Answer of November 2009

Clinical History:

A 56 years old man whom has history of von Hippel-Lindau disease with hemangioblastoma resected. Complained of gradual onset of left side hearing loss and dizziness for 2 years. MRI brain was performed (T1 axial, T2 Axial, FLAIR coronal, T1 + C axial and coronal)

Diagnosis:

Bilateral endolymphatic sac tumors

Discussion:

MR brain showed a multiloculated heterogeneous signal intensity mass involving left temporal bone. The mass closely encase left 7th and 8th cranial nerves. No direct involvement of left internal auditory meatus is identified. The mass was later confirmed histologically for endolymphatic sac tumor. Another subtle endolymphatic sac tumor is also seen in right side.

Endolymphatic sace tumor is adenomatous tumor arising from the temporal bone. It is well known in association with von Hippel-Lindau disease. The prevalence of association is 7%. The tumor contains areas of hemorrhage, hemosiderin and cholesterol clefts with scattered inflammatory giant cell reactions. Endolymphatic sac tumor is a slow-growing tumor and may invade to local structure.
Patient may complaint of hearing loss, facial nerve palsy and vestibular dysfunction.

Imaging findings of endolymphatic sac tumor showed destruction of retrolabyrinthine petrous bone in the region of vestibular aqueduct and invade into supra and infralabyrinthine and mastoidotympanic regions. The cochlea is always spared. On CT scan, the tumor showed geographic or moth-eaten bone destruction and intratumoral reticular or speculated bone structures. Sparing of the jugular foramen may helps to distinguish from glomus tumor.
MR findings of endolymphatic sac tumor showed heterogenous signal mass with increased T1 signal, which signify the presence of blood product. Heterogenous enhancement of the mass lesion is seen in postcontrast images.
Endolymphatic sac tumor required surgical excision and preoperative embolization may help to decrease the tumor vascularity.