Low-dose and long-term administration of
erythromycin (EM
therapy) has been reported to be very effective for patients with intractable chronic
sinusitis including sinobronchial syndrome. However, we sometimes encounter patients whose
sinusitis is extremely resistant to EM
therapy. Therefore, the present study was carried out to determine the correlation between the clinical efficacy of EM
therapy and the histopathological features of the ethmoidal mucosa and
nasal polyps of patients treated with
erythromycin. Patients with significant lymphocytic infiltration in the submucosal area responded well to EM
therapy. Furthermore, patients with neutrophilic infiltration within and beneath the ciliary epithelium tended to show improvement with this
therapy. On the other hand, EM
therapy was minimally effective in patients whose subepithelial layer showed marked eosinophilic infiltration. In patients showing excellent and good clinical results, histological changes in the paranasal mucosa after
therapy were as follows: a decrease in the number of inflammatory cells, reduced interstitial
edema, increased
fibrosis and normalization of the secretory glands. From these results, we conclude that
erythromycin may suppress chronic
inflammation except for an
allergic reaction characterized by marked eosinophilic infiltration.