Display Patient Information Leaflets

Lentigo Maligna and Melanoma ‘in situ’

Posted Thursday, 17 September 2020

Date Issued: March 2023

Review date: March 2025

A-171/skin/JD/Lentigo Maligna/Melanoma In situ Skin Cancer Team v7

PDF: lentigo and melanoma in situ final January 2018 v3.pdf[pdf] 144KB

What is lentigo maligna and melanoma in situ?

Lentigo maligna and melanoma in situ are the very earliest stage of a skin cancer called melanoma.

The word melanoma comes from the Greek word ‘melas’, meaning black. Melanin is the dark pigment that gives skin its natural colour. Melanin is made in the skin by pigment cells called melanocytes. After our skin is exposed to sunlight the melanocytes make more melanin, and so the skin becomes darker. Melanocytes sometimes grow together in harmless groups or clusters, which are known as moles. Most people have between 10 and 50 moles and often they are darker than the surrounding skin. Melanomas can arise in or near to a mole but can also appear on skin that looks quite normal. They develop when the skin pigment cells (melanocytes) become cancerous and multiply in an uncontrolled way.

Melanoma in situ

‘In situ’ means that the cancer cells have not had the opportunity to spread to anywhere else in the body. There are cancer cells in the top layer of the skin (the epidermis) but they are all contained in the area in which they began to develop. They have not started to spread or grow in the deeper layers of the skin and have not become invasive. This is why some doctors call in situ cancers ‘pre-cancer’. The prognosis is excellent.

Lentigo maligna

Lentigo maligna is a type of melanoma in situ. It is a slow growing lesion that appears in areas of skin that has a lot of sun exposure such as the face or upper body. Lentigo maligna grows slowly and can take years to develop. Similar to melanoma in situ, lentigo maligna is only in the top layer of skin.

What are the causes?

The cause of melanoma in situ and lentigo maligna is exposure to too much ultraviolet light in sunlight, especially in the first 20 years of life. They are especially common in pale white skinned people who live in sunny countries. The use of artificial sources of ultraviolet light, such as sun beds, also raises the risk of developing a melanoma.

What are the symptoms of lentigo maligna and melanoma in situ?

Lentigo maligna may appear as a long-standing discoloured patch of skin, most commonly on the face, which slowly enlarges and develops darker areas with in it. Most in situ melanomas do not cause any symptoms, but tingling or itching may occur. If a lentigo maligna or melanoma in situ is not treated early it could become hard and lumpy, it can bleed, ooze or become crusty.

If you are worried about any changes in an area of pigmented skin you should seek advice from your doctor.

Can lentigo maligna and melanoma in situ be cured?

Yes, the outlook for lentigo maligna and melanoma in situ is excellent. It is very rare for them to come back because they were ‘in situ’, therefore they will not have had an opportunity to spread elsewhere in the body.

How are they treated?

The treatment for lentigo maligna and melanoma in situ is surgery. An area of skin is taken in a procedure called an excision biopsy under a local anaesthetic. The specimen is checked under the microscope, your doctor will receive a report to confirm that the suspected diagnosis is correct. Following the biopsy, it may be necessary to have another operation called a “wider excision” this is where a margin of healthy tissue is removed from around biopsy scar to ensure that all of the lentigo maligna or melanoma in situ has been removed.

Once the biopsy is confirmed as clear you will be discharged back to the care of your GP.

Taking Care in the Sun

Stay in the shade between the hours of 11am and 3pm.
Make sure you never burn.
Avoid the use of sun beds.
Always cover up. Wear light cool clothing of a tight weave, wide-brimmed hats and U.V. protective sunglasses, look for the CE or BS EN 1836:1997 mark as these offer the highest protection.
Take extra care of children as their skin is delicate. Very young babies should be kept out of strong direct sunshine.
Use a sunscreen of factor 30 and above, according to your skin type, ensure the sunscreen has UVB and UVA protection. Look for the star rating ****or ***** on the label. The price is not important. Apply it 15-30 minutes before you go out and re- apply regularly; every 2-3 hours.