Endolymphatic sac tumor

Case contributed by Dr Ernest Lekgabe


The patient presented with episodic vestibular dysfunction.

Patient Data

Age: 65 years
Gender: Male

Small tumor with hyperdense foci centered in fovea of the left endolymphatic sac. Subtle adjacent permeative bone changes.


Small slightly lobulated intrinsic T1 hyperintense and mildly T2 hyperintense tumor centered in fovea of the left endolymphatic sac.

The tumor demonstrates solid enhancement. It contacts the left sigmoid sinus without invading the sinus. It protrudes slightly into the posterior cranial fossa.


10 months post the initial CT and MRI studies.

The tumor has slightly increased in size.
Post retro labyrinthine resection.

Case Discussion

The patient went on to have a resection. 



An irregularly shaped piece of tan tissue, 14x9x6mm. 


The sections show a moderately cellular tumor. It forms elongated nests and acinar-like structures. Some contain calcific deposits and psammoma bodies. The tumor cells have round nuclei, inconspicuous nucleoli and moderate amounts of 'oncocytic type' eosinophilic cytoplasm.

The tumor cells are CAM5.2, AE1/3, CK7, EMA, S-100 and SOX-10 positive. Progesterone receptor, melan-A, synaptophysin, TTF-1 and thyroglobulin are negative.

The PAS stain shows no fungi. The Ziehl-Neelsen stain shows no acid fast bacilli.

Though the architecture is not quite papillary but given the immunoprofile and the site, the features are consistent with papillary tumor of the endolymphatic sac.


Papillary tumor of the endolymphatic sac.

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Case information

rID: 53569
Published: 24th May 2017
Last edited: 16th Jul 2018
System: Head & Neck
Inclusion in quiz mode: Included

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