This article was reviewed and updated on July 29, 2019
by Jason Wasserman, MD PhD FRCPC
Serous cystadenoma is a very common non-cancerous ovarian tumour.
These tumours can grow to become very large which can cause pain.
The diagnosis of a serous cystadenoma is only made after the tumour has been removed and sent to a pathologist for examination.
The normal ovary and fallopian tube
The ovaries are part of the female reproductive tract. They are small organs that are attached to the uterus by the fallopian tubes. The outer surface of the ovaries are lined by a thin layer of specialized tissue called an epithelium that forms a barrier around the outside of the ovary. The organs inside the abdomen are lined by a thin layer of tissue called the peritoneum that is made up of similar cells. The ovaries also contain large cells called eggs. The tissue below the epithelium is called stroma.
What is a serous cystadenoma?
A serous cystadenoma is a very common non-cancerous (benign) tumour that develops from the cells on the surface of the ovary. While these tumours are non-cancerous, they can grow to be very large in size and as a result can cause significant symptoms for many patients.
How do pathologists make this diagnosis?
Most tumours are similar in look and feel to a balloon filled with fluid. The inside of the tumour may be one large space or many small spaces spaces filled with fluid. Pathologists call these spaces cysts.
When the tumour is examined under the microscope, the tissue on the inside of the cysts is made up of an abnormal type of epithelium made up of serous cells. These cells produce a fluid that fills the inside of the tumour.
Some tumours will have thicker walls or solid areas in the center of the tumour. These tumours contain more cells and less fluid and are called serous adenofibromas. However, they are still non-cancerous.
For most women, the diagnosis of serous cystadenoma is only made when the entire tumour has been surgically removed and sent to a pathologist for examination. The fallopian tube and uterus may be removed at the same time.
In some situations, the surgeon will request an intraoperative or frozen section consultation from your pathologist. The diagnosis made by your pathologist during the intraoperative consultation can change the type of surgery performed or the treatment offered after the surgery is completed.
Most serous cystadenomas have a smooth outer surface. Any solid areas on the surface will be examined closely under the microscope to make sure they do not contain any abnormal cells.
The cells in a serous cystadenoma usually look very similar to the normal cells that line the outside of the ovary. However, some tumours may have cells that look different. Atypical cells are tumour cells that are larger or darker than normal cells.
Why is this important? Although they are abnormal looking, atypical cells are not cancer cells.
The inside of most serous cystadenomas are lined by a flat single layer of cells. When examined under the microscope, however, some tumours have small growths that look like like little fingers. Pathologists describe these small growths as papillary.
Why is this important? Serous cystadenomas with papillary growths are still non-cancerous.