Current Treatment of Endolymphatic Sac Tumor of the Temporal Bone

Evaluation of Tumor-Infiltrating Leukocytes in Endolymphatic Sac Tumor

OBJECTIVE

Endolymphatic sac tumors (ELSTs), as rare low-grade neoplasms, are primarily treated with surgery. This study analyzes the characteristics of tumor-infiltrating leukocytes (TILs) in ELSTs and their relationships with clinical features to explore the potential for immunotherapy in ELSTs.

METHODS

Clinical data and tumor specimens of 10 ELSTs patients who underwent surgery were retrieved. Immune expression levels of CD3, CD4, CD8, and CD66b were assessed by immunohistochemical staining and expressed as the integral optical density (IOD). Hematoxylin and eosin (HE) staining were performed to define the tumor nest and stroma of ELSTs.

RESULTS

There were no significant differences in the IOD of CD3, CD4, CD8, and CD66b between the tumor nest and stroma or between von Hippel-Lindau (VHL) and non-VHL patients. The IOD of CD3, CD4, CD8, and CD66b appeared relatively higher in patients with endolymphatic hydrops (EH) than those without. Additionally, CD4 expression in the tumor stroma was significantly higher in patients with EH (p = 0.0381).

CONCLUSION

TILs were present in both ELSTs nest and stroma with significant individual heterogeneity observed among patients. Patients with VHL disease showed a similar immune pattern to those with sporadic ELSTs. Notably, the ELST-related EH may be associated with lymphocytes infiltration. Combined with surgical intervention, immunotherapy may serve as an effective adjuvant therapeutic strategy.

LEVEL OF EVIDENCE

4 Laryngoscope, 135:2128-2133, 2025.

Surgical Management and Prognostic Factors for Endolymphatic Sac Tumor: A Single-Institute Experience with a Systematic Review

OBJECTIVE

To evaluate the clinical features, surgical outcomes, and predictors of progression-free survival (PFS) in patients with endolymphatic sac tumors (ELSTs).

METHODS

This retrospective study analyzed 15 cases from Beijing Tiantan Hospital and 237 from the literature (1988-2023), focusing on patients with pathologically confirmed intracranial or skull ELSTs who had comprehensive treatment and follow-up records. Univariate and multivariate Cox regression analyses were used to identify factors influencing PFS.

RESULTS

Patients from our institute comprised 10 males and 5 females, with an average age of 39.1 years. Among these patients, 86.7% underwent gross total resection (GTR). During the follow-up period, 2 patients (13.3%) were lost to follow-up. After a mean follow-up of 74.9 months, 1 patient experienced recurrence and another died from unrelated causes. A review of the literature identified 237 additional patients, including 134 females (56.5%), with an average age of 39.8 years; 22.8% of these patients had von Hippel-Lindau disease. The GTR rate was 69.2%. After a mean follow-up of 53.2 months, 33 recurrences occurred, and the median PFS was 48 months. In addition, 8 patients died during the follow-up period; none of the deaths was attributed to ELSTs. Multivariate analysis identified GTR (hazard ratio, 0.279; 95% confidence interval, 0.086-0.903; P = 0.033) as a significant protective factor against recurrence among the pooled cases.

CONCLUSIONS

GTR is crucial for improving PFS in patients with ELST, emphasizing the need for advanced surgical techniques and long-term follow-up because of potential recurrences.

Surgical Outcomes in Patients with Endolymphatic Sac Tumors: A Single-Center Experience of 29 Patients

OBJECTIVE

To analyze the clinical features and surgical outcomes of patients with endolymphatic sac tumors (ELSTs).

STUDY DESIGN

Single institution retrospective cohort study.

METHODS

The clinical data of 29 patients with 30 ELSTs who underwent surgery were retrospectively reviewed. Information on patient demographics, tumor size and grade, intraoperative blood loss volume, hearing and facial nerve outcomes, and follow-up data was collected and analyzed.

