Histopathology of otosclerosis.

This histopathologic review illustrates that otosclerosis is a very pleomorphic bone dyscrasia. It may fix the stapes by a tiny bridge of abnormal bone or may totally obliterate it. It may spread to the cochlea to produce either a sensorineural loss of varying degree or deafness. Lesions may be sclerotic, spongiotic, or fibrous but usually comprise all these histologic types. This diversity of size and anatomic distribution coincides with the variable types of hearing loss, from a mild conductive deficit to a total loss. In spite of more than a century of investigation of otosclerosis, an etiologic agent other than heredity has not been established.