is likely to be associated with the reduction of these two chelators of Ca2+ in ES. The results in the present study indicate metabolomic analysis in the ELF of the patients with MD can potentially improve our understanding on the molecular pathophysiological mechanism in the ES during the development of MD.

Surgical management of endolymphatic sac tumor: classification, outcomes and strategy. A single institution's experience.

PURPOSE: To review the resections of endolymphatic sac tumor (ELST) and describe our experience in the surgical management of ELST. METHODS: Retrospective investigation of consecutive patients who underwent resection of ELSTs at our hospital between 1999 and 2019. The symptoms, diagnosis, surgical findings, and outcomes were analyzed to develop a tumor staging system and corresponding surgical strategy. RESULTS: Retrospective review revealed the surgical treatment of 22 ELSTs. Based on intraoperative findings of tumor extent and size, ELSTs were classified into two types. Type-I (n = 6) referred to the small tumors that were locally confined with limited invasion of semicircular canals and dura; type-II (n = 16) referred to the large tumors that presented extensive erosion of at least one anatomic structure apart from the semicircular canals and the dura around endolymphatic sac. In this case series, Type-I ELST is amenable to resection through a transmastoidal approach, and subtotal petrosectomy is appropriate for the resection of type-II ELST. Sensorineural hearing loss (SNHL) is the most commonly preoperative symptom in both two types of cases. Five type-II ELSTs experienced recurrence and underwent reoperation, whereas all type-I ELSTs did not. CONCLUSION: ELST usually results in SNHL (95%) at the time of diagnosis. The surgical strategy and prognosis of ELST resections are different between type-I and type-II: type-I ELST is amenable to transmastoidal approach with the preservation of facial nerve, whereas type-II ELST increase the surgical difficulty and the risk of recurrence, and subtotal petrosectomy is the basic requirement for the resection of type-II ELST.

Meniere's Disease Patients with Distinct Sac Pathoanatomic Findings React Differently to Endolymphatic Duct Blockage.

OBJECTIVES: To explore the possible difference in response to endolymphatic duct blockage (EDB) treatment in patients with Meniere's disease (MD) with distinct pathoanatomic characteristics of the sac. METHODS: In a total of 24 patients with MD receiving EDB treatment, the dynamics of the vertigo attack, hearing, vestibular function, and endolymph hydrops (EH) before surgery and 40 months following surgery in patients with normoplastic extraosseous portion of endolymphatic sac (eES) were compared with that in patients with atrophic eES. RESULTS: A higher prevalence of complete vertigo control, better cochlear and vestibular function, and lower endolymph to vestibule-volume ratio were found in patients with normoplastic eES than in those with atrophic eES. Moreover, the reversal of EH was found in a total of six patients in normoplastic eES group, but no reversal of EH was detected in the atrophic eES group after surgery. CONCLUSIONS: A difference in response to EDB treatment was shown in the MD patients with normoplastic eES and those with atrophic eES; the reversal of EH was found in the normoplastic eES group, but not in the atrophic eES group after surgery, suggesting two distinct pathologies in the eESs may underlie the pathogenesis of EH in two subgroups of MD patients. LEVEL OF EVIDENCE: 4 Laryngoscope, 133:2761-2769, 2023.

Endolymphatic sac tumor in an 8-month-old cat.

Background: The endolymphatic sac is an organ devoid of sensory receptors. It is connected with the endolymphatic compartment and contains endolymph. Endolymphatic sac tumor (ELST) is a rare neoplasm involving the middle and inner ear described in humans and dogs that does not show cellular characteristics of malignancy, but can be locally invasive and involve destruction of the temporal bone and adjacent structures. Case Description: An 8-month-old female cat was referred because of sudden onset of vestibular signs starting 3 days prior to referral. On clinical examination, the patient showed depression, right head tilt, left-sided facial paralysis, and horizontal nystagmus with fast phase to the left. The magnetic resonance images showed a voluminous extra-axial lesion, with irregular morphology and well-defined margins, with intracranial extension in the region of the pons, rostral medulla oblongata, cerebellar vermis, floccule, and left cerebellar hemisphere. Due to progressive clinical deterioration, the cat was euthanized 2 weeks later. A necropsy was then performed and histological samples were taken. The necropsy revealed the presence of a voluminous dark red irregular mass extending from the tympanic bulla to the posterior cranial fossa following the left glossopharyngeal nerve. The histopathological exam of the extra-axial lesion featured a nonencapsulated, moderately cellular, rather loose, proliferation of cuboidal to columnar epithelium breaching through chunks of an otherwise normal appearing dura mater and invading some cranial nerves. Sections of the cerebellum and brainstem revealed moderate, focal, impingement of the parenchyma with a very mild extension of the proliferating cells into the ventral left side of the medulla oblongata. Based on these histological characteristics, the lesion was defined as ELST, a rare neoplasm described in human beings and with two reports in dogs. Conclusion: To our knowledge, this is the first report describing an ELST in a cat.

