Endolymphatic sac tumor
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Endolymphatic sac tumors are very rare, locally invasive tumors of endolymphatic sac. Early detection of these tumors is critical, because early surgical intervention may prevent further hearing loss. Endolymphatic sac tumors do not metastasize but are highly locally aggressive.
Typically endolymphatic sac tumors are encountered in young individuals, with a mean age at onset of 22 years 2.
Endolymphatic tumors are most often associated with von Hippel-Lindau disease and are detected in 11-16% patients with von Hippel-Lindau disease 2. However, in ~60% of patients with von Hippel-Lindau disease and vestibulocochlear symptoms, there is no evidence on imaging of an endolymphatic sac tumor 2.
When these tumors are present in the setting of von Hippel-Lindau disease, then 30% of tumors are bilateral 2.
Endolymphatic sac tumors typically present with the following symptoms and signs:
hearing loss: 95%
vertigo or disequilibrium: 62%
aural fullness: 29%
facial paresis: 8%
These tumors are composed of two histological types:
mixed type: generally confined
papillary adenomatous type: more aggressive and often locally invades the temporal bone
Generally, endolymphatic sac tumors always arise within the vestibular aqueduct, involving the endolymphatic sac or duct. Therefore, the lesion is centered in the posterior (retrolabyrinthine) petrous bone.
erosion of petrous bone in an infiltrative or "moth-eaten" pattern
central calcific spiculation and posterior rim calcification 5
often intense enhancement
Signal characteristics include 5
T1: most show foci of hyperintensity
T1 C+ (Gd): heterogeneous enhancement, involving the non-cystic component of the tumor
T2: heterogeneous signal
Treatment and prognosis
Surgical excision is the treatment of choice when possible 3.
History and etymology
It was first described in 1989 by Dennis K Heffner, an American physician 4. Earlier than this they were probably misdiagnosed as choroid plexus tumors, adenomas, and adenocarcinomas of posterior fossa or cerebellopontine angle.
Possible imaging differential considerations include:
center of the lesion will be at the jugular bulb rather than the vestibular aqueduct
expansion of aqueduct, with smooth margins
normal shape of the aqueduct maintained
located in the petrous air cells
bone around the aqueduct is not usually aerated
most often located in the petrous apex, not vestibular aqueduct
hyperostotic underlying bone
- 1. Choyke PL, Glenn GM, Walther MM et-al. von Hippel-Lindau disease: genetic, clinical, and imaging features. Radiology. 1995;194 (3): 629-42. Radiology (abstract) - Pubmed citation
- 2. Lonser RR, Kim HJ, Butman JA et-al. Tumors of the endolymphatic sac in von Hippel-Lindau disease. N. Engl. J. Med. 2004;350 (24): 2481-6. doi:10.1056/NEJMoa040666 - Pubmed citation
- 3. Poletti AM, Dubey SP, Colombo G, Cugini G, Mazzoni A. Treatment of endolymphatic sac tumour (Papillary adenocarcinoma) of the temporal bone. (2016) Reports of practical oncology and radiotherapy : journal of Greatpoland Cancer Center in Poznan and Polish Society of Radiation Oncology. 21 (4): 391-4. doi:10.1016/j.rpor.2015.06.003 - Pubmed
- 4. Heffner DK. Low-grade adenocarcinoma of probable endolymphatic sac origin A clinicopathologic study of 20 cases. (1989) Cancer. 64 (11): 2292-302. Pubmed
- 5. Patel NP, Wiggins RH, Shelton C. The radiologic diagnosis of endolymphatic sac tumors. (2006) The Laryngoscope. 116 (1): 40-6. doi:10.1097/01.mlg.0000185600.18456.36 - Pubmed