Copyright 2022 - Custom text here

Lentigines (pleural of lentigo) are flat brown lesions which do not darken following sun exposure (thus differentiating them from ephelides or true freckles).

Appearance

One study of Caucasian women found that lentigines were signs of photo-damage whereas there was a genetic component in true freckles. They may be any size from 5-20 mm and may be irregular in shape. They occur over the shoulders in young people, especially those who have had a lot of sun exposure and in the elderly on the sun-exposed sites such as the dorsum of the hands and forearms, the face and the neck.

tt008

The histopathology may include hyperplasia of the epidermis and pigmentation of the basal layer.

Melanoma - tends to have more variation in colour density within the lesion than a lentigo.

Lentigo maligna - seen mainly on the sun-exposed areas of the face and neck in the elderly, is slow-growing and usually quite large (>20 mm). Their size and site differentiates them from lentigines. Lentigo maligna is a pre-cancerous condition. Conversion to a lentigo maligna melanoma can take from a few months to up to 15 years and occurs in approximately 5% of patients. Identifying lesions that require referral is not easy but worrying signs include changes in size or colour, itching, burning, bleeding, or pain. The ABCDE rule of melanoma may be helpful:

• A - Asymmetry.
• B - Border irregularity.
• C - Colour variegation.
• D - Diameter greater than 6 mm (the end of a pencil head), although melanoma can occur in lesions less than 6 mm.
• E - Enlargement.

Investigations

• Biopsy and histology may be used to differentiate the various types of lentigines.
• A dermatoscope is is occasionally used in the diagnosis of solar lentigo.

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.

Prognosis
Lentigines tend to get worse over time but do not go malignant.

Prevention

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.