Yonago Acta medica 2008;51:101–106

Endolymphatic Sac Tumor, A Patient ReportKensaku Hasegawa, Shingo Murakami*, Masamichi Kurosaki†, Yasuomi Kunimoto,Toshihide Ogawa‡ and Hiroya Kitano
Division of Otolaryngology, Head and Neck Surgery, Department of Medicine of Sensory andMotor Organs, School of Medicine, Tottori University Faculty of Medicine, Yonago 683-8504,*Department of Neuro-otolaryngology, Sensory and Plastic Medicine, Graduate School of Medical Sciences, Nagoya City University, Nagoya 467-0601, †Department of Neurosurgery, Instituteof Neurological Sciences, Tottori University Faculty of Medicine, Yonago 683-8504 and ‡Division of Radiology, Department of Pathophysiological and Therapeutic Science, School of Medicine, Tottori University Faculty of Medicine, Yonago 683-8504 Japan

Endolymphatic sac tumors are rare low malignant neoplasms of the petrous temporalbone, with symptoms referable to auditory, vestibular or facial nerves, which should bestrictly discriminated from benign tumors of the temporal bone. Differential diagnosis between both at the early stages of checkup controls the treatment and prognosis.
Complete surgical resection is the treatment of choice, which commonly provides longterm control. We have experienced a 48-year-old man with progressive hearing loss, unsteadiness and constant tinnitus. Computed tomography and magnetic resonance imaging (MRI) demonstrated a tumor invading the posterior petrous bone, extending to theposterior fossa. In the course of image diagnosis of his disease, we observed diagnostic
efficacy of 3-tesla MRI, which showed excellent lesion visualization even in a small-size
endolymphatic sac tumor. The intraoperative pathologic diagnosis was not available.
Key words: endolymphatic sac tumor; pathologic diagnosis; temporal bone surgery; 3-teslamagnetic resonance imaging

hearing loss, facial paralysis and disequilibrium.
Upon imaging, they show significant dural involvement. Light microscopic patterns may befollicular or papillary and solid. Both patterns
often are mixed in the same tumor. Magnetic
resonance imaging (MRI) variegated lesion of thetemporal bone; multiple foci of high signal intensity indicate the hypervascular part of the tumor,
scattered low-signal foci represent connective
tissue scarring following bleeding. We present apatient with endolymphatic sac tumor, describing
clinical, imaging, intraoperative and pathologic
features.

Endolymphatic sac tumors, rare lesions of thepetrous temporal bone, arise in the vicinity of theinner ear but may extend to both the posterior fossa and the middle ear. In 1984, Hassard et al. proposed that the endolymphatic sac could give riseto adenomatous papillary tumors (Hassard et al.,1984). Five years later, Heffner (1989) reviewed
20 papillary-cystic temporal bone tumors, reporting the origin as the endolymphatic sac. Despitea benign histopathologic appearance, these lesions
are regarded clinically adenocarcinomas sincethen often are locally invasive. Endolymphatic
sac tumors frequently manifest sensorineural

Abbreviations: CT, commputed tomography; MRI, magnetic resonance imaging; 3T, 3-tesla101

K. Hasegawa et al.

Patient Report
A 48-year-old man was admitted to Tottori University Hospital in 2005 because of right-sided
sensorineural hearing loss accompanied by persistent tinnitus. He also had recurrent episodesof disequilibrium and mild headache. Otologic
examination was performed, including pure-toneaudiometry, impedance testing and vestibular
testing. Audiometric data indicated complete
hearing loss in the right-ear, with normal impedance. Caloric testing demonstrated no response
to irrigation of the right external auditory canal.
Otoscopic observations, facial nerve examinationand findings concerning remaining cranial nerves
were normal. Systemic examination for vonHippel-Lindau disease was performed including
brain and dorsal MRIs, whole body computed tomography (CT), ophthalmologic and also genetic
examination (the deficit of 3p25-26) revealing all
negative results. CT of the temporal bone showed
an osteolytic mass on the posteroinferior side of
the petrous bone. The mass extended to the duraof the posterior fossa and invaded the right innerear. On 3T MRI with gadolinium enhancement,
the tumor showed heterogeneous signal intensity.
Scattered low intensity areas appeared among
multiple high-intensity foci in both T1- and T2weighted images (Figs. 1 and 2). Angiographydemonstrated a hypervascular lesion in the petrous
bone supplied by the occipital and ascending pharyngeal arteries. Prior to surgery, these arteries
were embolised (Fig. 3). The patient underwent
mastoidectomy, disclosing a hard mass between
the posterior fossa and the lateral hemicanal. The
mass extended to the jugular bulb, internal auditory canal, retrofacial space and infralabyrinthine
air cells. After exposing the sigmoid sinus by

