The Tensor Tympani Tendon: A Hypothetical Site of Origin of Congenital Cholesteatoma

Abstract

Multiple theories have been discussed about the etiopathogenesis of congenital middle ear cholesteatoma (CMEC) and its specific site of origin. The intraoperative identification of the precise location of the keratinous mass is important to guarantee its complete removal, in order to reduce the risk of recurrence. This study proposes the tensor tympani tendon (TTT) as a possible site of origin of CMEC. All CMECs treated between 2013 and 2019 were reviewed. Only Potsic stage I lesions were included. Preoperative radiologic images were compared to intraoperative findings. Three removed TTT were sent for histologic evaluation. Seven patients were included (M:F = 3:4). Preoperative CT images were classified as type A in 2 cases (28.6%) and type B in 5 cases (71.4%). At intraoperative evaluation all CMEC sacs were found pedunculated on the TTT. The histologic examinations confirmed the connection between the cholesteatomatous sac and the TTT. According to the correlation of imaging, intraoperative findings and histology, we proposed that the TTT could be the primary site from which CMEC originates.

Keywords: Cochleariform process; Congenital cholesteatoma; Histology; Pediatric ear surgery; Tensor tympani tendon.

Fig. 1

a–d Endoscopic intraoperative appearance of four stage I congenital middle ear cholesteatomas and relevant surgical landmarks. cc congenital cholesteatoma, hm handle of the malleus, i incus, fn facial nerve, s stapes, rw round window

Fig. 2

Microscopic intraoperative view of congenital middle ear cholesteatoma, before removal. a relationship between the cholesteatomatous sac and the tensor tympani tendon; b cutting the tensor tympani tendon before removing the cholesteatoma

Fig. 3

Comparison between preoperative temporal bone computed tomography of type I B congenital cholesteatoma (a) and intraoperative endoscopic view after elevation of the tympano-meatal flap (b). cp cochleariform process, tt tensor tympani tendon

Fig. 4

a Histologic evaluation of congenital middle ear cholesteatoma (CMEC). a Keratinizing, stratified epithelium lining CMEC (hematoxylin–eosin staining—H&E, 40×); b CMEC surrounded by fibrous tissue including a thin layer of cuboidal cells (H&E, 10×); c Cuboidal cell surrounding tendon (MNF-116); d cuboidal cells connecting to the wall of CMEC (MNF-116)

Fig. 5

A 200 × hematoxylin–eosin staining showing the close relationship between the tensor tympani tendon and the congenital middle ear cholesteatoma