Mastocytes in chronic inflammation of middle ear mucosa

Background: Pathohistological studies have shown that in secretory otitis media an increased number of mast cells have been found in mucosa of the middle ear and an increased level of histamine in the cavity of the middle ear. The aim of this study was to analyse the distribution and functional state of mast cells in middle ear mucosa biopsies in patients with chronic otitis media.

Methods: The pathohistological analysis was performed on 118 biopsy specimens of mucosa of the middle ear. The samples were taken intraoperatively from 39 patients during the surgical treatment of chronic otitis media with and without cholesteatoma and otomastoiditis. The specimens were taken from mastoid, attic space, promantory and protympanon. All biopsy specimens were prepared for hematoxylin-eozin staining and were identified with PAS method and Lennert Giemsa histamine granules. The Alcian blue-Safranin method was used to identify heparin granules in mast cells. By using the semiquantitative method, distribution of mast cells was marked as rare (+), numerous (+2) and high (+3). Also the number of degranulated cells was identified (Tables 1, 2).

Conclusions: The analyses of biopsy specimens of mucosa of the middle ear in chronic otitis media showed that cells were present in all areas of mucosa in a considerably higher number (Table 1). Degranulated cells were frequently found in biopsy specimens of otomastoiditis and contained predominately histamine granules; thus specimens taken from chronic otitis media, with and without cholesteatoma, showed mast cells with heparin granules with low rate degranulation. Pathophysiological examinations of the role of mast cells in the mechanism of chronic inflammation have shown that mast cells display through mediators the biphasic effect. They can participate in the process of deterioration of inflammation, whereby the released mediators cause the processes of tissue destruction, and can stimulate the process of tissue repair. Heparin accelerates the healing process of tympanic membrane perforation, stimulates the proliferation of endothelial cells and supports angiogenesis in the lamina propria of the tympanic membrane. Further studies are needed to clarify the role of histamine and heparin in the pathophysiology of chronic inflammation in chronic otitis media.