Endolymphatic sac tumours

Abstract

This review article surveys clinical and pathological literature on endolymphatic sac tumours (ELST) and summarizes characteristics that describe the entity. ELST are rare neuroectodermal neoplasms in the petrous bone, originating from inner ear structures. They can be encountered sporadically or in von Hippel-Lindau disease. The most prominent symptom is sensorineural deafness. Historically, nomenclature of invasive adenoid tumours in the petrous bone has been divergent, the term papillary adenocarcinoma used most frequently. Histologically, they have a follicular or papillary and adenoid pattern that can be easily confused with various other neoplastic conditions including metastatic carcinoma. It remains to be verified whether similar tumours (papillary adenocarcinomas) can originate from the middle ear. Middle ear adenomas have a similar appearance but probably originate from neural crest cells in the middle ear. ELST can express a variety of epitopes (including cytokeratin and neuroectodermal markers) which can be detected immunohistochemically. In cases in von Hippel-Lindau disease the cerebello-pontine angle should be included in routine radiological examinations to detect ELST before the tumours lead to deafness. In apparently sporadic cases of ELST, genetic testing for von Hippel-Lindau disease should be considered. Correct distinction of ELST from metastatic carcinoma prevents futile searches for unknown primary tumours.

Cytology of Endolymphatic Sac Tumor

“…Although the clinicopathologic and radiographic features have been well documented, the cytologic features of ELST have not been previously described (1)(2)(3)(4)(5). We report the cytologic findings of an ELST from the cyst fluid of a recurrent ELST in the left temporal region of a 77-year-old man.…”

Treatment of endolymphatic sac tumour (Papillary adenocarcinoma) of the temporal bone

“…8,10 From its origin, the tumour growth can affect the petrous bone itself and its posterior surface in the posterior cranial fossa, facing the cerebellopontine angle. 11 From the endolymphatic sac, the tumour may erode the vestibule, the posterior semicircular canal and the mastoid cavity. 9 Subsequently, the mastoid tumour can involve the jugular bulb and the facial nerve from where it can spread anteriorly to the middle ear.…”

Endolymphatic Sac Tumor Associated with a Von Hippel-Lindau Disease Patient: An Immunohistochemical Study

“…Many hypervascular tumors, such as hemangioblastomas, renal cell carcinomas, and pheochromocytomas, are known to be manifestations of VHL. Recently the fact that ELST also has a significant association with VHL has been recognized (2,6,(15)(16)(17), and several VHL patients have presented with bilateral ELSTs (6,7). This suggests that tumorigenesis of ELST is relevant to the genetic aberration of VHL.…”

“…ELST histologically shows epithelial features, such as papillary architecture, glandular formation and a colloid-like structure. Immunohistochemical expression of cytokeratins (CKs) has been noted in ELST, and, thus, this tumor is believed to be an epithelial tumor (2)(3)(4)(5)(6)(7)(8). Because ELST is radiographically hypervascular, preoperative misdiagnoses of paraganglioma, glomus tumor and other temporal tumors occasionally have been given (1).…”

“…It often shows invasion to surrounding temporal bone (3,4,12) and there are reports of several patients who received incomplete resection and experienced a recurrence of the tumor (7,21), although proliferative activity has been unknown in most ELSTs.…”