Endolymphatic sac tumour
Endolymphatic sac tumours (ELST) are very rare, locally invasive tumours of endolymphatic sac. Early detection of these tumours is critical, because early surgical intervention may prevent further hearing loss. Endolymphatic sac tumours do not metastasize but are highly locally aggressive.
Typically endolymphatic sac tumours are encountered in young individuals, with a mean age at onset is 22 years 2.
Endolymphatic sac tumours typically present with the following symptoms and signs:
- hearing loss: 95 %, acute in 43% and stepwise in the second half
- tinnitus: 92%
- vertigo or disequilibrium: 62%
- aural fullness: 29%
- facial paresis: 8%
These tumours are composed of two histological types:
- mixed type: generally confined
- papillary adenomatous type: more aggressive and often locally invades the temporal bone
Endolymphatic tumours are most often associated with von Hippel-Lindau disease (vHL) and are detected in 11-16% patients with vHL 2. That having been said, in almost 60% of patients with vHL and vestibulocochlear symptoms, there is no evidence on imaging of an endolymphatic sac tumour 2.
When these tumours are present in the setting of vHL, then 30% of tumours are bilateral 2.
Always arise from and involve the endolymphatic sac or duct.
When visible, it gives a picture of bone erosion and the "moth-eaten" petrous bone. Endolymphatic sac tumours commonly enhance intensely on CT.
Signal characteristics include:
- T1: may show high-intensity
- T1 C+ (Gd): typically show enhancement in the non-cystic component of the tumour
- T2: often of heterogeneous signal
History and etymology
It was first described in 1989 by Heffner et al. Earlier than this they were probably misdiagnosed as choroid plexus tumours, adenomas, and adenocarcinomas of posterior fossa or cerebellopontine angle.
Possible imaging differential considerations include
glomus jugulare tumour
- the centre of the lesion will be in the jugular bulb rather than the vestibular aqueduct
enlarged vestibular aqueduct
- smooth margins
- maintains the normal shape of the aqueduct
- located in the petrous air cells.
- the bone around the aqueduct is not usually aerated
- most often located in the petrous apex
- hyperostotic underlying bone
- bony metastasis
- 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
Inner ear pathology
inner ear anatomy
- enlarged vestibular aqueduct
- semicircular canal dysplasia
- classification of cochlear anomalies
- infection and inflammation
- trauma and miscellaneous