Section 26: Benign and Malignant Pigmented Lesions

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 ...