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Table of Contents    
Year : 2011  |  Volume : 59  |  Issue : 4  |  Page : 608-611

Gamma knife treatment of an endolymphatic sac tumor: Unique features of a case and review of the literature

Department of Neurosurgery of the West China Hospital, Sichuan University, Chengdu, Sichuan Province, China

Date of Submission14-Nov-2010
Date of Decision07-Dec-2010
Date of Acceptance16-Jan-2011
Date of Web Publication30-Aug-2011

Correspondence Address:
Wei Wang
Department of Neurosurgery of the West China Hospital, Sichuan University, Guoxue Street 37, Chengdu, Sichuan Province 610041
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0028-3886.84348

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 » Abstract 

Endolymphatic sac tumors are rare, histologically non-aggressive lesions, but often become locally invasive and lead to erosion of the petrous bone. We report a rare case with multiple endolymphatic sac tumors located at bilateral cerebellopontine angles and vermis of the cerebellum. One of the lesions was surgically resected and others were treated using gamma knife radiosurgery. Local recurrence and metastasis occurred, which was treated with gamma knife radiosurgery. With an appropriate prescription dose and isodose, gamma knife radiosurgery may have an important role in the treatment of endolymphatic sac tumor.

Keywords: Cerebellopontine angle, endolymphatic sac tumor, gamma knife radiosurgery

How to cite this article:
Cheng X, Qin S, Wang X, Li P, Shrestha B, Wang W. Gamma knife treatment of an endolymphatic sac tumor: Unique features of a case and review of the literature. Neurol India 2011;59:608-11

How to cite this URL:
Cheng X, Qin S, Wang X, Li P, Shrestha B, Wang W. Gamma knife treatment of an endolymphatic sac tumor: Unique features of a case and review of the literature. Neurol India [serial online] 2011 [cited 2023 Dec 11];59:608-11. Available from:

 » Introduction Top

Endolymphatic sac tumor (ELST), first described in 1984, by Hassard et al., [1] is a rare, histologically non-aggressive lesion, but often becomes locally invasive and leads to erosion of the petrous bone. Most often ELST are solitary, bilateral lesions, mostly seen in patients with von Hippel-Lindau (VHL) disease and only 1% of the bilateral lesions occur in other patients. [2] We report a patient with multiple ELSTs treated with gamma knife radiotherapy, and review the relevant literature review.

 » Case Report Top

A 44-year-old male presented with progressive hearing loss on the left side, of two months' duration and left facial weakness and hypoacusis on the right side, since few weeks. A neurological examination revealed left side sensorineural deafness and moderate hearing loss on the right side, and also a left lower motor neuron type of facial palsy. Magnetic resonance imaging (MRI) revealed three homogeneously enhancing lesions located in both the cerebellopontine angles and the vermis of the cerebellum [Figure 1]. Diagnosis of metastatic disease was considered and a work-up was conducted for the primary focus: computed tomography (CT) scan of the chest and abdomen, serum tumor markers (CEA, SCC, CA-125, CA-19-9, CYFRA21-1, and T-PSA), colonoscopy, and 99mTc-methylene diphosphonate bone scanning, which were all normal.
Figure 1: Axial, coronary and sagittal T1-weighted postcontrast magnetic resonance (MR) images showed three masses as indicated by white arrows, two of them with the diameter about 0.5 cm located at bilateral CPAs (a,c) and the third nodule located in the vermis cerebelli (b,d)

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He was taken up for exploratory surgery. He underwent a left retromastoid suboccipital craniectomy. Intraoperatively the tumor was grayish-red, soft, and fragile (0.6 cm×0.2 cm×0.1 cm) and was close to the facial and vestibulocochlear nerves. The tumor was carefully isolated from the cranial nerves and radical resection of the lesion was done. The pathology of the tumor showed a papillary-glandular appearance, with soft tissue invasion and bony erosion. The lesion showed a clear cell predominance resembling prostate carcinoma and renal cell carcinoma. On immunohistochemical evaluation, the tumor was positive for epithelial membrane antigen (EMA), pan-cytokeratin (PCK), cytokeratin 7 (CK7), neuron specific endolase (NSE), and CDX 2. The tumor was negative for cytokeratin 20 (CK20), CD31, CD34, CD57, Nestin, D2-40, Vimentin (Vim), S100, glial fibrillary acid protein (GFAP), prostate specific antigen (PSA), and thyroid transcription factor-1 (TTF1) [Figure 2].
Figure 2: The microscopic architecture of lesions. (a) The tumor are composed of multiple papillary glands lined by a single layer of cuboidal-to-columnar cells and invasion of the bone. H and E, ×8. (b) The neoplastic cells demonstrate atypia. H and E, ×50. (c) The neoplastic cells demonstrate atypia. H and E, ×100. (d) The neoplastic cells demonstrate atypia and mitotic activity. H and E, ×200. (e) The tumor cells are positive for EMA. En Vision, ×100. (f) The tumor cells are positive for PCK. En Vision, ×100. (g) The tumor cells are positive for CK 7. En Vision, ×100. (h) The tumor cells are negative for Vim. En Vision, ×100

