Ephelis This is the learned word for a freckle. The plural is ephelides (pronounced ĕf-ĕl-ĩ-dēz). These brown macules are exceedingly common on the face in some children. They appear after exposure to sunlight and are more common in children with very fair skin or red hair. They tend to disappear in adult life. Histologically, these lesions show increased amounts of epidermal melanin but no abundance of melanocytes.

Lentigo This tan-to-brown to almost brown-black macular lesion may be found on any area of the body surface, which includes mucous membranes. There is no relation to ultraviolet light exposure. The illustration here is of lentigines on the lip. Lentigines may be present at birth and tend to increase in number during childhood and adult life. Histologically, there is a proliferation of melanocytes and elongation of the rete ridges. Lesions of this sort show no tendency to resolve spontaneously.

Peutz-Jeghers syndrome This autosomal dominant syndrome is notable for highly characteristic lentigines seen on the vermilion of the lips and adjacent skin, on the buccal mucosa, and on the palmar aspect of the fingertips. Figures 26-3 and 26-4 are good representations of the lentigines in a typical case.

Patients with this syndrome may also have gastrointestinal polyps throughout the GI tract but most frequently in the jejunum. These benign hamartomas have very little malignant potential but may be the cause of obstruction, diarrhea, bleeding, or intussusception. Unlike common lentigines, the cutaneous lesions in these patients tend to fade during adult life. Mucous membrane lesions persist.

Multiple lentigines syndrome This autosomal dominant syndrome features numerous small lentigines, which are present at or soon after birth and cover the entire cutaneous surface. Previously known as the mnemonic LEOPARD syndrome, the common findings are summed up as follows in which l stands for lentigines, e for electrocardiographic conduction defects, o for ocular hypertelorism, p for pulmonary stenosis, a for abnormalities of genitalia, r for retardation of growth, and d for deafness. Mutations in the PTPN11, RAF1, or BRAF genes cause multiple lentigines syndrome.

Junctional nevus The macule of hyperpigmentation pictured in Fig. 26-6 is the most common form of nevocytic nevus in childhood. The so-called junctional nevus is a benign lesion that is composed of melanocytic nevus cells along the dermoepidermal junction. Lesions of this sort may arise in crops after the first year of life. As nevus cells migrate into the dermis, the typical junction nevus becomes a compound nevus. This process usually occurs during adolescence and early adulthood.

Compound nevus The ordinary mole has great variety in intensity of brown color, size, shape, and location. Those termed compound nevi are composed of melanocytes that are gathered into thèques or nests at the dermoepidermal junction and in larger, less compact collections deeper in the dermis. Shown in Fig. 26-7 is a plaque that is light brown and of fairly large size as compound nevi go. Figure 26-8 shows a papule that is reddish-brown and of a more usual size. Such lesions are thought to start out as junctional nevi, which then go on to more melanocytic proliferation; melanocytes continue to drop off and down, becoming collections in the dermis. At any time in the development of compound nevi, melanocytes are found both at the dermoepidermal junction and in the dermis. Generally speaking, these lesions are benign and remain so. If cosmetically objectionable, they may be excised or shaved off. Histologic examination of all surgically removed pigmented lesions is advisable.

Intradermal nevus Figures 26-9 and 26-10 illustrate common moles in which the collections of melanocytes are entirely intradermal. Such lesions do not show any thèques or nests of melanocytes at the dermoepidermal junction. They too come in a great variety of colors, shapes, sizes, and sites. Intradermal nevi are the end stage of development of junction and compound nevi. As with junction and compound nevi, they are extremely common and benign. Like compound nevi, they may be ablated by shaving or elliptical excision. Treatment by these methods does not increase the possibility of malignant transformation.

Melanonychia This lesion presents as a brown or black longitudinal streak along the nail. The pigmentation is most commonly caused by increased melanin by melanocytes in the nail unit. Melanonychia may be caused by physiologic factors such as racial pigmentation, trauma, dermatologic conditions, infection, medication, or systemic disease. In children, melanonychia is often caused by nevi.