Mast cells in chronic inflammation of the middle ear mucosa

The number, distribution and degranulation frequency of mast cells have been studied in the middle ear mucosa biopsies of patients with chronic otitis media.

The pathohistological analysis has been performed on 115 biopsy specimens, taken intraoperatively from the different regions of the middle ear cleft in 27 patients with chronic otitis media and in 15 children with otomastoiditis which occurred during the treatment of secretory otitis media. Mast cells were identified on the basis of metachromatic staining for histamine and heparin granules.

The findings of this study confirm that the number of mast cells is increased in all areas of middle ear cleft in chronic inflammation of the middle ear mucosa. Mast cells were identified in 108 out of 115 analysed samples. In chronic otitis media of atticoantral and tubotympanic type mast cells were present in 91.5% of samples, the cells with heparin granules were present in 62.2% and degranulation frequency was 37.8%. In secretory otitis media 33 mucosal samples were analysed and all samples contained mast cells with predominance of histamine granules and with de granulation frequency of 81.8%.

These findings indicate that mast cells have complex function in pathophysiology of chronic inflammation of the middle ear mucosa: it may take part in amplification of inflammation as well as in its limitation. Further studies are needed to clarify the role of histamine and heparin in chronic inflammatory reactions of the middle ear mucosa.