Müllerianosis

Müllerianosis may be defined as an organoid \nstructure of embryonic origin; a choristoma composed of \nmüllerian rests - normal endometrium, normal \nendosalpinx, and normal endocervix - singly or in \ncombination, incorporated within other normal organs \nduring organogenesis. A choristoma is a mass of \nhistologically normal tissue that is “not normally found \nin the organ or structure in which it is located” \n(Choristoma, 2006). Müllerian choristomas are a subset \nof non-müllerian choristomas found throughout the \nbody. \nHistologically, endometrial-müllerianosis and \nendometriosis are both composed of endometrial glands \nand stroma, but there the similarity ends. Their \npathogenesis is different. Sampson faced the same \ndifficulty with pathogenesis and nomenclature when he \nwrote: “The nomenclature of misplaced endometrial or \nmüllerian lesions is a difficult one to decide upon.” “The \nterm müllerian would be inclusive and correct, but \nunfortunately it suggests an embryonic origin.” Sampson \nthen divided “misplaced endometrial or müllerian tissue” \ninto “four or possibly five groups, according to the \nmanner in which this tissue reached its ectopic location” \n(Sampson, 1925). \nSampson’s classification of heterotopic or misplaced \nendometrial tissue is based on pathogenesis: 1) “direct or \nprimary endometriosis” [adenomyosis]; “a similar \ncondition occurs in the wall of the tube from its invasion \nby the tubal mucosa” [endosalpingiosis]; 2) “peritoneal \nor implantation endometriosis;” 3) “transplantation \nendometriosis;” 4) “metastatic endometriosis;” and 5) \n“developmentally misplaced endometrial tissue. (I admit \nthe possibility of such a condition, but have never been \nable to appreciate it.)” (Sampson, 1925). It is precisely \nthis condition “developmentally misplaced endometrial \ntissue,” [müllerianosis] that is the subject of this review.