Incidental pregnancy luteoma associated with ectopic tubo-ovarian pregnancy: evidence in favor of origin from theca interna of an atretic follicle.

An incidental pregnancy luteoma was identified microscopically in an ovary submitted for ruptured ectopic tubo-ovarian pregnancy. The lesion consisted of a localized, non-encapsulated proliferation of thecal cells in the wall of an atretic follicle and had all the pathologic features of the typical late pregnancy luteoma. This finding is presented to support the origin of the pregnancy luteoma from the theca interna of atretic follicles.