RESULTS

The main symptoms were hearing loss in 26 ELSTs (86.7%) and tinnitus in 17 (56.7%). Twenty-four (80%) ELSTs were in advanced stages (Grade III). The median tumor volume was 6.35 cm3. The median intraoperative blood loss volume was 300 mL. Facial nerve function was well preserved in 21 patients. Among all patients with Grade III tumors, 12 patients underwent tension-free anterior facial nerve rerouting, and 11 patients (91.7%) maintained good facial nerve function postoperatively (HB I and HB II). Only one patient exhibited permanent vocal cord paralysis, and no patients experienced cerebrospinal fluid (CSF) leakage postoperatively. Gross total resection was achieved in 22 patients (73.3%), 5 patients (16.7%) experienced tumor recurrence, and 3 (10%) had residual tumors.

CONCLUSIONS

Most ELSTs tend to be diagnosed in the advanced stage. Tension-free anterior facial nerve rerouting could maximally preserve facial nerve function. The intraoperative blood loss volume was associated with tumor size and stage. Tumor recurrence tends to occur at the posterior edge of the petrosal bone, internal auditory canal, and surface of the posterior fossa. Given the relatively high recurrence rate of ELSTs, long-term follow-up is recommended.

LEVEL OF EVIDENCE

4 Laryngoscope, 135:339-344, 2025.

Case report: Cochlear implantation for deafness caused by endolymphatic sac tumors in patients with von Hippel-Lindau syndrome

Introduction

Endolymphatic sac tumors (ELSTs) are rare neuroectodermal neoplasms that originate in the endolymphatic sac and duct. They exhibit no specific age or gender predilection, although they are more prevalent in patients with von Hippel-Lindau syndrome.

Material and methods

The manuscript preparation adhered to the CARE guidelines for standardizing clinical cases and the PRISMA guidelines for scientific reviews. Three studies that met the inclusion criteria were selected from an analysis of 15 articles, supplemented by two additional studies identified through citation review.

Results

The presented case describes a 16-year-old boy diagnosed with unilateral sensorineural hearing loss secondary to bilateral ELST. Surgical excision of the right ear tumor with simultaneous cochlear implantation was performed, followed by left ear surgery. Hearing restoration was achieved in the implanted right ear, with normal hearing in the left ear, and no postoperative vestibular symptoms were observed.

Conclusion

Prompt surgical intervention remains the cornerstone of ELST treatment. While cochlear implantation is sporadically reported in scientific literature, it offers a potential option for hearing improvement in patients suffering from deafness caused by the disease.

Endolymphatic sac tumor: An urgent case presenting acute intracranial hypertension successfully treated with suboccipital decompressive craniectomy - 8 years of follow-up

Background

Endolymphatic sac tumor (ELST) is a rare lesion. It may be sporadically or associated with Von Hippel-Lindau syndrome. Progressive audiovestibular symptoms characterize the typical clinical presentation. Here, we report a unique case of ELST with acute intracranial hypertension (IH) due to tumor compression, successfully treated with an urgent suboccipital decompressive craniectomy (SDC).

Case Description

A 33-year-old woman previously underwent a biopsy and ventriculoperitoneal shunt. The histopathological finding revealed an ELST. One year later, she developed headache, vomiting, and somnolence due to brainstem compression. An urgent SDC was performed. One month later, preoperative endovascular embolization and partial tumor resection were carried out. After 6 months adjuvant radiotherapy (RT) therapy was administered. She has been under follow-up for 8 years since the last surgical procedure, and the tumor remains stable.

Conclusion

ELST generally has a progressive clinical course. This is a unique case with acute IH due to tumor compression. The tumor's high vascularity and the unavailability of endovascular embolization precluded its resection. SDC was an alternative approach. The final treatment included tumor embolization, surgical resection, and RT. No progression was observed for 8 years after the last procedure, and long-term follow-up is warranted.

Fluid-solid coupling model and biological features of large vestibular aqueduct syndrome

