Uterine Adenosarcoma Originating in Adenomyosis: Report of an Extremely Rare Phenomenon and Review of Published Literature.

Müllerian adenosarcoma is an uncommon biphasic malignant tumor most often occurring in the uterine corpus and derived from native surface endometrium. We report a case of intramural uterine adenosarcoma arising in association with adenomyosis, in the absence of tumor involving the surface endometrium. This is an extremely rare phenomenon, with only 8 other published cases of uterine corpus adenosarcoma in the absence of surface endometrial involvement, 5 originating in adenomyosis and 3 in adenomyomas. We review these cases. The current FIGO staging system for uterine adenosarcoma assumes origin from the surface endometrium and does not address the rare occurrence of intramural tumors without a surface endometrial component. Such tumors are problematic to stage and could potentially be overtreated, particularly if there is deep myometrial involvement.