By Jason Wasserman MD PhD FRCPC
March 6, 2023
A borderline Brenner tumour is a rare non-cancerous type of ovarian tumour. The tumour starts from the cells normally found on the outside surface of the ovary. Most are believed to develop from a benign Brenner tumour.
Most borderline Brenner tumours do not cause any symptoms until the tumour becomes very large. As a result, smaller tumours are usually found incidentally when the ovary is removed for other reasons.
A borderline Brenner tumour is a non-cancerous type of tumour that will not metastasize (spread) to other parts of the body. In contrast, a malignant Brenner tumour is a type of ovarian cancer made of very abnormal-looking cells that can metastasize to other parts of the body.
The diagnosis of borderline Brenner tumour can only be made after the tumour is removed and examined under the microscope by a pathologist.
When examined under the microscope, borderline Brenner is made up of tumour cells that look very similar to the cells normally found in the bladder. These cells are called transitional cells or urothelial cells. The tumour cells form long finger-like structures that pathologists describe as papillary. Mitotic figures (tumour cells dividing to create new tumour cells) may be found. In a borderline tumour, the cells do not show any evidence of invasion into the connective tissue.