A

B

C

D

Fig. 1. Radiological findings in the present patient.
A: Computed tomography (CT) scan of the temporal bone;
B: T1-weighted 3-tesla (3T) magnetic resonance imaging (MRI);
C: T1-weighted 3T MRI after gadolinium administration;
D: T2-weighted 3T MRI.
The tumor arises along the right petrous ridge, producing bone erosion near the inner ear. Heterogenous signal intensity is seen by T1- and T2-weighted MRI (arrow).

102Endolymphatic sac tumor

A

B

Fig. 2. Typical images in the present patient using 1.5-tesla MRI (A: T1-weighted; B: T2-weighted). Tumor visualization is inferior to that with 3-tesla MRI.

making a Bill’s island bone flap, the tumor was
found to extend to the posterior fossa dura andalso the middle fossa dura. We then obtained
tissue for intraoperative pathologic examination.
The first 2 small specimens from the surface ofthe mass were not diagnostic of tumor, showing
granulomatous reaction with fibrosis, hypervascularity and cholesterol deposition. As preoperative
imaging showed a tumor, we submitted anotherspecimen from a deeper, reddish portion of themass, obtaining an intraoperative pathologic diagnosis of endolymphatic sac tumor. The 3rd tumor
was resected in a piece meal fashion, resulting inincomplete removal with a portion of the tumor
tissue attached to the jugular bulb.
Postoperative pathologic examination of theresected tissue demonstrated cuboidal to highcolumnar atypical cells with round nuclei, a papillary arrangement (Fig. 4) and an invasion of thebony structures. Immunochemical study showed
the tumor cells to be reactive for cytokeratin
AE1/3, vimentin, epithelial membrane antigen andneuron-specific enolace, focally reactive for glial
fibrillary acidic protein. Tumor cells were negative for carcinoembryonic antigen, chromogranin,
synaptophysin, cluster designation 34, cluster
designation 117, carbohydrate antigen 19-9, S-100
protein, anti lymphatic endothelium marker D240 and Ki-67 (expression < 1%).
On the 1st postoperative day, the patient had
slight cerebrospinal fluid leakage from the thinned

Fig. 3. Right external carotid arteriogram demonstrates
blood supply from the postauricular artery.

Fig. 4. Low-power photomicrograph of the resection
specimen demonstrates a papillary growth pattern characteristic of endolymphatic sac tumor (hematoxylin andeosin, 100).

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area of the posterior fossa dura. This complication was repaired under general anesthesia. No
other complications occurred. Stereotactic radiotherapy with 65 Gy was administered after the
repair surgery. The patient has undergone regularfollow-up for 30 months. CT and MRI have detected no residual tumor enlargement.

low-intensity areas were admixed with multiple
high-intensity foci on both T1- and T2-weighted
images. A portion of the dura showed gadolinium enhancement indicating tumor invasion.
Angiography depicted a hypervascular lesion in
the petrous pyramid, supplied predominantly bya branch of the occipital artery. The differential
diagnosis included paraganglioma, endolymphatic
sac tumor, metastasis from an occult primary cancers, chondrosarcoma and cholesterol granuloma.
Paraganglioma and endolymphatic sac tumor
were most likely based on tumor location, bone
destruction, signal intensity patterns on MRI and
the feeding artery. Endolymphatic sac tumor is alocally aggressive malignant tumor and paraganglioma is a benign neoplasm, preoperative differentiation between the 2 diagnoses was importantfor planning surgical approach for resection. Unfortunately, endolymphatic sac tumor could be diagnosed only intraoperatively. Ricards and Clifton (2003) reported that endolymphatic sac tumor
was heterogeneous in signal intensity pattern, withheterogeneous gadolinium enhancement. Multiple
high-intensity foci on both T1 and T2-weighted
images indicated the presence of methemaglobin,
blood-filled or proteinaceous cysts and cholesterol
clefts. Mukherji et al. (1997) performed MRI in
15 cases of endolymphatic sac tumor, noting thatappearance varied with tumor size. Lesions 2 cm
or less in diameter was heterogeneous, with a rimof increased signal on T1-weighted images. Tumors were enhanced with gadolinium administration. Larger tumors showed intratumoral areas ofincreased signal on non-gadolinium T1-weighted
images. Patel et al. (2006) reviewed 31 casesof endolymphatic sac tumor and described T1weighted MRI post-gadolinium scans showed heterogeneous enhancement in all cases (100%). T2weighted images showed heterogeneous signals inall lesions (100%). Those authors proposed thatsignal characteristics could be used to differentiate endolymphatic sac tumor from other lesions
occurring in this region (Mukherji et al., 1997).
Our patient’s tumor was 2 cm in diameter, making
it comparable to the smaller tumors above. How-

