Chapter 24: Lentigines

INTRODUCTION

There are two major types of lentigines: lentigo simplex and solar lentigos. They are benign lesions. Although both are clinically identical, they appear in entirely different clinical settings. Lentigo simplex typically first present in childhood as multiple well-demarcated, brown or black macules that can appear on any part of the skin or mucous membranes. They are clinically indistinguishable from junctional nevi. There is no association with sun exposure in this type of lentigo. In contrast, solar lentigos, more commonly known as “liver spots,” are well-defined, brown macules that appear on sun-exposed skin of adults. They increase in number with age. They most often appear on the dorsal hands, shoulders, and face of lightly pigmented and red-haired patients.

EPIDEMIOLOGY

Incidence: very common, particularly in fair-skinned patients

Age: bimodal distribution in childhood and in sun-damaged skin of adults

Race: more common in Caucasians

Sex: equal

Precipitating factors: sun exposure is closely related to solar lentigines. Multiple lentigines are associated with a few genodermatoses including LEOPARD syndrome, LAMB syndrome, and Peutz–Jeghers syndrome

PATHOGENESIS

Unknown.

PATHOLOGY

There is a uniform elongation of the rete ridges of the epidermis along with increased melanin in melanocytes and basal keratinocytes. In addition, there are an increased number of melanocytes in the basal cell layer. Melanophages are present in the papillary dermis.

PHYSICAL LESIONS

Well-defined brown macules. Lentigo simplex macules tend to be evenly distributed and small, measuring only a few millimeters. Solar lentigos have a predilection for the sun-exposed areas of the dorsal hands and face. They can be larger than lentigo simplex.

DIFFERENTIAL DIAGNOSIS

Seborrheic keratosis, junctional nevi, ephelides, lentigo maligna, melanoma may all mimic lentigines.

LABORATORY EXAMINATION

Biopsy is indicated if there is suspicion of a lentigo maligna or melanoma. Medical workup is appropriate if there is suspicion for a genodermatosis.

COURSE

There is a bimodal distribution for lentigines. They appear in childhood and in sun-exposed adults.

KEY CONSULTATIVE QUESTIONS

• Has there been any change in the color or size of the lesion?

• Does the lesion bleed?

• Sun exposure

• Sunscreen use

MANAGEMENT

There is no medical indication to treat lentigines. The ...