A lentigo (plural lentigines) is a small, pigmented flat or slightly raised spot with a clearly defined edge that is surrounded by normal-appearing skin. Lentigo or lentigines may evolve slowly over years, or they may appear suddenly.
They may occur anywhere on the body and vary in colour from tan-brown to black. Viewed under the microscope a lentigo shows an increased number of normal melanocytes (skin cells that produce the pigment melanin that produces skin colour). Melanocytes appear to replace keratinocytes in the basal layer of the epidermis.
Although lentigines are benign (non-cancerous) by nature they must be carefully examined to differentiate them from early pigmented skin cancers such as melanoma.
What are the clinical features of lentigines?
Lentigines have been classified into many different types depending on what they look like, where they appear on the body, causative factors, and whether they are associated to other diseases or conditions.
Primary care management
Unsightly lesions of face can be lightly frozen, which often improves the cosmetic result.
Tretinoin is occasionally employed to lighten lesions (unlicensed use).
Secondary care management
Cryotherapy is used for isolated lentigines and is more effective than 40% trichloracetic acid for the treatment of solar lentigines.
Some studies have reported that cryotherapy is painful but analysis suggests this is more to do with the operator and the technique employed rather than the treatment per se.
One study showed that a mid-depth chemical peel with phenol resulted in greater patient satisfaction with the end result than cryotherapy for the treatment of solar lentigo but resulted in more pain, erythema and a longer healing time
Lasers are useful for a variety of lentigines. Aggressive therapy for using quality-switched lasers is effective in the treatment of solar lentigines but carries the risk of post-inflammatory hyperpigmentation (PIH).
For darker skin types, less intensive irradiation reduces this risk, with no reduction in efficacy.
Intense pulsed light (IPL) is another option.
When to refer
For doubt over diagnosis and for diagnostic biopsy.
When treatment is required but cannot be provided within primary care – eg, treatment with local chemical peel or lasers (Q-switched Nd:YAG or ruby) are effective when available.
Lentigines tend to get worse over time but do not go malignant.
- New lesions can be prevented to some extent by sun avoidance, use of sunblock creams and keeping on a shirt when outside in the sunshine.
- Avoiding the excessive use of sunbeds helps to prevent tanning-bed lentigines.
- Avoidance of a large single dose of ionising radiation helps to prevent radiation lentigines.