Mucinous cystadenofibroma of the ovary

What is mucinous cystadenofibroma?

A mucinous cystadenofibroma is a non-cancerous type of ovarian tumour.  While these tumours are non-cancerous, they can grow to be very large in size and can cause significant symptoms for many patients.

The ovary

The ovaries are part of the female reproductive tract. The ovaries are small organs that are located at the ends of the fallopian tubes and are attached to the uterus by the ovarian ligaments. The outer surface of the ovaries is lined by specialized epithelial cells that form a barrier called an epithelium. The epithelial cells on the surface of the ovary are also called the capsular surface. The tissue below the epithelium is called the stroma.

Gynecological tract

How do pathologists make this diagnosis?

For most women, the diagnosis of mucinous cystadenofibroma 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.

Your surgeon may 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 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 filled with fluid. Pathologists call these spaces cysts. The spaces are separated by thick walls or solid areas filled with stromal cells.

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 that produces a thick, gelatinous fluid called mucin. The mucin fills the inside of the tumour. Tumours will more solid areas may contain less mucin.

Histologic type

There are two types of mucinous cystadenofibroma, endocervical and intestinal. The histologic type can only be determined after a tissue sample has been examined under the microscope by a pathologist. While the intestinal type is more common than the endocervical type, there is no difference in prognosis between these two histologic types.

  1. Endocervical – In this type of tumour, the cells in the epithelium look similar to the cells that line the endocervical canal (the canal that leads from the cervix into the uterus).
  2. Intestinal – In this type of tumour the cells in the epithelium look similar to the cells that line the digestive (intestinal) tract.  The intestinal type is more common than the endocervical type.
Atypia

Atypia is a word pathologists use to describe cells that look different from cells normally found in that location. Most mucinous cystadenofibromas do not contain any atypical cells. A tumour with atypical cells is sometimes called a mucinous tumour with focal atypia.

Examination of the tumour surface

Most mucinous cystadenofibromas 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.

Epithelial proliferation

The inner surface of most mucinous cystadenofibromas are lined by a flat single layer of cells. Some tumours, however, have small growths or proliferations of the mucinous epithelium that make them look more complex when examined under the microscope.  If the tumour has areas with these features, it may be called a mucinous tumour with focal epithelial proliferation.

by Emily Goebel, MD FRCPC, updated December 30, 2020
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