Endolymphatic sac tumor

[2][3] Patients with ELST may present clinically with progressive or fluctuating, one sided sensorineural hearing loss which may mimick Ménière's disease due to the development of tumor associated endolymphatic hydrops.

[4] Patients may also present with other symptoms related to von Hippel–Lindau syndrome in other anatomic sites, which will result in imaging evaluation of the head.

Computed tomography shows a multilocular, lytic destructive temporal bone mass, centered on the vestibular aqueduct (between internal auditory canal and sigmoid sinus).

The VHL protein is involved in up-regulation of hypoxic response via the [[hypoxia inducible factor [HIF]-1 alpha]].

The tumor destroys the mastoid air spaces and extends into the middle ear and/or posterior cranial fossa.

[10] The germline mutations of VHL tumor suppressor gene will be found on 3p25-26 (short arm of chromosome 3), usually between base pair 10,158,318 to 10,168,761.

From a pathology perspective, an endolymphatic sac tumor needs to be separated from metastatic renal cell carcinoma, metastatic thyroid papillary carcinoma, middle ear adenoma, paraganglioma, choroid plexus papilloma, middle ear adenocarcinoma, and ceruminous adenoma.

The tumor involves the endolymphatic sac, a portion of the intraosseous inner ear of the posterior petrous bone.

Post contrast T1 weighted MRI demonstrates intense enhancement of both the eye and the endolymphatic sac tumor in patient with VHL.
CT in patient with VHL syndrome through the petrous ridge demonstrates bone erosion at the site of the endolymphatic sac tumor, typical of the locally aggressive behavior of this tumor (curved arrow).
An intermediate power image of an endolymphatic sac tumor with bone (upper left).
A high power image of an endolymphatic sac tumor showing clear cytoplasm in cuboidal cells lined up along papillae.