Endometrioid adenocarcinoma with squamous differentiation arising from ureteral endometriosis in a patient with no history of gonadal endometriosis

This is the second case of a malignancy arising in endometriosis presenting as an obstructive ureteral mass and the first case of a patient with this condition whose endometriosis is not consistent with a gonadal origin. An analysis of the case and related literature is presented together with the discussion of possible pathogenetic mechanisms.