Symptoms and clinical features in patients affected by endolymphatic sac tumor: a systematic review and meta-analysis.

PURPOSE: Most ELST data in the literature are case studies or limited to small cohorts (< 16 patients). We evaluated the main clinical signs observed at endolymphatic sac tumor (ELST) diagnosis in patients with or without Von Hippel-Lindau disease. METHODS: We conducted a comprehensive literature search in PubMed, Scopus, and Web of Science. We included studies with at least 1 patient, of any age, affected by sporadic or VHL-related ELSTs reporting levels of hearing loss and facial nerve function and a comprehensive description of presenting symptoms at ELST diagnosis. We combined data for proportional meta-analysis. p values of 0.05 were considered statistically significant. Methodological quality was evaluated. Analyses were performed with MedCalc 14.8.1 software. RESULTS: A total of 26 studies, including 113 patients and 118 cases of ELSTs were included. Pooled proportion rates (95% CI) of overall hearing loss was 88.7%, (82.4-93.4), severe hearing loss was 21.6% (12.8-32.1) profound hearing loss was 39.8% (28.7-51.5), vertigo/imbalance was 42.0% (33.8-50.5), tinnitus was 61.8% (53.4-69.8) and facial nerve palsy was 30.6% (23.2-38.9). Generally, symptoms were homogeneous or moderately heterogeneous among included studies. CONCLUSION: This is the first systematic review of clinical presentations at ELST diagnosis. The most serious clinical events include profound hearing loss and facial impairment. Fluctuating hearing loss, tinnitus and vertigo are frequently reported and may confound correct and prompt ELST diagnosis.

Cytological features of endolymphatic sac tumors: Case studies with review of literature.

Endolymphatic sac tumors are extremely rare, locally aggressive neoplasms that arise from the endolymphatic sac or duct, primarily in the intraosseous portion. These neoplasms show diverse histomorphological architectures and despite a bland cytologic appearance, can locally recur. Although the clinicopathological and radiological features of this entity are well characterized, the literature on cytological features is extremely sparse. Herein, we describe the cytological features of the endolymphatic sac tumors and discuss the relevant differential diagnoses.

Endolymphatic Sac Tumor as a Ménière-Like Vertiginous Syndrome: A Case Report.

Endolymphatic sac tumors are rare benign neoplasms with locally aggressive behavior located in the posterior petrous ridge of the temporal bone. They cause sensorineural hearing loss and may develop vestibular damage. A 24-year-old male patient arrived at our office with a history of acute vertiginous syndrome, left hearing loss, and tinnitus 1-year ago. His chief complaint was an increase in auditory symptoms. A CT scan and MRI showed an endolymphatic sac tumor. Complete resection of the lesion was achieved by a transmastoid and translabyrinthine approach. Low-grade adenocarcinoma was confirmed by histopathology. The patient remained without clinical vestibular symptoms. However, a small residual tumor was addressed by gamma-ray radiosurgery. Postoperative deep left sensorineural hearing loss was identified, without any vestibular sequelae. Radiologic imaging is the most useful tool for this diagnosis. Endolymphatic sac tumors should be in the differential diagnosis of recalcitrant audio-vestibular symptoms. Complete surgical resection is the most appropriate management.

Endolymphatic sac tumor: single-institution series of seven cases with updated review of literature.