Objective: Computed tomography (CT) images of the temporal bone of large vestibular aqueduct syndrome (LVAS) patients were used to establish 3D numerical models based on the structure of the inner ear, which are, in turn, used to construct inner ear fluid-solid coupling models. The physiological features and pathophysiology of LVAS were analyzed from a biomechanical perspective using finite element analysis. Methods: CT images of the temporal bone were collected from five children attending the Second Hospital of Dalian Medical University in 2022. The CT images were used to build 3D models of the inner ear containing the vestibular aqueduct (VA) by Mimics and Geomagic software, and round window membrane models and fluid-solid coupling models were built by ANSYS software to perform fluid-solid coupling analysis. Results: By applying different pressure loads, the deformation of the round window membranes occurred, and their trend was basically the same as that of the load. The deformation and stress of the round window membranes increased with the increase in load. Under the same load, the deformation and stress of the round window membranes increased with the expansion of the midpoint width of the VA. Conclusion: CT images of the temporal bone used clinically could establish a complete 3D numerical model of the inner ear containing VA. Fluctuations in cerebrospinal fluid pressure could affect inner ear pressure, and VA had a limiting effect on the pressure from cerebrospinal fluid. The larger the VA, the smaller the limiting effect on the pressure.

Systematic Review of Endolymphatic Sac Tumor Treatment and Outcomes

OBJECTIVE

Endolymphatic sac tumors are rare neoplasms originating in the endolymphatic sac. Current literature is limited to case reports and small case series. The objective of this study was to systematically review the literature to better describe clinical presentation, treatment options, and outcomes in endolymphatic sac tumors.

DATA SOURCE

PubMed, Embase, and Cochrane Library.

REVIEW METHODS

A systematic review was performed following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines describing human endolymphatic sac tumors. Risk of bias was assessed using a validated critical appraisal checklist for case series. Studies without inclusion of individual patient characteristics, corresponding treatments, and outcomes were excluded. Heterogeneity of data precluded meta-analysis.

RESULTS

A total of 82 studies met inclusion criteria, and 253 discrete tumors were analyzed. A total of 23.4% of patients had von Hippel-Lindau disease. Von Hippel-Lindau-associated tumors affected females to males in a 2.4:1 ratio. Patients with von Hippel-Lindau disease displayed earlier average age at diagnosis compared to the sporadic cohort. Surgery was the primary treatment modality and was performed in 88.9% of cases. Adjuvant radiation therapy was employed in 18.7% of cases; 16.2% cases recurred, and 10.6% had progression of residual disease after treatment. Mean time to recurrence or progression was 53.1 ± 52.4 months with a range of 3 to 240 months.

CONCLUSION

Endolymphatic sac tumors require a high degree of suspicion for early diagnosis. Complete resection is the standard of care. No strong evidence supports routine use of adjuvant radiation therapy. Given the high rate of recurrence and wide-ranging time to recurrence, long-term follow-up is necessary.

Sinus tympani revisited for planning retrofacial approach-radiologic study in pneumatized temporal bones and its surgical implications

BACKGROUND AND PURPOSE

Retrofacial approach (RFA) is an access route to sinus tympani (ST) and it is used in cholesteatoma surgery, especially when type C ST is encountered. It may also be used to gain an access to stapedius muscle to assess the evoked stapedius reflex threshold. The primary object of this study was to evaluate the morphology of sinus tympani and its relationship to facial nerve (FN) and posterior semicircular canal (PSC) in context of planning retrofacial approach in pneumatized temporal bones.

METHODS

CBCT of 130 adults were reviewed. The type of sinus tympani was assessed according to Marchioni's classification. Width of entrance to sinus tympani (STW), depth of ST (STD), distance between the posterior semicircular canal and facial nerve (F-PSC), distance between the latter plane to the floor of ST at the right angle (P-ST) were measured at level of round window (RW) and pyramidal ridge (PR).

RESULTS

All of the bones were well-aerated and classified in Dexian Tan pneumatization group 3 or 4. Type B of ST is dominant (70.8%) in adult population with no history of inflammatory otologic diseases, followed by type C (22.7%) and then type A (6.5%). The depth of ST (STD) presented significant deviations (ANOVA, p < 0.05) among all three types. STW reaches greater values on the level of PR. F-PSC does not correlate with type of ST. In over 75% of examined type C sinus tympani the distance P-ST was less than 1 mm.

CONCLUSIONS

The qualitative classification of the sinus tympani into types A, B and C, introduced by Marchioni is justified by statistically significant differences of depth between individual types of tympanic sinuses. The STW distance reaches greater values inferiorly-it may suggest that RFA should be performed in infero-superior manner rather than opposite direction. Preoperative assessment of temporal bones CT scans gives very important information about size of sinus tympani and distance between FN and PSC.

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.

