Human endometrium and endometriotic tissue obtained simultaneously: a comparative histological study

A comparative study on the histological appearance of endometrium and endometriotic tissue obtained simultaneously has been performed. In all, 47 endometriotic samples from 28 patients were examined. In 15 cases, samples from more than one endometriotic lesion were included. The endometriotic tissue had developed a distinctive menstrual phase pattern in 23 patients (82%). In 16 of these patients (70%), the phase pattern was found to be synchronous (+/- 3 days) in the two tissue types. In seven cases (30%), it varied inconsistently as compared with the endometrial phase. In the remaining five cases (18%), no menstrual phase pattern was found in the endometriotic specimens in spite of a well-defined phase in the endometrium. When biopsy specimens from different endometriotic lesions in the same patient showed a menstrual phase pattern, the phase did not differ significantly among the specimens. Although a menstrual phase pattern could be recognized in the endometriotic tissue samples in most cases, a considerable variability in glandular and epithelial cell morphology was frequently found.