Collision tumors represent a coexistence of two adjacent but histologically distinct tumors without histologic admixture in an organ.

Ovarian fibroma is the most common benign stromal tumor. Serous tumors of the ovary are the most common of epithelial tumors. However, a collision between them is a rare pathology mimicking a malignant tumor. We report a 63-year-old woman with sparse postmenopausal bleeding. Ultrasound examination of organs in a small pelvis rounded right ovary formation with hypo and hyperdense sections. Paraclinical: CA125 slightly increased. Histological: collision between two benign ovarian tumors imitating carcinoma.