Discussion
Endolymphatic sac tumors are rare tumors of thetemporal bone, recently have been recognized as a
distinct entity after previously having been classified with other papillary middle ear tumors (Gaffey
et al., 1988, 1994; Li et al., 1993). In 1989, Heffner reviewed 20 papillary tumors of the temporalbone, concluding that all were low-grade adenocarcinomas likely to have originated from the endolymphatic sac (Heffner, 1989). Only 1 case had
been reported prior to that, by Hassard et al. (1984),
who definitively identified the tumor’s origin as
the endolymphatic sac upon unexpectedly finding
a mass during sac decompression surgery.
Chief clinical manifestations of endolymphatic sac tumors include sensorineural hearing
loss, disequilibrium, facial nerve paralysis andpalsies involving other nearby cranial nerves.
Although complications of endolymphatic sactumor vary with extent of tumor growth, the mostconsistent early symptom is sensorineural hearing
loss. Endolymphatic sac tumor is difficult to differentiate from other lesions of the temporal boneand posterior fossa, typically being discovered at
an advanced stage and lacking specific symptoms.
In our patient an otologic examination indicatedonly a temporal bone lesion of unknown nature.
CT, MRI and angiography were needed to determine that a tumor was present and determinesome of its characteristics. CT imaging displayed
a destructive lesion of the temporal bone involving
the posterior aspect of the petrous pyramid, whichlies mainly within the posterior part of the petrous
bone. MRI at 3T with gadolinium enhancement
disclosed a heterogeneous lesion, while scattered104

Endolymphatic sac tumor

ever, 3T MRI showed a heterogeneous pattern
without a rim of increased signal in T1-weighted
images without gadolinium. Typical images comparing 3T MRI (Fig. 1) with 1.5-tesla MRI (Fig. 2)
demonstrate a favorable higher signal-to-noise
ratio using 3T MRI. This modality may provide
improved imaging for use with intraoperative
navigation systems.
Pathologically, endolymphatic sac tumors appeared nonaggressive, but these tumors often are
locally invasive (Luff et al., 2002). Heffner (1989)
reported endolymphatic sac tumor morphology as
including complex arrays of interdigitating papillary processes infiltrating surrounding tissue, embedded in dense fibrous tissue showing evidenceof past hemorrhage as well as cholesterol clefts
and inflammatory cells. The latter tumor characteristics posed difficulties in intraoperative pathologic assessment, which were surmounted only
by resecting the superficial part of the tumor andthen submitting a specimen from the deep, hypervascular part of the lesion. Immunopathologicalfindings of our patient were positive expression ofcytokeratin AE1/3, vimentin, glial fibrillary acidic
protein and negative of carcinoembryonic antigen,synaptophysin, carbohydrate antigen 19-9 andanti lymphatic endothelium marker D2-40. These
results corresponded to the reports of Asano et al.
(1999) and Rodrigues et al. (2004). Their reports
showed the activity of the endolymphatic sac tumors related to the level of Ki-67 and the characteristics of tumors were expression of glial fibrillary acidic protein and vimentin. Fortunately, thelevel of Ki-67 was below 1% in our patient, deliberate long-term observation was necessary for thepatient.
Ultimately, tumor removal was incomplete
because dense connective tissue remaining in
the operative field interfered with and precluded
enbroc resection. Devaney et al. (2003) reported
that most patients with endolymphatic sac tumor
were difficult to cure by surgical resection. Treatment options include embolisation followed bysubtotal resection, as well as other strategies;
nonetheless, surgical excision remains the main-

