Dermoid cysts are bizzarre tumours containing skin and other associated tissue, such as hair and skin glands and sebaceous material.
They are easily confused on ultrasound scan with haemorrhagic cysts
Dermoid cysts are usually treated by keyhole surgery
A second opinion with an expert performing the ultrasound scan is important to make sure of the diagnosis
Key information about Dermoid cysts
They are almost always benign
They are easily confused on ultrasound with haemorrhagic cysts
Important to get a second opinion on the ultrasound
Develop from eggs and have the potential to form any tissue in the body.
May occur at any age, but usually in the child bearing years
One in 500 dermoid cysts undergo a cancerous change
Cancerous form of dermoid is called an immature teratoma
About dermoid cysts
Dermoid cysts develop from egg cells in the ovary, and so have the potential to contain and tissue type in the whole body. The most common tissue type found is related to skin hence the name. This includes hair and teeth, both of which are derived from the skin. Other common tissues are thyroid tissue and neural tissue. Dermoid cysts slowly grow through the child-bearing years. The average is 30. A dermoid cyst will not go away without treatment. There is usually no urgency about treating a dermoid. They very rarely cause symptoms. They can be associated with twisting of the ovary when the blood supply to the ovary is cut off. This causes intense pain and is sometimes the way dermoid cysts are discovered. If this happens it is an emergency that needs to be treated immediately.
Diagnosis of ovarian cysts
Dermoid cysts are usually identified by an ultrasound scan. They are easily confused with haemorrhagic cysts which go will resolve spontaneously. Ultrasound scans are often incorrectly interpreted, because many people doing scans don’t have enough experience and expertise. An expert ultrasound scan will often give a very different diagnosis. Dermoid cysts do not release tumour markers, so there is no blood test for them. A repeat ultrasound scan a few weeks later will help differentiate a dermoid cyst from a haemorrhagic cyst as the latter will often resolve by themselves.
Treatment of a dermoid cyst
Benign dermoid cysts in young women should be treated by removal of the cyst only and not by oophorectomy. Removal of the whole ovary is not necessary. The cyst can be carefully separated from the rest of the ovary and the ovary then recovers. Removal of the dermoid cyst can usually be done by keyhole surgery.
Removal of a dermoid cyst is not an urgent operation. If a dermoid cyst is very small, the risks of complications discussed below are very low. The cyst may be managed conservatively, and tracked with a repeat ultrasound scan after several months.
Dangers of a dermoid cyst
A dermoid cyst can lead to ovarian torsion. This is where the ovary twists on its blood supply. The ovary becomes starved of oxygen and this causes severe pain. This is a medical emergency and urgent surgery is required. This is uncommon, and women with an asymptomatic dermoid cyst should not worry that torsion is likely. It should be considered in the management of a dermoid cyst.
A dermoid cyst may rupture. This is extremely uncommon and almost never happens.
The incidence of a dermoid cyst becoming a cancer is 0.2%. This is more common in older women with the average age of malignant transformation being found is 52 years. It also tends to occur in larger cysts with the average size of cysts with malignant transformation being over 10 cm. Clues to the possibility of malignant change are irregular solid areas in the cyst, increased blood flow, and elevated tumour markers including SCC and CA 19.9.
Patients with cancer in a dermoid cyst present with symptoms of a palpable abdominal mass, abdominal distension, and lower abdominal pain.