Endometriosis: Fluorescence of experimental endometriosis in rabbits, using tamoxifen—eosin association

A major problem with endometriosis is the detection of microscopic and atypical lesions. An incomplete surgical eradication may lead to recurrence of the disease. This study aimed to investigate the diagnostic improvement of endometriosis by the use of tamoxifen-eosin induced fluorescence. The experimental study was performed on surgically induced endometriosis in the rabbit. Endometriosis was induced by grafting endometrium onto the broad ligament in 10 rabbits. After 5 weeks, the fluorescence of excised endometriosis was studied after systemic injection of tamoxifen and local application of eosin. Healthy peritoneal samples served as controls. The fluorescence of endometriotic foci was also compared with (n=5) or without (n=5) tamoxifen. Fluorescence excitation was carried out using a 150 W filtered lamp connected to an optical fibre. Fluorescence emission was measured using an optical fibre connected to a spectrofluorometer. Spectral analysis showed a specific fluorescence of endometriosis 72 h after systemic injection of tamoxifen and eosin application. This result is explained by binding to oestrogen receptors of tamoxifen which was protonized to form an ionic pair with eosin. Histological study of samples from the graft of endometrial tissue showed that experimental endometriosis had developed in eight out of the 10 rabbits. However, the fluorescence was not significantly different among the 10 rabbits. This observation was in accordance with previous studies in which endometriosis was confirmed by routine histological techniques or electron microscopy in 70-80% of cases. Consequently, the fluorescence of the two samples which did not present histological evidence of endometriosis indicates the presence of microscopic endometriotic foci. This observation suggests that the diagnosis of endometriosis by the use of tamoxifen - eosin induced fluorescence improves the sensitivity of detection. Identification of microscopic endometriosis will be carefully studied and the consequences of an early identification, which could lead to excessive surgical treatment of this disease, will be evaluated