Abdominal Pain and Examination of Hernial Orifices: The Forgotten Art of Physical Diagnosis

Introduction: Acute abdominal pain can be the first manifestation of a hernial pathology. The estimated risk of incarcerated hernia is 1%-3% over a person's lifetime. Therefore, hernial orifice examination should be conducted routinely, especially in cases of abdominal pain. We hypothesized that physical examination of hernial orifices is not routinely performed and documented in patients presenting with acute abdominal pain.

Methods: A retrospective chart review of 100 patients who were evaluated for abdominal pain over a three-month time frame at our institution.

Results: From the 100 reviewed cases, the hernial orifice examination was performed in two cases by an Internal Medicine or Emergency Medicine physician (2%). Out of the eight cases with General Surgery consultation, only one case had hernial orifices examination (12.5%). In the 10 cases with Gastroenterology consultation, not a single case had hernial orifice examination.

Conclusion: We demonstrate that hernial examination is infrequently performed in clinical practice and suggest that emphasis should be placed on the efficient performance of physical examination and maintain the art of physical diagnosis.

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.

Papillary Mucinous Adenocarcinoma of the Endolymphatic Sac: A Rare Middle Ear Neoplasm

Glandular neoplasms of the temporal-mastoid region and endolymphatic sac (ELS) are rare, and it is quite challenging to differentiate between an adenoma and an adenocarcinoma. ELS tumors (ELST) usually present with papillary, follicular, or solid patterns and can be further distinguished histologically and through immunohistochemistry. The microscopic features and clinical course of this neoplasm have been comprehensively explained by Heffner, who considered it "low-grade adenocarcinoma of likely ELS origin." The papillary form more commonly affects females, and it is a more aggressive form of ELST that is destructive and exhibits extensive local spread. The tumor usually has a close association with von Hippel-Lindau (VHL) disease, but 11%-30% of the ELST cases develop in individuals without a VHL mutation. ELSTs manifest with headaches, hearing loss, ear discharge, and cranial nerve palsies. Currently, the only available curative therapeutic intervention consists of wide local excision and long-term follow-up. Because of the sensitive location of this tumor, the adjuvant radiotherapy options are still questionable. In this case report, the author presents a 74-year-old woman with a past medical history of Schneiderian papilloma and was diagnosed with papillary mucinous adenocarcinoma of the ELS not associated with VHL disease.

Posterior Skull Base Anatomy and Pathology

A posterior skull base lesion is an uncommon radiological finding that may be noted incidentally or during targeted imaging of patients with clinical symptoms attributable to the lesion. It may be inflammatory or neoplastic in etiology, or may simply be an anatomic variant or a "don't-touch" lesion that should not be misinterpreted as something more ominous. A systematic approach to the evaluation of the posterior skull base is therefore required in order to differentiate lesions requiring immediate attention from those requiring a less urgent course of action or none at all. This review will focus on the imaging features of pathologic conditions that are more commonly encountered in posterior skull base CT and MR examinations.

The biomechanical characteristics of human vestibular aqueduct: a numerical-based model construction and simulation

Vestibular aqueduct is a precise structure embedded in the temporal bone and plays a key role in the physiological function of inner ear by maintaining the endolymphatic circulation and buffering the impact from intracranial pressure. Although the alterations on the morphology or volume of vestibular aqueduct result in variety of diseases, the approaches of evaluating the condition of vestibular aqueduct are still unsatisfing because the pathological sections utilized for the 3D construction model most likely undergoes morphological changes. In this study, the vestibular aqueduct images obtained by CT scanning were processed by finite element method to construct the 3D model. To assess if this numerical model reflects the actual biomechanical properties of vestibular aqueduct, the fluid-solid coupling calculation was applied to simulate the endolymphatic flow in the vestibular aqueduct. By measuring the dynamics of endolymphatic flow, and the pressure and displacement on round membrane under external pressure, we found the numerical 3D model recapitulated the biomechanical characteristics of the real vestibular aqueduct. In summary, our approach of 3D model construction for vestibular aqueduct will provide a powerful method for the research of vestibular aqueduct-related diseases.

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.

The endolymphatic sac tumor: challenges in the eradication of a localized disease

OBJECTIVE

Identify the critical points that lead to recurrences and lack of radicality in endolymphatic sac tumors (ELSTs).

