Brenner Tumor of the Ovary: CT and MRI Findings

Brenner tumors arise from ovarian surface epithelium or coelomic mesothelium composed of transitional cells with dense stroma. They constitute about 2–3% of ovarian tumors and are mostly benign and rarely malignant. About 90 – 95% are incidental as solid or mixed and rarely cystic tumors. They occur throughout the lifespan, with the majority of patients presenting between age group 30 to 63 years. Majority of the Brenner tumors are asymptomatic but abnormal bleeding is the most common presentation followed by non specific pain, or symptoms due to mass effect. They may vary in size, often associated with other epithelial tumors with most measuring <5 cm in diameter. Extensive calcification may occur in the stroma as a degenerative change in Brenner tumors. Ultrasound and CT may show Brenner tumors, but both techniques are limited in their non specific imaging appearances. On US, they appear as solid hypoechoic masses often with calcification. CT shows a solid or a mixed solid-cystic tumor, often with calcifications in the solid parts of the tumor. These calcifications are amorphous in appearance. The solid components of these masses are mildly or moderately enhanced. MRI show a T1-and T2-weighted hypointense solid component containing dense fibrous stroma similar to fibroma which is a characteristic feature, while cystic may show fluid sensitive signal intensity on T2 weighted sequence. Solid component usually enhances on contrast administration. The differential diagnosis for solid neoplasms includes fibroma, fibrothecoma, pedunculated leiomyoma, and metastasis. However, lack of metastasis, lymph nodes, invasion of surrounding structures differentiates them from malignant ovarian tumor despite large size. The gross appearance of borderline or malignant Brenner tumors differs from that of benign tumors. The borderline or malignant tumors are mostly cystic with solid papillary projections; while benign have characteristic fibrous tissue signal intensity with mild, patchy enhancement after intravenous contrast administration. Surgical resection is often curative even with malignant Brenner tumor. In our case, exploratory laporotomy with resection of the pelvic mass, total hysterectomy and right oopherectomy was performed. Final surgical pathology revealed a Brenner tumor.