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As the patient refused a second surgery to resect the right side lesion, stereotactic radiosurgery, gamma knife radiosurgery was performed, two months after the first surgery, with a prescription dose of 17.0 Gy and a prescription isodose of 50.0% [Figure 3]a. A follow-up scan five months after surgery, showed metastases to the brainstem. Brainstem metastases were treated with gamma knife radiosurgery with a prescription dose of 11.0 Gy and a prescription isodose of 50.0% [Figure 3]b. After 18 months of the first surgery, the tumor in the right cerebellopontine angle regressed in size and the lesions in the vermis of cerebellum and brainstem disappeared. He had recurrence of a left-side tumor resulting in vertigo and cerebellar ataxia, and the recurrent tumor was treated with gamma knife radiosurgery with a prescription dose of 16.0 Gy and a prescription isodose of 50.0% [Figure 3]c. At a follow-up, 27 months after the first gamma knife radiosurgery, the tumor in the right cerebellopontine angle had recurred and the recurrent tumor was treated with a prescription dose of 12.0 Gy and a prescription isodose of 45.0% [Figure 3]d. In the follow-up six months after the last gamma knife radiosurgery, an MRI showed no remnants of the tumor in both the cerebellopontine angles, vermis of the cerebellum or brainstem [Figure 3]e. The patient is free of the disease and is under regular follow-up.
Figure 3: T1-weighted magnetic resonance (MR) images with gadolinium enhancement. (a) Leksell gamma knife treatment planning for residual tumors after the first operation. (b) Metastasis in the brainstem and gamma knife radiosurgery treatment planning. (c) Left-sided tumor recurrence 18 months after the first surgery and gamma knife radiosurgery was carried out for the treatment. Lesions in the vermis cerebelli and the brainstem disappeared. (d) The right-sided tumor recured 27 months after the first gamma knife radiosurgery while the left-sided tumor recurrence was not seen. (e) Half a year after the last gamma kinfe radiosurgery, no distinct signs of tumor remnants were found at the CPAs, vermis cerebelli or brainstem

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 » Discussion Top

Endolymphatic sac tumors are locally aggressive papillary adenocarcinomas originating from the endolymphatic sac. [3] The gene mutation for ELSTs and other neoplasms associated with VHL disease is the same. [4] About 28% of ELSTs are bilateral and mostly seen in patients with VHL disease, whereas, only 1% of bilateral ELSTs occur in other patients. [2] Metastasis of ELST is extremely rare and only one case has been reported to date. [5] The common presentation is progressive or sudden, and the clinical features are sensorineural hypoacusis with ipsilateral facial paralysis. Other clinical features include headache, dizziness, tinnitus, vertigo, cranial nerve paralysis, Vernet's syndrome, and cerebellopontine angle syndrome. [6],[7] The differential diagnosis include other lesions in the cerebellopontine angle, such as, schwannoma, meningioma, jugular paraganglioma, metastatic adenocarcinoma, and choroid plexus papilloma. Early diagnosis and treatment is important in order to preserve hearing and facial nerve function. [8] The diagnostic imaging modalities include computed tomography (CT), including high resolution CT (HRCT), MRI, and digital subtraction angiography (DSA). The CT findings in ELST include lytic lesions at the endolymphatic sac in the petrous bone, central calcific spiculation, and posterior rim calcification. [9],[10] Skull base high-resolution computed tomography (HRCT) can clearly demonstrate the borders of the tumor and the extent of bone erosion. A T1-weighted (non-contrast) MRI sequence often shows hyperintense foci. T1-weighted post-gadolinium scans show variable enhancement, based on the degree of tumor vascularity. T2-weighted sequences show heterogeneous signals. [10] DSA shows the hypervascularity of the mass and the arterial supply of the lesion. [11],[12] Grossly, ELSTs are highly vascular red masses. Microscopically, ELSTs show two main patterns: [13] well-formed papillary fronds and thyroid follicle-like glandular structures. Hemorrhages, calcifications, siderophages, cholesterol clefts, and inflammatory cells can be frequent observations. Immunohistochemistry usually reveals positive staining for S100, cytokeratin, EMA, NSE, GFAP, and vimentin. [14]

Given that the ELSTs are low-grade papillary adenocarcinomas and metastasis is rare, complete surgical resection is the first treatment of choice. However, hypervascularity and encasement of the cranial nerves often make successful resection very difficult. This is probably the reason for very high recurrence rates. For complete resection preoperative angiography and embolization, interoperative electrophysiological monitoring, and microsurgery are suggested. [15],[16] Surgical approaches include the transmastoid, retromastoid or retrolabyrinthine-transdural approaches, which are selected on the basis of the location and extent of the tumor and the patient's preoperative functional deficits. [6],[8] The role of radiotherapy or gamma knife radiosurgery is controversial, and the published series are too few to provide a definite conclusion. Most studies reported an uncertain effect of radiotherapy or gamma knife radiosurgery. [6],[7],[9],[12],[17] Two cases treated with gamma knife radiotherapy, with long-term follow-up, and with no recurrence, have been reported. [5],[18]

