Müllerianosis

Müllerianosis may be defined as an organoid\n\t\t\t\t structure of embryonic origin; a choristoma composed of\n\t\t\t\t müllerian rests - normal endometrium, normal\n\t\t\t\t endosalpinx, and normal endocervix - singly or in\n\t\t\t\t combination, incorporated within other normal organs\n\t\t\t\t during organogenesis. A choristoma is a mass of\n\t\t\t\t histologically normal tissue that is “not normally found\n\t\t\t\t in the organ or structure in which it is located”\n\t\t\t\t (Choristoma, 2006). Müllerian choristomas are a subset\n\t\t\t\t of non-müllerian choristomas found throughout the\n\t\t\t\t body.\n\t\t\t\t Histologically, endometrial-müllerianosis and\n\t\t\t\t endometriosis are both composed of endometrial glands\n\t\t\t\t and stroma, but there the similarity ends. Their\n\t\t\t\t pathogenesis is different. Sampson faced the same\n\t\t\t\t difficulty with pathogenesis and nomenclature when he\n\t\t\t\t wrote: “The nomenclature of misplaced endometrial or\n\t\t\t\t müllerian lesions is a difficult one to decide upon.” “The\n\t\t\t\t term müllerian would be inclusive and correct, but\n\t\t\t\t unfortunately it suggests an embryonic origin.” Sampson\n\t\t\t\t then divided “misplaced endometrial or müllerian tissue”\n\t\t\t\t into “four or possibly five groups, according to the\n\t\t\t\t manner in which this tissue reached its ectopic location”\n\t\t\t\t (Sampson, 1925).\n\t\t\t\t Sampson’s classification of heterotopic or misplaced\n\t\t\t\t endometrial tissue is based on pathogenesis: 1) “direct or\n\t\t\t\t primary endometriosis” [adenomyosis]; “a similar\n\t\t\t\t condition occurs in the wall of the tube from its invasion\n\t\t\t\t by the tubal mucosa” [endosalpingiosis]; 2) “peritoneal\n\t\t\t\t or implantation endometriosis;” 3) “transplantation\n\t\t\t\t endometriosis;” 4) “metastatic endometriosis;” and 5)\n\t\t\t\t “developmentally misplaced endometrial tissue. (I admit\n\t\t\t\t the possibility of such a condition, but have never been\n\t\t\t\t able to appreciate it.)” (Sampson, 1925). It is precisely\n\t\t\t\t this condition “developmentally misplaced endometrial\n\t\t\t\t tissue,” [müllerianosis] that is the subject of this review.