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King Khalid Military City Hospital Kingdom of Saudi Arabia
Habib Bourguiba Hospital Sfax 3029, Tunisia
The endolymphatic sac was first recognized as a possible source of neoplasm by Hassard et al. [1] and Michaels [2] when they discovered incidentally a small vascular lobular tumor in the sac during a decompression operation. The endolymphatic sac tumor was previously called "cerebellopontine angle ceruminoma," "extradural choroid plexus papilloma," "metastatic papillary adenocarcinoma of unknown origin," and "middle ear adenoma" [3, 4]. The association of endolymphatic sac tumors and von Hippel-Lindau (VHL) disease has been reported [3, 4]. We report a rarely illustrated association of endolymphatic sac tumor and a cerebellar hemangioblastoma in a woman with previously unknown VHL disease.
A 54-year-old woman was admitted to our hospital for exaggeration of intracranial pressure symptoms (chronic headache and nausea). She also complained of left hearing loss, which had been worsening gradually for 3 years. On physical examination, cerebellar symptoms and discrete left-sided facial paresis were observed. Brain CT scans obtained before and after injection of contrast material showed a large left-sided cerebellar cystic mass displacing the fourth ventricle, associated with a left-sided space-occupying lesion in the petrous bone. The bony mass was eroding the posterior aspect of the petrous bone and was bulging in the cerebellopontine angle (Fig. 7A). Moderate supratentorial hydrocephalus was observed. MR imaging was performed on a 1.0-T unit (Magnetom Impact; Siemens, Erlangen, Germany). Multiplanar turbo spin-echo T1- and T2-weighted images were obtained before (Figs. 7B and 7C) and after (Fig. 7D) gadolinium injection. The left cerebellar cystic mass measured 4.5 cm in diameter and displayed a small mural nodule strongly enhancing after gadolinium injection. The left-sided temporal mass showed multiple scattered hypersignal areas with lobulated outlines and intense contrast enhancement on both T1- and T2- weighted images. The imaging features were strongly suggestive of VHL disease with left cerebellar hemangioblastoma and endolymphatic sac tumor. The diagnosis was confirmed histologically after both tumors were surgically excised.
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Most endolymphatic sac tumors appear to occur sporadically [3, 4], and an association with VHL disease has been reported rarely. Mukherji et al. [4], in a multicentric retrospective study of 20 VHL cases, reported only one case of this association. Many authors agree that patients with VHL disease present with greater risk of developing endolymphatic sac tumors, even bilaterally [4]. The prevalence of the latter tumor in VHL disease was estimated to be 7% (Marsot Dupuch K, personal communication), and this prevalence is much higher in VHL patients with hearing loss. On histopathologic examination, endolymphatic sac tumors show papillary adenomatous architecture [3, 4], consisting of a complex interdigitating papillary process infiltrating the surrounding connective tissue and bone [4]. The tumor contains areas of hemorrhage, hemosiderin, and cholesterol clefts with scattered inflammatory giant cell reactions [3, 4]. The endolymphatic sac tumor is a slow-growing tumor and may recur locally but has not, to our knowledge, been reported to metastasize. Endolymphatic sac tumors are located in the posterior area of petrous bone and frequently involve the dura [1]; they are hypervascular locally invasive bone-destroying tumors and are frequently associated with the presence of reactive new bone [3, 4]. Unilateral hearing loss and vestibular dysfunction are prominent, but late, symptoms revealing the tumor. The duration of hearing loss ranges from 6 months to 18 years. Some authors insist on the early diagnosis of endolymphatic sac tumors in patients with VHL disease using audiologic tests and periodic MR screening to detect early papillary endolymphatic sac tumors before the deterioration of audition. Facial nerve palsy is seen once the tumor becomes large (>3 cm). CT and MR findings have strengthened the theory that the endolymphatic sac is the origin of papillary adenomatous tumors of the temporal bone. Indeed, the small endolymphatic sac tumor destroys the retrolabyrinthine petrous bone in the region of the vestibular aqueduct and then spreads to the supra- and infralabyrinthinem and mastoidotympanic regions [3, 4]. The cochlea is always spared. On CT, the tumor bone margins are geographic or "moth-eaten," and the intratumoral bone appears reticular or spiculated [4]. All papillary endolymphatic sac tumors had a thin peripheral rim of calcification, representing the expanded cortex of the petrous bone [4]. Sparing of the jugular foramen helps distinguish the endolymphatic sac tumors from jugulare or jugulotympanic glomic tumors [4]. On MR imaging, the small tumors show heterogeneous signal with a peripheral rim of increased signal intensity, and on T1-weighted images, these tumors show heterogeneous intratumoral contrast enhancement. The presence of intratumoral scattered areas of increased signal intensity on T1-weighted images is related to the presence of breakdown products of subacute hemorrhage, cholesterol clefts, and proteinaceous cysts in the large tumors [4]. On angiography, the tumor displays a high degree of vascularity, with blood supply from the ascending pharyngeal and stylomastoid arteries.
Preoperative embolization is helpful for achieving complete and driest surgical excision.
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  R. S. Leung, S. V. Biswas, M. Duncan, and S. Rankin Imaging Features of von Hippel-Lindau Disease RadioGraphics, January 1, 2008; 28(1): 65 - 79. [Abstract] [Full Text] [PDF]
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