Analysis of the clonality of ectopic glands in peritoneal endometriosis using laser microdissection

OBJECTIVE: To investigate the clonality of ectopic gland cells in peritoneal endometriosis. DESIGN: Prospective study. University hospital. PATIENT(S): Seventeen women with surgically diagnosed endometriosis. INTERVENTION(S): Samples of peritoneal endometriotic lesions were obtained from patients during laparoscopic surgery. MAIN OUTCOME MEASURE(S): Clonality analysis used the laser microdissection technique, a phosphoglycerate kinase (PGK) gene polymorphism assay, and an androgen receptor (AR) gene polymorphism assay after digestion of the DNA with methylation-sensitive endonuclease. RESULT(S): Each ectopic gland of the peritoneal endometriotic lesion showed a monoclonal pattern in both the PGK gene and AR gene assays, but the methylation pattern of the PGK gene and/or AR gene was divergent among adjacent glands in the lesion. These data indicate that the peritoneal endometriotic lesions are multicellular in origin, although individual glands of the lesion are derived from single precursor cells. CONCLUSION(S): The colored peritoneal endometriotic lesion in the present study was multicellular in origin. Peritoneal endometriotic lesions may thus be initiated by transplantation of a cluster of eutopic endometrial tissues into the pelvis.