BACKGROUND: Endolymphatic sac tumour (ELST) is a rare low-grade locally aggressive neoplasm arising from the endolymphatic duct or sac. It presents mostly with vestibulo-cochlear symptoms either sporadically or as part of von Hippel-Lindau (VHL) syndrome. Micro-neurosurgical excision remains the cornerstone of therapy with the role of radiotherapy (RT) being controversial. This is a clinico-pathological analysis of consecutive ELST patients presenting to a single-institution in India. METHODS: Neuropathology database of a tertiary-care comprehensive cancer centre was searched electronically to identify consecutive patients with histopathological diagnosis of ELST registered at the institute over last one decade. Data regarding demographic profile, clinical presentation, histopathological features, treatment details and outcomes were retrieved from electronic medical records for this retrospective analysis. RESULTS: Electronic search identified seven unique patients with biopsy-proven ELST registered at the institute between 2009 and 2020. Median age of the study cohort was 39 years (range 24-65 years) with strong male predilection (5:2 ratio) and left-sided preponderance (71%). Most common presenting symptoms were hearing loss (86%) and earache (71%) on affected side followed by headache (43%). All patients underwent maximal safe resection at initial diagnosis and were followed-up closely with periodic surveillance imaging. Two patients underwent salvage RT using high-precision conformal techniques at recurrence/progression. CONCLUSION: ELST is a rare low-grade locally aggressive neoplasm that arises generally as part of VHL syndrome or sometimes sporadically. Gross total resection provides the best chance of cure with RT being reserved for unresectable disease, large residue, medical inoperability, or as salvage therapy for recurrent/progressive tumor.

Endolymphatic Sac Tumour: A Case Report and Review of the Literature

Introduction Endolymphatic sac tumor (ELST) is a slow-growing, low-grade, locallyinfiltrative tumor arising from the endolymphatic sac/duct, which is located in the posterior part of the petrous temporal bone. It may be sporadic in origin, or may be associated with Von-Hippel Lindau (VHL) syndrome. Case description A 40-year-old female patient with an ELST without VHL syndrome who was treated successfully by microsurgical extirpation of the tumor. Discussion We discuss the radiological features and the histopathology of this rare tumor and review the relevant literature. Conclusion The case herein reported adds to the previously-reported cases of this rare tumor.

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.

Long experience for the diagnosis and treatment of sporadic endolymphatic sac tumor in a single center.

OBJECTIVES: Sporadic endolymphatic sac tumor (ELST) is rare. The purpose of this study was to analyze the clinical feature and surgical outcome of a single-center series of sporadic ELSTs. PATIENTS AND METHODS: We retrospectively reviewed all cases of sporadic ELSTs operated at the Tiantan hospital between 2010 and 2020. RESULTS: Retrospective record revealed 14 patients with sporadic ELSTs who underwent surgical management. Serum VEGF(vascular endothelial growth factor)values of 6 patients were measured on admission, and the levels were all higher than normal(0-160 ng/L, Enzyme-Linked ImmunoSorbent Assay). All patients underwent surgical treatments, and there was no significant difference in KPS before and after the operation(KPS = 88:88). The average maximum diameter of the tumor was 41 mm (range28-56 mm). After surgery, Two patients received radiation therapy, We did not encounter any case with metastatic dissemination. No deaths occurred during follow-up. CONCLUSION: ELST is defined as an aggressive or low-grade malignant tumor, with the characteristics of local recurrence and invasion of bone growth. Sporadic cases are common, and this rare tumor provides insight into the relationship between ELST and VHL syndrome. Early surgical resection can prevent or reduce the disability of auditory vestibular symptoms, and improve the chance of complete resection and retention of hearing. As far as possible complete resection of the tumor can prolong the disease-free survival of patients. Preoperative radiotherapy or stereotactic therapy cannot control tumor growth. Postoperative radiotherapy may have a positive effect on tumor control. The high expression of VEGF in patients may be related to tumor occurrence and development.

68Ga-DOTATATE Uptake in an Endolymphatic Sac Tumor: Radiologic-Pathologic Correlation.

After dedicated CT and MRI, Ga-DOTATATE PET/CT was performed in a patient with a temporal bone mass with primary diagnostic considerations of an endolymphatic sac tumor versus a glomus jugulotympanicum paraganglioma. The Ga-DOTATATE PET showed mild radiotracer uptake in the mass (SUVmax, 10.9). After surgical resection, pathology revealed an endolymphatic sac tumor. Immunohistochemical staining demonstrated somatostatin receptor type 2A expression in the vasculature of the mass, but not in the tumor cells.