by Jason Wasserman MD PhD FRCPC
May 9, 2022

What is endometriosis?

Endometriosis is a non-cancerous condition that occurs when tissue that is normally found in a part of the body called the endometrium starts growing outside the endometrium.

What parts of the body are commonly affected by endometriosis?

Endometriosis commonly involves the ovaries, fallopian tubes, outside surface of the uterus, posterior cul-de-sac (space between the uterus and the rectum), anterior cul-de-sac (space between the uterus and the bladder), and appendix. However, endometriosis can develop anywhere in the body.

What are the symptoms of endometriosis?

Many women with endometriosis experience pain and the pain may be worst at the same time as their normal menstrual period. Over time, this condition can cause large blood-filled cysts to develop. These cysts can become very large and may eventually need to be removed.

What does endometriosis look like under the microscope?

When examined under the microscope, endometriosis is made up of glands and stroma. that are normally found in a part of the body called the endometrium. Blood or hemosiderin (a product of the breakdown of old blood) may also be seen.

Does endometriosis increase the risk of developing cancer?

Although endometriosis is considered a non-cancerous condition, it is associated with an increased risk of cancer. In particular, when this condition involves the ovary, it is believed to provide the ‘seed’ for the development of clear cell carcinoma and endometrioid carcinoma. While many women have endometriosis, very few will develop either of these cancers and so the risk is actually very low.

Other helpful resources

Office on Women’s Health

Endometriosis Foundation of America

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