4.1.1 Tympanosclerosis
Tympanosclerosis, a common sequela of chronic otitis media, is characterized by hyaline degeneration and the deposition of calcareous plaques in the connective tissue of the fibrous layer of the tympanic membrane and/or middle ear submucosa; it may result in local bone metaplasia during its late stages of development.5 As EC-LSC is essentially a form of heterotopic ossification; the resultant osseous tissue features an external morphology and texture similar to that of normal bone but – as revealed by pathological examination – also possesses the pathological characteristics of internal osseous structures and lacunae. Table 3 shows the differences between tympanosclerosis and EC-LSC. In some cases, EC-LSC may co-exist with tympanosclerosis. This is clearly demonstrated by the presence of concomitant EC-LSC and tympanosclerosis in three of the seven patients investigated in this study. The co-presentation posed a significant challenge during surgical operations.