STUDY DESIGN

Retrospective case study and review of the literature.

SETTING

Tertiary referral center.

PATIENTS

Thirteen cases of ELST were included in the study and their preoperative, intraoperative and postoperative data were analyzed and compared to a review of the literature.

INTERVENTION(S)

Therapeutical.

MAIN OUTCOME MEASURE(S)

Prevalence of recurrent and residual tumors, comparison to the literature and analysis of ELST characteristics.

RESULTS

Diagnosis was made 26 ± 17 months after the onset of symptomatology, and an ELST was preoperatively suspected in only six cases. At the time of surgery, 10 patients suffered from hearing loss. Preoperative symptoms or audiometry could not predict labyrinth infiltration, although speech discrimination scores were significantly associated with labyrinth infiltration (p = 0.0413). The labyrinth was infiltrated in 8 cases (57.1%), and in 7 cases (46.7%) the tumor eroded the carotid canal, whereas 6 cases (40%) presented an intradural extension. A gross total resection was achieved in 11 cases. There were two residual tumors, one of which because of profuse bleeding, and one recurrence (23.1%). A mean of 22.8% of recurrent or residual tumors are described in the literature based on 242 published cases, in more than half of the cases as a consequence of subtotal tumor resection (STR).

CONCLUSIONS

Recurrence derives mostly from the difficulty to identify the extension of the tumor due to the extensive bone infiltration. Accurate diagnosis and correct preoperative planning, with embolization when possible, will facilitate surgery and avoid STR due to intraoperative bleeding. Long follow-ups are important in order to avoid insidious recurrences.

Clinical features and treatment of endolymphatic sac tumor

Background: Endolymphatic sac tumor (ELST) is an extremely rare disease that does not have established clinical guidelines.Objective: To provide guidance for the diagnosis and management of ELSTs.Methods: We retrospectively reviewed the medical records of patients who were suspected to have a lesion in the location of endolymphatic sac. Seven patients were included. Histopathologic diagnosis confirmed five ELSTs and two other diseases.Results: All of the enrolled patients had hearing impairment. Facial palsy was found in four out of five patients with ELST, whereas none of the patients in other disease group showed facial palsy. CT and MRI findings were consistent with those in previous literatures; however, angiographic findings were not consistent with those previously reported. All patients underwent surgery. Recurrence occurred in two patients with ELST, although there was no visible remnant tumor after the operation. These patients were treated with stereotactic radiosurgery.Conclusion: Hearing impairment and facial palsy were representative symptoms of ELST. All ELSTs showed 'salt and pepper' signal in MRI T1-weighted images, and smaller tumors could have blood supply from AICA in the radiologic study. Complete surgical resection with optional stereotactic radiosurgery should be considered in ELST.HighlightsHearing impairment and facial weakness are remarkable symptoms of ELST compared to other diseases that invade the endolymphatic sac.All ELSTs showed 'salt and pepper' signal in MRI T1-weighted images.ELST less than 3 cm in diameter could have blood supply from AICA.A complete surgical excision with optional stereotactic radiosurgery is required.

Fibrous dysplasia mimicking a pediatric endolymphatic sac tumor

A 15-year-old female presented for evaluation of progressive hearing loss over a year. Computed tomographic imaging revealed a 11 x 6 × 6 mm osseous lesion with 'groundglass' appearance within the left posterior petrous bone lateral to vestibular aqueduct suspicious for an endolymphatic sac tumor. Surgical excision revealed fibrous dysplasia on histological analysis. Fibrous dysplasia of the temporal bone is not uncommon, but few cases of extension causing sensorineural hearing loss exist in the literature. We describe the first reported case of fibrous dysplasia mimicking an endolymphatic sac tumor; interestingly, the patient also showed hearing improvement immediately following removal.

Transcanal endoscopic assisted skull base endolymphatic sac tumor resection: A rare disease with advanced technology

Endolymphatic sac tumors (ELSTs) are rare, papillary adenomatous tumors that arise from the endothelium of the endolymphatic sac. We demonstrate a difficult case of endolymphatic sac tumor and how it is managed via transcanal endoscopic assisted technique, with discussion of feasibility of transcanal approach to lateral skull base tumor.