MONOCLONAL ORIGIN OF ENDOMETRIOTIC CYSTS

Endometriosis-endometrial tissue in an ectopic site outside the uterus -is one of the most common gynecologic disorders. The pathogenesis of this disease is controversial; the two major theories implicate either metaplasia or metastatic spread. In the ovary, endometriosis sometime s appears as endometriotic cysts. Occasionally, malignant tumors devel op within these cysts, which therefore have been suggested to carry a neoplastic potential. We have investigated the clonal origin of five s uch ovarian cysts by a recombinant DNA X-chromosome inactivation techn ique. Three of the endometriotic cysts showed a monoclonal X-chromosom e inactivation pattern, ie the cell populations of those cysts were ea ch derived from one cell, whereas the remaining two cysts had polyclon al inactivation patterns. These findings suggest that endometriotic cy sts can, in at least some cases, be regarded as neoplasic.