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FRECKLES AND LENTIGINES

Freckles

Light brown or tan macules scattered on the face or nose of a light-skinned, red-haired patient, in response to sun exposure, are characteristic (Fig.31.77; see also Tables 31.4 and 31.5; see also Ch.17). Freckles do not require treatment, but instead the education of the patient and parent on the need for sun avoidance is important. Surprisingly, many parents resist the notion that freckles are sun-induced. Instead, they believe they are purely inherited. The tendency to develop freckles is of course inherited, but strict sun avoidance will prevent their development. With proper protection, these lesions will fade on their own. Light cryotherapy may be tried initially if lesions are limited. The 510-nm dye laser has been used.

Solar lentigo

The solar lentigo is a brown macule on sun-exposed and damaged skin. Multiple symmetric, tan-brown macules on the face, arms, or dorsa of the hands in an older patient with a history of chronic sun exposure are characteristic (Fig. 31.78). Both solar lentigines and freckles are pigmented macules occurring in response to sun exposure, but significant differences exist between them (Table 31.5).

    Sun protection is important for prevention. Cryotherapy is a simple and effective therapy. Various lasers, for example frequency-doubled Q-switched neodymium:yttrium–aluminum–garnet (Nd:YAG), can produce excellent results. Alternatives include topical retinoids or chemical peeling.

Figure 31.77 Freckles. Multiple brown macules on the sun-exposed areas of the face, arms, and trunk of a child are typical for freckles. Such patients' parents should be encouraged to provide sun protection for their children.

Figure 31.78 Solar lentigo.

Labial melanotic macule

The labial melanotic macule may be thought of as a solar lentigo on the lower lip. A brown macule on the middle third of the lower lip of a young, pale-skinned man is characteristic (Fig.31.79). The median size in one study was 4mm. The lesion should be biopsied if there is a question
of malignancy. Cryotherapy, simple excision, the Q-switched ruby laser, or the non–Q-switched ruby laser may be used.

PRACTICE POINTS

Agminated lentiginosis

This larger pigmented lesion probably results from some localized genetic abnormality. Multiple pigmented macules are distributed in a quasidermatomal pattern. Often the neck and upper shoulders of one side are affected (Fig.31.80). There is no specific treatment. The clinician and patient should watch for any pigmented lesions that stand out from the others. If any develop, a biopsy should be performed.

Figure 31.79 Labial melanotic macule. A pigmented macule on the lower lip is typical of a labial melanotic macule. This lentigo is secondary to chronic sun exposure.

Figure 31.80 (a,b) Agminated lentiginosis on the left breast, axilla, and arm.

Figure 31.81 Penile melanosis. This benign lesion has all the features of melanoma. A biopsy is mandatory.

Penile melanosis

Irregularly shaped, pigmented patches on the glans or shaft are characteristic (Fig.31.81). A biopsy is necessary to establish the diagnosis and exclude any forms of malignancy (e.g. melanoma). Following these lesions photographically and biopsying any new foci is appropriate. The Q-switched ruby laser has been used successfully.

LEOPARD syndrome

This mnemonic stands for lentigines, electrocardiogram abnormalities, ocular hypertelorism, pulmonic stenosis, abnormal genitalia, retardation of growth, and deafness (Fig.31.82). Mutations in PTPN11, a gene encoding the protein tyrosine phosphatase SHP-2, located at chromosome 12q24, have been identified in patients with LEOPARD syndrome. The darkly pigmented freckles or lentigines begin in infancy and progress. An autosomal dominant inheritance pattern occurs. Only some of the non-cutaneous findings may be present in any one patient. An electrocardiogram should always be obtained. Intense pulsed-light technology has proved effective at removing lentigines.

Carney complex

Multiple facial pigmented macules may occur in Carney complex, which is characterized by pigmented skin lesions (lentigos and blue nevi), myxomas (of the skin, breasts, and heart), functioning endocrine tumors (e.g. bilateral primary pigmented nodular adrenocortical hyperplasia and growth hormone-secreting pituitary adenomas), psammomatous melanotic schwannoma, and testicular tumors (Fig. 31.83).

Other lentiginoses

Patterned inherited lentiginosis of blacks is discussed in Chapter 21, and Peutz–Jeghers syndrome in Chapter 12.

White/Cox: Diseases of the Skin, 2ed.(c) 2006, Elsevier Inc. All rights reserved.