Borderline Brenner tumor with abnormally high serum level of carbohydrate antigen 199: a rare case report and literature review.

Ovarian Brenner tumor with abnormally increased serum carbohydrate antigen 19-9 (CA19-9) level is extremely rare. A 70-year-old woman with abnormally elevated serum CA199 (1289 U/ml) found in routine physical examination. Pelvic CT and MRI scan revealed a large mass with large patches of calcification in the right adnexal area, and the patient achieved total hysterectomy and bilateral adnexectomy. Grossly, the right ovary had a solid enlargement of about 7.0 cm × 6.0 cm × 5.0 cm with irregular nodules and smooth surface and the cut surface of the mass showed that the tumor is cystic and solid. Microscopically, the tumor showed a background of fibrous tissue hyperplasia with nested and adenoid cell clusters with uniform cell size and clear boundaries. The cells were translucent with eosinophilic cytoplasm and calcification. Immunohistochemical staining showed CK7, CA125, and P63 presented diffusely strongly positive staining, while negativity for CK20, GATA3, AR, P53, and CgA. Ki-67 showed weak positive staining, about 1%. The serum CA199 level decreased significantly on the 5th day after surgery. Postoperative pathology and immunohistochemistry confirmed borderline Brenner tumor. This is the first to report a case of borderline Brenner tumor with an abnormally high serum level of CA199 before surgery. In clinical practice, the possibility of ovarian Brenner tumor should be considered when abnormal elevation of serum CA199 level cannot be reasonably explained.