Estriol induced squamous metaplasia on the nasal mucosa in patients with hereditary hemorrhagic telangiectasia.

Background: The aim of this study was to evaluate by light and electron microscopy the effect of topical estriol on the nasal mucosa in patients with hereditary hemorrhagic telangiectasia (HHT).

Methods: Twelve patients were instructed to apply twice daily 0.1% estriol as a nose ointment over a period of 12 months. Written consent was obtained from each patient, allowing biopsy specimens of the nasal mucosa to be taken prior to and 3, 6 and 12 months after estriol application.

Results: Metaplastic change of the nasal mucosa was observed 6 months after topical estriol application. The former ciliated columnar epithelium changed into a keratinizing squamous epithelium. The effect was reversible after discontinuation of estriol application.

Conclusions: For the first time, we could outline the effect of topical estriol on the nasal mucosa. These histomorphological findings, and the fact that estriol is a low-potency metabolite of estradiol, make estriol a valuable agent in the treatment of HHT patients.