Moles and Malignant Melanoma

The aim of this leaflet

This leaflet is designed to help you understand more about the evolution of moles (melanocytic nevi) and malignant melanoma (dark skin cancer / cancerous mole) during pregnancy. It tells you what these conditions are, what causes them, what can be done about them, and where you can find more information about them. 


What are moles?

Moles (melanocytic nevi) are benign (not-cancer) spots which are usually dark brown in colour, but can also be skin coloured and can have different shapes and sizes. They can be raised on the skin or may contain dark hairs; the number varies between 10 and >100 moles on a person. This number may change throughout life. Moles are also called “beauty marks”. Sometimes they are congenital (present at birth) but mostly they are acquired (come up later). In the majority of cases they are harmless, except for some rare cases when they can become cancerous.

What causes moles?

Genes (hereditary) play an important role in the formation of moles. In the case of acquired moles, sun light exposure or any artificial sources of ultraviolet light exposure (sun beds or tanning lamps) also contribute. 

What is the appearance of moles in pregnancy?
What to look for?

During pregnancy, moles can get darker and larger, particularly on the belly and breasts. These benign changes are usually symmetric. Therefore, any asymmetric change in size, shape or colour should be examined by your dermatologist.
A dermatoscopic evaluation (examination moles with a hand-held microscope) of the mole during pregnancy may reveal some modifications in the structure which will often completely resolve after delivery.



What is malignant melanoma?

Malignant melanoma is a skin cancer originating from melanocytes (the skin cells that produce melanin - the dark pigment) arising on normal skin or from a pre-existing mole. The condition is curable if the malignant process is limited to the surface of the skin and treated early. If not treated, melanoma may grow down into deeper layers of the skin and may finally spread throughout the body (metastasis).

What causes malignant melanoma?

Again, genetics and sun exposure are major risk factors for melanoma. The risk of melanoma is increased in people with a personal (and family) history of melanoma, fair skin,  many freckles, and red hair as well as excessive sun exposure, in particular blistering sun burns in childhood and excessive ultraviolet radiation such as  intense irregular sun exposure,  and sun beds.
Risks factors for developing a melanoma:

  • fair skin, high density of freckles, red hair
  • more than 50 moles
  • the presence of more than 5 atypical moles (moles with irregular shape and colour)
  • a history of sunburns, especially with blistering
  • family history of melanoma 
What is the appearance of melanoma in pregnancy?
What to look for?

The appearance of melanoma in pregnancy is identical to that in non-pregnant women. Any spot that changes in colour, size, or shape or bleeds, becomes an open wound (ulceration), painful, or itchy must be examined by a dermatologist.
A regular self examination should follow the ABCD rule:
A (ASYMMETRY) meaning one half of the mole does not match with the other half
B (BORDER) meaning the border or the edges of the mole is irregular, ragged, scalloped, blurred or poorly defined
C (COLOUR) meaning the colour is not the same throughout the whole surface of the spot and varies in shades of tan, black, brown, red, blue, or white
D (DIAMETER) usually the diameter of a malignant lesion is greater than 6 millimetres, but can rarely also be smaller

How is melanoma treated in pregnant patients?
Are these investigations safe for the baby?

When the doctor suspects a melanoma, a dermatosopic examination followed by an excision of the spot will be performed and the tissue examined under a microscope (histopathologic examination); this will take 1 to 2 weeks. This examination will establish whether it is a melanoma and, if so, the thickness of the melanoma. The condition is staged in the same way in pregnant as in non-pregnant women.
In order to establish the stage of the melanoma, various features must be considered including:
- the thickness (how deep the melanoma has grown into the skin
  thin melanoma (<1mm deep) usually has a very good outlook)
- the type of the melanoma
- involvement of lymph nodes
- the spread of the melanoma into other organs (metastases)
Usually no further tests are done for thin melanoma.
Some other medical tests may be used for staging the melanoma: sentinel lymph node biopsy, ultrasounds, or MRI (magnetic resonance imaging). All these procedures are safe in
pregnancy. Sentinel node biopsy is used in some cases to know if the melanoma has spread beyond the skin, and is done by biopsy of the first lymph node into which the melanoma drains. Sometimes it may be worth waiting until after delivery, but if essential there is no evidence that the blue dye used harms the baby, but occasionally the mother can have a serious allergic reaction to it, which could harm the baby. Methods using  X-rays or radioactive isotopes must be avoided.   

How is melanoma treated in pregnancy?

What are the implications of the treatment for the baby?
The treatment depends on the stage of the melanoma. The first treatment of all melanoma is surgical (removal of the melanoma under local anaesthesia); no further treatment is needed for thin melanoma. This procedure is safe for the unborn baby.
For thick melanoma or ones that have spread chemotherapy may be considered. This should only be given after the first three months of pregnancy, and careful consideration given to use later in pregnancy because it can affect the baby. Another form of treatment for melanoma is immunotherapy which is not advised in pregnancy because it increases the risk of spontaneous abortions.  

Can melanoma spread to the baby?

In most cases of melanoma the baby will not be affected by the melanoma or by the treatment (surgical). 
If the disease is at a late stage, when lymph nodes or internal organs are involved (advanced disease), the disease may spread to the placenta and the baby. In this situation the placenta should be examined and baby watched for any signs of melanoma in the following months; however, this situation is very rare.  

Is melanoma contagious for other people?


Does pregnancy worsen the prognosis of melanoma?

Pregnancy itself does not worsen the prognosis of melanoma. 
However, in pregnancy diagnosis and treatment are often delayed which may lead to a late stage melanoma with a worse prognosis. It is therefore important to remove a mole that is suspicious for melanoma as early as possible.
Also, the melanoma does not influence the outcome of the pregnancy for mother and baby.  

What can I do if I had a melanoma in the past and want to become pregnant?

If you have had a melanoma and treatment for it some doctors recommend waiting for some time before becoming pregnant. This is because spreading of the melanoma (particularly thick melanomas) to lymph nodes and internal organs is possible for some years after a melanoma has been removed. However, there are no guidelines regarding the length of time a woman should wait before getting pregnant. The decision should be made, knowing all the facts about your melanoma, with your partner and your doctor.  

What can I do to avoid another melanoma?

There are some rules that help to prevent melanoma development and help to detect any melanoma as early as possible:

  • Examine all areas of your skin regularly, in order to detect any changing moles; apply the ABCD rule. Any changing mole should be examined by a dermatologist.
  • Avoid artificial ultraviolet light (sun beds or tanning lamps) and protect yourself from excessive sunlight.
  • Avoid peak-sun exposure between 10 a.m. and 4 p.m.
  • Use a broad spectrum sunscreen that will protect you against UVA and UVB (minimum factor 20) and apply it half an hour before going into the sun. But remember: covering up is better than using a sunscreen lotion!
  • Make sure you get enough vitamin D.

Web links to detailed leaflets:

While every effort has been made to ensure that the information given in this leaflet is accurate, Your own doctor will be able to advice in greater detail.  
This leaflet has been prepared by the EADV task force “skin disease in pregnancy”, it does not necessarily reflect the official opinion of the EADV
Updated July 2013