What is a solar lentigo?
A lentigo is a flat or slightly raised brown lesion with a clearly marked edge. A lentigo can be distinguished from a true freckle (ephelis) by the darker colour, wider distribution and the fact that they do not fade in the winter months. They are very common and there are several kinds of lentigines.
What do lentigines look like?
Lentigines have been classified into several different types depending on what they look like, where they appear on the body, what causes them, and whether they are associated with other conditions. The majority of these do not change or disappear in adult life.
Simple lentigo (lentigo simplex)
The most common type of lentigo, these are mainly seen in children and are not associated with sun exposure. They are commonly found on the trunk and limbs and size usually varies from 5 to 15mm in diameter.
Related to sun exposure, these are benign (non-cancerous) lesions found on areas commonly exposed to the sun such as hands, face and lower legs. They are usually less than 5mm in diameter but may merge to form later spots. They may vary in colour from yellow, brown to black and may often disappear. Patients often have multiple lesions but can present with a single lentigo on the face, which is usually a uniform, single light brown or mid-brown colour.
How is the diagnosis made?
Lentigines are usually diagnosed clinically by their typical appearance. Occasionally we may need to see you in clinic to assess the skin lesion more closely with a polarised magnification device called a dermatoscope to look at structures in the skin more closely.
If there is uncertainty around the diagnosis, or an unusual appearance, your doctor may suggest a biopsy. This is where a piece of skin is removed under local anaesthesic and sent for analysis by a pathologist.
Treatments for lentigines
Most lentigines are left alone, unless there is uncertainty around the diagnosis or an unusual appearance. Treatment is not usually available on the NHS, unless there is diagnostic uncertainty.
Curettage and cautery (gentle scraping under local anaesthetic)
Intense pulsed light laser (IPL) therapy
SPF 50+ broad-spectrum sunscreen
How can lentigines be prevented
Lentigines associated with exposure ultraviolet radiation can be prevented by very careful sun protection. Clothing is more successful at preventing new lentigines than are sunscreens.
What is the outlook for lentigines?
Lentigines usually persist. They may increase in number with age and sun exposure. Some in sun-protected sites may fade and disappear.
What do I need to look out for?
You should see your GP for advice if you notice any changes such as change in size, shape or colour, bleeding or notice any irregular or dark colours or an irregular shape.
See the example of a changing lentigo that was diagnosed as lentigo maligna (pre-cancerous skin change).