PMC6652060_01
(a) A red mass was observed under the anterior quadrant of the tympanic membrane. (b) Pure-tone audiometry. The black and gray lines show the preoperative and postoperative hearing levels, respectively, in the right ear. After the surgery, the hearing level was not reduced and a normal hearing level was preserved. (c, d) A high-resolution computed tomography scan ((c) axial view and (d) coronal view) shows a mass on the promontory. (e) Postoperative tympanic membrane.
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A reddish mass was observed through the anterior quadrant of her right tympanic membrane (Figure 1(a)). Her pure-tone audiometry showed a normal hearing level on the right side (Figure 1(b)). A computed tomography scan revealed a small mass in the mesotympanum (Figures 1(c) and 1(d)). Postoperative pure-tone audiometry demonstrated a normal hearing level (Figure 1(d)). No recurrence was observed 3 years after the surgery (Figure 1(e)).
Findings seen during transcanal endoscopic ear surgery. The reddish tumor (asterisk) was located on the promontory. The tumor feeder was identified as the inferior tympanic artery (arrow).
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The skin of the external ear canal was incised, and the tympanomeatal flap was elevated, concentrating on not damaging the surface of the tumor to prevent bleeding (Figure 2). The vascular supply to the tumor was from the inferior tympanic artery (Figure 2).
Histopathology. Hematoxylin-eosin staining: (a) reticular vascular-rich round tumor (x40) and (b) round tumor cells were aggregated showing ribbon-like (arrow) and island-like (arrow head) formations in vascular spaces (vascular spaces were lined by endothelial cells (x200)). Immunohistochemical staining (x400): (c) alpha-smooth muscle actin (alpha-SMA) was negative, (d) synaptophysin was positive, (e) S-100 protein was positive on sustentacular cells, (f) cytokeratin AE1/AE3 was negative, and (g) neuron-specific enolase (NSE) was positive.
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Pathological findings (Figure 3) confirmed a reticular vascular-rich tumor (approximately 5 x 5 mm) comprising round tumor cells aggregating as ribbon-like and island-like formations in vascular spaces.