|In diagnosing and managing patients with lentigines, it is important to distinguish between malignant and benign lesions. A seven-point weighted checklist may be useful. Any suggestion of a malignant change in a lesion should be referred immediately to a dermatologist.Key wordsMelanoma, solar keratoses, naevus of Ota, cryotherapy, laser, peeling agents
Lentigines are small, pigmented, flat or slightly raised lesions with a well-defined edge, usually appearing within normal surrounding skin (see box 1).
They can develop anywhere on the body and evolve slowly over years or appear quite suddenly. The colour varies from black to light brown.
Histologically, there is a replacement of keratinocytes by melanocytes in the epithelial basal layer.
|BOX 1: DISTINGUISHING TYPES OF LENTIGINE
|Types of lentigine
|Simple lentigoPigmented flat or raised lesions with a clearly defined edge. They can be single or multiple and often appear in childhood
|Solar lentigoPigmented lesions appearing on sun-exposed sites, increasing in incidence from middle age. These are often known as age spots or liver spots
|Ink spot lentigoUsually a single dark lesion, often among a number of solar lentigines. The pigment pattern within the lesion is monomorphic
|FrecklesOften occur in fair-skinned individuals and tend to fade or disappear in the winter. They occur on the face and other sun-exposed areas
|Tanning salon lentigoOften appear as multiple pigmented lesions in people who use tanning beds
|May be mistaken for lentigo
|Solar keratosesScaly, sometimes pigmented lesions on sun-exposed areas
|Seborrhoeic wartsScaly brown lesions that are superficial and can often be picked off. Usually have a characteristic dermatoscopic appearance
Solar lentigines on the upper back may serve as a key marker of a patient who has had a significant history of sunburn and is therefore at risk of developing melanoma in the future.1
It is important to distinguish benign lesions from malignant ones and a good method is the seven-point weighted checklist (see box 2).
It is almost always better to remove a lesion for histology if there is any suspicion of malignancy.
Provided a pigmented lesion is benign, it can be left alone; however, many patients request treatment, which is not currently funded by the NHS.
|BOX 2: WEIGHTED CHECKLIST FOR REFERRAL
|Score of three or more suggests referral needed
|Major features (two points each)
|Change in size
|Minor features (one point each)
|Itch/change in sensation
Treatment can be divided into physical and topical therapies. Isolated lentigo can be treated with cyrotherapy. Destruction of melanocytes occurs at -4 to -7°C, whereas squamous cells can resist destruction to below -20°C.2
This is a convenient way to destroy these lesions and appears to be the current treatment of choice.3 However, there are potential side-effects with this procedure, such as associated hypopigmentation and pain.
Laser therapy can also be effective in the treatment of lentigines. The choice of laser is broad because of wide frequency of absorption of melanin, which is the target pigment. Green light lasers are only helpful in epidermal lentigo, owing to their lack of penetration, but they are excellent for treating these lesions, especially on the face and hands.4
For deeper lentigines, the laser of choice appears to be a Q-switched infrared laser, which is especially effective with naevus of Ota.5
Ablative CO2 and fractionated lasers work in a non-specific way and can be effective, but may risk further adverse effects. Laser treatment in combination with topical retinoids and antioxidants can be even more effective.6
Topical treatments include the use of chemical peeling agents. There are a variety of peels available that target melanin production in the skin, usually as competitive inhibitors of tyrosinase. Combined with sunblocks, these can be effective in reducing the appearance of mottled skin caused by photodamage.
In one study, cryotherapy was found to be slightly better than using a peel containing trichloroacetic acid (TCA) 33% in those with lighter skin, but the TCA-containing peel was favoured in those with darker skin.7
Cryotherapy is reported to be more painful and tends to cause hypopigmentation, which can be a disadvantage in those with darker skins.
Skin-bleaching creams can also be effective and there are many products on the market.
There have been no comparative studies of any size of the treatment of lentigines so it is difficult to suggest that one treatment is any better than another, but using a combination of topical bleaching agents is likely to be better than monotherapy.
In one study, combination topical therapy using 2% 4-hydroxyanisole/0.01% tretinoin was shown to markedly reduce lesion darkness, with few side-effects.8
A combination of physical and topical treatments probably produces the best cosmetic results. A cost-effective treatment would be cryotherapy followed by maintenance with a combination bleaching agent and sunblock.
For more extensive lesions, a tyrosinase-inhibiting peel and combination skin-lightening creams would probably represent the best therapeutic option. None of these therapies is available on the NHS for the treatment of lentigines.
- Dr Paul Charlson is a GPSI in dermatology in east Yorkshire
Competing interests: Dr Charlson is medical director of Skinqure Clinic, which provides treatment for lentigines
1. Derancourt C, Bourdon-Lanoy E, Grob J et al. Multiple large solar lentigos on the upper back as clinical markers of past severe sunburn: a case-control study. Dermatol 2007; 214(1): 25-31.
2. Leroy D, Dompmartin A, Dubreuil A. Cryotherapy of PUVA lentigines. Br J Dermatol 1996; 135: 988-90.
3. Ortonne JP, Pandya AG, Lui H et al. Treatment of solar lentigines. J Am Acad Dermatol 2006; 54(5 Suppl 2): S262-71.
4. Scheinfeld N, Goldberg D. Laser treatment of benign pigmented lesions. Available from: http://emedicine.medscape.com/article/1120359-overview (accessed 11 March 2014).
5. Lee W, Han S, Chang S et al. Q-switched Nd:YAG laser therapy of acquired bilateral nevus of Ota-like macules. Ann Dermatol 2009; 21(3): 255-6.
6. Guerrero D. Dermocosmetic management of hyperpigmentations. Ann Dermatol Venereol 2012; 139(Suppl 3): S115-18.
7. Raziee M, Balighi K, Shabanzadeh-Dehkordi H et al. Efficacy and safety of cryotherapy vs trichloroacetic acid in the treatment of solar lentigo. J Eur Acad Dermatol Venereol 2008; 22(3): 316-19.
8. Fleischer A Jr, Schwartzel E, Colby S et al. The combination of 2% 4-hydroxyanisole (Mequinol) and 0.01% tretinoin is effective in improving the appearance of solar lentigines and related hyperpigmented lesions in two double-blind multicenter clinical studies. J Am Acad Dermatol 2000; 42(3): 459-67.