Pathology of Granular Myringitis: A Light and Electron Microscopic Study

Background: Granular myringitis (GM) is characterized by the development of granulation tissue over the tympanic membrane and adjacent canal. The condition can be misdiagnosed as chronic otitis media (COM) complicated with granulations, since intermittent purulent discharge is the commonest symptom in both disorders. Aim of Study: To microscopically examine the granulation found in GM and those due to COM to find some differentiating criteria of each condition. Patients and Methods: A total of 13 cases of GM, 10 of which were diagnosed clinically as GM from the start. The other 3 cases were suspected to have COM with granulations and tympanoplasty was proposed for their management. However, during the operation, they proved to be GM cases, as evidenced by the presence of normal middle ear mucosa with the granulations located only at the edges of the perforations. In these cases, the trimmed edge of the perforation with the granulation was taken as our biopsy. The study also included 10 patients, diagnosed as COM with granulations, as evidenced by the presence of marginal drum perforation with granulations canal. Pure-tone audiometry showed an airbone gap, and X-ray examination showed abnormal mastoid air cells. A biopsy was taken from the granulation during surgical management of such cases. A histological study was performed on 2 normal tympanic membranes (obtained from the temporal bone laboratory) as a control group. Results: Granulation was found in both GM and COM with subtle differences. During our electron microscopic examination of the specimens from GM intracellular inclusion bodies were detected frequently. This suggests that viruses may be etiological factor. Conclusions: Components of granulation tissue of both GM and middle ear granulations are almost similar. The presence of some subtle differences is not sufficient to rely on histological examination for diagnosis. The presence of intracellular inclusion bodies in many specimens suggests that viruses may be an etiologic factor in GM and can explain the frequent recurrence characterizing this disease.