Lentigines are asymptomatic small, brown macules. There are three major types: lentigo simplex, solar lentigo, and lentigo maligna.

Lentigo simplex may occur anywhere on the skin or mucous membranes. It is a small macule, approximately 1 to 8 mm in diameter, tan to dark brown or black in color, and uniformly pigmented. Lentigo simplex is not related to sun exposure. In Peutz–Jeghers syndrome, simple lentigines are associated with polyps of the gastrointestinal tract and increased risk of gastrointestinal or genitourinary carcinoma (Fig. 68-1).

Solar lentigo, known by the lay term “liver spot,” has a similar appearance to that of lentigo simplex, but is induced by sunlight. It develops on the sun-exposed areas, usually in older people, and can be larger than lentigo simplex, up to 2 cm in diameter.

Lentigo maligna is a large brown patch with irregular pigmentation and shape on the sun-damaged skin (Fig. 68-2). It is most common in patients older than 60 years. Approximately 5% of lentigo malignas progress to lentigo maligna melanomas; they are therefore sometimes referred to as “malignant melanoma in situ.”