In our case, the patient had only sensorineural hypoacusis and facial paresis at the time of the first admission. The lesion in the left cerebellopontine angle was pathologically ELST. The lesions in the right cerebellopontine angle and vermis of the cerebellum were also considered to be ELSTs, based on the image characteristics on the MRI. Probably this is the first report of multiple ELSTs in a patient without VHL disease. The other unique feature of our case is metastases. The literature review reveals a report of only one case of metastatic ELST, distant from the original site of surgery. [5] Our patients had two sites of metastases (vermis of the cerebellum and brainstem). gamma knife radiosurgery showed a good effect on tumor remission. Thus, with an appropriate prescription dose and isodose gamma knife radiosurgery may have an important role in curing the recurrence or metastasis of ELSTs.

 » References Top

1.Hassard AD, Boudreau SF, Cron CC. Adenoma of the endolymphatic sac. J Otolaryngol 1984;13:213-6.  Back to cited text no. 1
2.Bambakidis NC, Megerian CA, Ratcheson RA. Differential grading of endolymphatic sac tumor extension by virtue of von Hippel-Lindau disease status. Otol Neurotol 2004;25:773-81.  Back to cited text no. 2
3.Heffner DK. Low-grade adenocarcinoma of probable endolymphatic sac origin a clinicopathologic study of 20 cases. Cancer 1989;64:2292-302.  Back to cited text no. 3
4.Tibbs RE, Bowles AP, Raila FA. Should endolymphatic sac tumors be considered part of the von Hippel-Lindau complex? Neurosurgery 1997;40:848-55.  Back to cited text no. 4
5.Ferreira MA, Feiz EI, Zabramski JM, Spetzler RF, Coons SW, Preul MC. Endolymphatic sac tumor: Unique features of two cases and review of the literature. Acta Neurochir (Wien) 2002;144:1047-53.  Back to cited text no. 5
6.Yilmaz I, Bolat F, Demirhan B, Aydin V, Ozluoglu LN. Endolymphatic sac papillary tumor: A case report and review. Auris Nasus Larynx 2008;35:276-81.  Back to cited text no. 6
7.Doherty JK, Yong M, Maceri D. Endolymphatic sac tumor: A report of 3 cases and discussion of management. Ear Nose Throat J 2007;86:30-5.  Back to cited text no. 7
8.Megerian CA, Haynes DS, Poe DS. Hearing preservation surgery for small endolymphatic sac tumors in patients with von Hippel-Lindau syndrome. Otol Neurotol 2002;23:378-87.  Back to cited text no. 8
9.Mohindra S, Chhabra R, Mukherjee KK, Gupta SK, Mohindra S, Vashista RK. Contrasting behavior of endolymphatic sac tumors: A report of 2 cases and literature review. Surg Neurol 2008;69:175-80.  Back to cited text no. 9
10.Patel NP, Wiggins RH 3rd, Shelton C. The radiologic diagnosis of endolymphatic sac tumors. Laryngoscope 2006;116:40-6.   Back to cited text no. 10
11.Richards PS, Clifton AG. Endolymphatic sac tumours. J Laryngol Otol 2003;117:666-9.  Back to cited text no. 11
12.Kang M, Khandelwal N, Singh P, Choudhary S, Mukherjee KK. Imaging features of endolymphatic sac tumours: Case report with review of literature. Australas Radiol 2007;51:199-201.  Back to cited text no. 12
13.Luff DA, Simmons M, Malik T, Ramsden RT, Reid H. Endolymphatic sac tumours. J Laryngol Otol 2002;116:398-401.  Back to cited text no. 13
14.Rodrigues S, Fagan P, Turner J. Endolymphatic sac tumors: A review of the St. Vincent's hospital experience. Otol Neurotol 2004;25:599-603.  Back to cited text no. 14
15.Hansen MR, Luxford WM. Surgical outcomes in patients with endolymphatic sac tumors. Laryngoscope 2004;114:1470-4.  Back to cited text no. 15
16.Boccio CM, Raffo GM, Parsini C. Cochlear implantation in a bilateral endolymphatic sac tumor patient. A case report. Int J Pediatr Otorhinolaryngol 2007;71:1803-7.  Back to cited text no. 16
17.Jagannathan J, Lonser RR, Stanger RA, Butman JA, Vortmeyer AO, Zalewski CK, et al. Cochlear implantation for hearing loss associated with bilateral endolymphatic sac tumors in von Hippel-Lindau disease. Otol Neurotol 2007;28:927-30.  Back to cited text no. 17
18.Balasubramaniam S, Deshpande RB, Misra BK. Gamma knife radiosurgery in jugular foramen endolymphatic sac adenocarcinoma. J Clin Neurosci 2009;16:710-1.  Back to cited text no. 18


  [Figure 1], [Figure 2], [Figure 3]

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