Unusual Collision Tumor of Ovary: Endometrioid Adenocarcinoma and Teratoma

Introduction Collision tumors represent the coexistence of 2 histologically distinct tumors adjacent to one another in the same organ, without admixture of the components of the tumors. Although uncommon, hey have been described in almost all major organs, with a variety of omponent pathologic features. The majority are diagnosed postopratively after histologic examination. The origin of these tumors has een debated. It is proposed that collision tumors could arise from 2 ifferent cell lines growing at the same time side by side or a chance ccurrence of 2 tumors in the same organ. The other commonly held iew is the origin from a common precursor pluripotent stem cell. ancer is considered to be a disease of the stem cell, and given the lasticity of the stem cell to differentiate this theory is made more lausible. Ovarian collision tumors are rare. We report a case of collision tumor of the ovary composed of teratoma and endometrioid adenocarcinoma.