Histopathology of the Inner Ear in a Case With Recent Onset of Cogan's Syndrome: Evidence for Vasculitis.

The association of sensorineural hearing loss and vertigo with inflammatory eye disease, usually interstitial keratitis, has been called Cogan's syndrome. The pathogenesis of Cogan's syndrome is unknown, but it has been assumed to be an immune mediated disorder with vasculitis. The histopathology of the inner ear in Cogan's syndrome has been described in 6 case reports. Although common pathologic findings in these reports include degeneration of the auditory and vestibular neuroepithelium, endolymphatic hydrops, fibrosis, and new bone formation, direct pathologic evidence of a vasculitis has not been published. A possible reason for this failure to identify vasculitis was a substantial delay (range, 4-40 years) between the onset of symptoms and examination of the otopathology. In the current case report, the patient had both auditory and vestibular symptoms and interstitial keratitis with a time delay of only 2 to 4 weeks between symptoms and death. Evidence of a vasculitis as a possible underlying etiology included H&E histopathology and anti-CD45 immunostaining of vessels both in the auditory and vestibular systems, supporting the hypothesis of a vasculitis as a mechanism in this disorder.