Endometrioid carcinoma with a low-grade spindle cell component: a tumor resembling an adnexal tumor of probable Wolffian origin.

Endometrioid carcinoma is known to have many histopathologic variants, which may cause diagnostic difficulty. One rare variant resembles Wolffian adnexal tumor (female adnexal tumor of probable Wolffian origin). This pattern can produce a significant solid component within the tumor. Once the true endometrioid nature of the tumor is recognized, the tumor can appear deceptively high grade by International Federation of Gynecology and Obstetrics grading criteria, which take into account the percentage of the tumor showing solid growth. The English-language literature on this variant is scant, and its behavior is not well documented. We present a case of ovarian endometrioid carcinoma with a Wolffian adnexal tumor pattern that recurred 19 years after the original surgery; and the patient continues to remain well without evidence of disease 1 year following her second surgery, that is, 20 years of indolent behavior. This long clinical course shows evidence for low-grade behavior for this tumor.