Medically reviewed by Dr. A.M. van Coevorden, dermatologist
Melanoma in situa very superficial form of melanoma, only in the top skin layer
A melanoma in situ is a malignant collection of pigment cells that sits only in the top layer of the skin. It is a very superficial form of melanoma; after good treatment the malignant cells usually do not return and the chance of spread is very small. It sometimes develops in an existing mole, but more often without a prior mole.
- What is a melanoma in situ?
- How do you get a melanoma in situ?
- What symptoms does it cause?
- Is a melanoma in situ contagious?
- How is the diagnosis made?
- What treatments are there?
- When should you return for follow-up?
- Can a melanoma in situ be cured?
- What can you do yourself?
- Frequently asked questions about melanoma in situ
What is a melanoma in situ?
Pigment cells (melanocytes) form a mole when grouped together. When they change and proliferate, it is called a melanoma. A melanoma in situ is a malignant collection of pigment cells, but only in the top layer of the skin (the epidermis). After good treatment the malignant cells usually do not return.
How do you get a melanoma in situ?
A melanoma in situ can develop anywhere on the skin, sometimes in a long-standing mole, but more often without a prior mole. Its development is linked to heredity and environmental factors, especially the sun. The risk is higher with one or more of the following: family members with melanoma, blistering sunburn at a young age, sunbed use or excessive sun, fair skin with red or blond hair, several large moles of different colours, more than a hundred moles, a previous melanoma, or an outdoor occupation.
What symptoms does it cause?
Watch for these signs: a new, often striking dark brown to black spot; an existing mole that changes (grows, gains different colours, darkens, thickens or changes shape); or a mole that itches, hurts, bleeds or opens.
Is a melanoma in situ contagious?
No. A melanoma in situ is not contagious.
How is the diagnosis made?
The dermatologist assesses with a dermatoscope (a small hand microscope) whether a mole looks suspicious. On suspicion the spot is surgically removed and the tissue examined under the microscope by the pathologist, which establishes with great certainty whether it is a melanoma in situ.
What treatments are there?
The dermatologist or surgeon removes the spot under local anaesthetic, after which the tissue is examined under the microscope. If the diagnosis is confirmed, a second operation always follows, removing a half-centimetre safety margin around the scar to minimise regrowth at the same site. Additional lymph node examination is not needed; that is only needed for melanomas that grow deeper into the dermis. X-rays, ultrasounds or scans are also not needed.
When should you return for follow-up?
For symptoms or concerns about spots, always make an appointment promptly. Usually you return once for a check, at which the dermatologist explains how to examine your skin yourself. Further checks are usually not needed afterwards, although the dermatologist may decide to see you yearly, for example with many moles or melanomas in the family.
Can a melanoma in situ be cured?
A melanoma in situ is a very superficial form of skin cancer; the chance that it returns and spreads after treatment is very small. Because its development is linked to sun exposure, there is a chance of a second melanoma or other skin cancer during your life. The diagnosis of skin cancer can cause a lot of worry; some people have psychological complaints afterwards. It is important to discuss these worries with your doctor, so it can be considered whether extra help from specialists would benefit you.
What can you do yourself?
Avoid sunburn and do not use a sunbed. Know your own skin and check your moles, using photos or someone else's help; how often varies per person, ask your dermatologist. Go to the GP or dermatologist for a new mole, for changing or symptomatic moles, for skin changes around the surgical scar, or for enlarging lymph nodes.
Frequently asked questions about melanoma in situ
Is a melanoma in situ dangerous?
It is a very superficial form of melanoma, only in the top skin layer. After good treatment the chance of return and spread is very small.
Why a second operation?
To take a half-centimetre of healthy skin around the scar, so the chance of regrowth at the same site is minimised.
What should I watch for with my moles?
A new striking dark spot, and a mole that grows, changes colour or shape, thickens, itches, bleeds or opens.
Do my lymph nodes need examining?
No. That is only needed for melanomas that grow deeper. For a melanoma in situ, scans are not needed either.
Can I still get a melanoma?
Because its development is linked to the sun, there is a chance of a second melanoma or other skin cancer. That is why self-checks and sun protection stay important.