stay of therapy for endolymphatic sac tumor. Efficacy of stereotactic radiotherapy is not known,
but our patient underwent this treatment in viewof subtotal resection (Heffner, 1989; Megerian
et al., 1995; Hansen and Luxford, 2004). Two
previous reports described remote metastasis ofendolymphatic sac tumor; Ferreira et al. (2002)
and Robson et al. (1990). In 2005, Bambakidis etal. reported the 1st case of metastasis to the spine(Bambakids, 2005). Given the uncertainties, ourpatient will need careful follow-up connecting
both local recurrence and metastasis.
References
1 Asano K, Sekiya T, Hatayama T, Tanaka M, Takemura A, Suzuki S, et al. A case of endolymphatic
sac tumor with long-term survival. Brain Tumor
Pathol 1999;16:69-76.
2 Ba mba k id is NC, Rod r ig ue T, Meger ia n CA,
Ratcheson RA. Endolymphatic sac tumor metastaticto the spine. Case report. J Neurosurg Spine
2005;3:68–70.
3 Devaney KO, Ferlito A, Rinaldo A. Endolymphatic
sac tumor (low-grade papillary adenocarcinoma)of the temporal bone. Acta Otolaryngol 2003;123:
1022–1026.
4 Fer rei ra M AT, Feiz-Er fa n I, Zabra msk i J M,
Spetzler RF, Coons SW, Preul MC. Endolymphatic
sac tumor: unique features of two cases andreview of the literature. Acta Neurochir (Wien)
2002;114:1047–1053.
5 Ga f fey M J, M i l ls SE , Boyd JC. Agg ressive
papillary tumor of middle ear/temporal bone andadnexal papillary cystadenoma. Manifestationsof von Hippel Lindaw disease. Am J Surg Pathol
1994;18:1254–1260.
6 Gaffey MJ, Mills SE, Fechner RE, Intemann SR,
Wick MR. Aggressive papillary middle-ear tumor.
A clinicopathologic entity distinct from middle-ear
adenoma. Am J Surg Pathol 1988; 12:790–797.
7 Hansen MR, Luxford WM. Surgical outcomes inpatients with endolymphatic sac tumors. Laryngoscope 2004;114:1470–1474.
8 Hassard AD, Boudreau SF, Cron CC. Adenoma of
the endolymphatic sac. J Otolaryngol 1984;13:213–
216.
9 Heffner DK. Low-grade adenocarcinoma of probableendolymphatic sac origin. A clinicopathologicalstudy of 20 cases. Cancer 1989;64:2292–2302.
10 Li JC, Brackmann DE, Lo WW, Carberry JN, House
JW. Reclassification of aggressive adenomatous105

K. Hasegawa et al.

mastoid neoplasms as endolymphatic sac tumors.
Laryngoscope 1993;103:1342–1348.
11 Luff DA, Simmons M, Malik T, Ramsden RT, Reid
H. Endolymphatic sac tumours. Pathology in focus.
J Laryngol Otol 2002;116:398–401.
12 Megerian CA, McKenna MJ, Nuss RC, Maniglia
AJ, Ojemann RG, Pilch BZ, et al. Endolymphatic
sac tumors: histopathologic confirmation, clinicalcharacterization, and implication in von HippelLindau disease. Laryngoscope 1995;105:801–808.
13 Mu k her ji SK, A lber na z VS, Lo W W, Ga ffey
MJ, Megerian CA, Feghali JG, et al. Papillary
endolymphatic sac tumors: CT, MR imaging, andangiographic findings in 20 patients. Radiology
1997;202:801–808.
14 Patel NP, Wiqqins RH 3rd, Shelton C. The radiologic

diagnosis of endolymphatic sac tumors. Laryngoscope
2006;116:40–46.
15 Richards PS, Clifton AG. Endolymphatic sactumours. Radiology in Focus. J Laryngol Otol
2003;117:666–669.
16 Robson AK, Eveson JW, Smith IM, Maw AR.
Papillary adenocarcinoma of the middle ear. J
Laryngol Otol 1990;104:915–916.
17 Rodrigues S, Fagan P, Turner J. Endolymphatic
sac tumors: a review of the St. Vincent’s hospital
experience. Otol Neurotol 2004;25:599–603.
Received August 4, 2008; accepted September 16, 2008
Corresponding author: Kensaku Hasegawa, MD

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