Current Treatment of Endolymphatic Sac Tumor of the Temporal Bone

Abstract

An endolymphatic sac tumor (ELST) is a rare, indolent but locally aggressive tumor arising in the posterior petrous ridge. Patients present with sensorineural hearing loss and tinnitus. As the tumor progresses, patients may experience vertigo, ataxia, facial nerve paresis, pain and otorrhea. Most patients present in their 4th or 5th decade with a wide age range. Patients with von Hippel-Lindau disease have an increased likelihood of developing ELST. Histologically, ELST is a low-grade adenocarcinoma. As it progresses, it destroys bone and extends into adjacent tissues. The likelihood of regional or distant metastases is remote. The optimal treatment is resection with negative margins. Patients with positive margins, gross residual disease, or unresectable tumor are treated with radiotherapy or radiosurgery. Late recurrences are common, so long follow-up is necessary to assess efficacy. The likelihood of cure depends on tumor extent and is probably in the range of 50-75%.

Keywords: Endolymphatic sac tumor; Heffner tumor; Radiation therapy; Surgery; Temporal bone; von Hippel–Lindau disease.

Fig. 1

a, b MRI showing a mass that is hyperintense tumor-like mass (asterisk) on contrast enhanced T1 sequence. c, d CT showing bone destruction of the posterior aspect of the petrous ridge. Arrows point to the tumor

Fig. 2

a Hematoxylin and eosin-stained section (×100 magnification). Microscopy of an endolymphatic sac tumor shows dilated epithelial cell-lined follicle-like cystic structures with secretions. The cells are uniform with small hyperchromatic nuclei. b Hematoxylin and eosin-stained section (×200 magnification). At higher magnification, the uniformity of the endolymphatic sac tumor cells are noted with round nuclei and no mitoses. The architectural pattern is undulating with papillary formations. c Hematoxylin and eosin-stained section (×200 magnification). The enlargement and clearing of the cytoplasm in this endolymphatic sac tumor mimics renal cell carcinoma. The tumor here is noted to be vascular and adjacent to bone (top). This tumor must be differentiated from renal cell carcinoma which also occurs in VHL patients. d Immunohistochemical evaluation for pancytokeratin (×200 magnification) highlights the epithelial cells lining the papillary structures in this endolymphatic sac tumor

Fig. 3

a 1 Tumor is located under a bulging dura; 2 VIII cranial nerve; 3 lower cranial nerves. b 1 Operative cavity in the posterior aspect of the petrous ridge; 2 VIII cranial nerve; arrows indicate the dural resection margins