What is the distribution of ciliated epithelium in the human middle ear and its potential role in the formation of cholesteatoma?
The paucity of ciliated epithelial cells on the medial side of the tympanic membrane and the lateral surface of the ossicles in the epitympanum in cases with cholesteatoma and/or chronic otitis media does not support the mucosal migration theory of cholesteatoma formation.
Background: A cholesteatoma is a non-neoplastic epithelial lesion that contains layers of keratin in a cavity lined by keratinizing squamous epithelium and subepithelial connective tissue. Although benign, it can cause serious complications by eroding nearby structures or precipitating infection. Surgical removal of the lesion is considered the only effective medical therapy. There are several theories on the etiopathogenesis of acquired cholesteatoma, including one based on the premise that a squamous pouch is drawn inward by traction exerted by the interaction of opposing ciliated epithelial surfaces of middle ear mucosa on the medial surface of the tympanic membrane and the lateral surface of the ossicles.
Study design: Comparative study of 73 human temporal bones.
Setting: Otopathology Laboratory in the Department of Otolaryngology, University of Minnesota, Minneapolis.
Synopsis: The temporal bones were separated into five groups: 1. cholesteatoma; 2. chronic otitis media without cholesteatoma (COM); 3. retraction pockets (RPs); 4. cystic fibrosis (CF); and 5. a control group with no middle ear disease. In the epitympanum: There were no differences in the number or distribution of ciliated cells between the pars tensa and pars flaccida of the tympanic membrane among the groups. The mean number of ciliated cells at the lateral epitympanum’s mucosal lining and the malleus and incus’s lateral surface were significantly reduced in bones with cholesteatoma.
There were fewer ciliated cells in the RP group compared with non-diseased ears; when present, they were usually located at the lateral wall of the epitympanum, not on the ossicles. In the tympanic membrane: The mean number of ciliated cells was decreased in the cholesteatoma compared to RP groups. In the protympanum: Ciliated cells were plentiful for all four conditions studied.
The mean number of ciliated cells in the lateral wall of the protympanic space was decreased in the group with cholesteatoma and COM compared to RP, CF, and control groups. Some ciliated cells were found at the tympanic membrane’s anterior annulus and at the posterior portion of the handle of the malleus, in contact with the tympanic membrane. The epithelium covering the ossicles’ lateral face at the epitympanum and at the medial surface of the tympanic membrane consisted of flat simple squamous epithelium.
Citation: Pauna HF, Monsanto RC, Schachern P, et al. Evidence against the mucosal traction theory in cholesteatoma. Laryngoscope. 2018;128:1663–1667.