[Histopathological studies on paranasal mucosa from patients treated with erythromycin]

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.