PMC4065704_01
A pure-tone audiometry before surgical treatment shows a moderate, pantonal, conductive hearing loss in the left ear.
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The pure-tone audiometry revealed a moderate, pantonal, conductive hearing loss in the left ear (Figure 1).
CT imaging (a) with axial (b) and coronal (c) scans demonstrated an irregular, hypodense, and expansile lytic lesion of the mastoid process of the left petrous bone extending to involve both the left medial mastoid and the middle ear, with a subtotal erosion of ossicular chain and a partial bone destruction of the "tegmen tympani" (see arrows). The mass did not appear to affect the semicircular canals, the canal of the facial nerve, and the internal auditory canal.
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Computed tomography (CT) demonstrated an irregular, hypodense, and expansile lytic lesion of the mastoid process of the left petrous bone extending to the middle ear, with a subtotal erosion of ossicular chain and the "tegmen tympani." The mass did not appear to affect the semicircular canals, the canal of the facial nerve, and the internal auditory canal (Figure 2).
Axial T1-weighted cerebral MRI confirmed the presence of a lesion of increased signal, similar to brain tissue (a); the tumor (22 x 15 x 11 mm) enhanced with gadolinium in the medial portion of middle ear and in the tubaric region (b).
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T1-weighted sequences, enhanced in the medial portion of the middle ear and in the tubaric region (Figure 3).
Histopathologic study of ELST. The histologic sections showed the papillary and glandular-cystic architecture of the ELST (a) (H&E, 50x). There were cystic glandular spaces filled with colloid-like material which was remarkably similar to thyroid tissue (H&E, 200x) (b). The papillary structures were lined by a single layer of low cuboidal epithelial cells. There were minimal cellular pleomorphism and rare mitotic activity (H&E, 200x) (c).
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There was no evidence of mitosis or necrosis (Figure 4).
Immunohistochemical study of ELST. The tumor cells showed positive reactivity with pan-cytokeratin MNF116 (a) and chromogranin A (b) (immunostaining, 100x).
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Immunohistochemical studies were positive for CK MNF116 (cytokeratin wide spectrum:types 5, 6, 8, 17, and 19) and chromogranin A (Figure 5), with a Ki67 not being significant.
At 36-month follow-up a pure-tone audiometry identifies any worsening of hearing loss.
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Radiological and clinical evaluations at 36-month follow-up demonstrated no evidence of recurrence and a pure-tone audiometry identified any worsening of hearing loss (Figure 6).