Section 24. Miscellaneous Pigmentary Disorders

This condition is characterized by whorled areas of hypopigmentation following lines of Blaschko that are present from birth or evolve during early childhood. The lesions may be generalized, with individual areas of hypopigmentation assuming whorled or streaked patterns. A very small number of patients with this pigmentary disorder have central nervous system disease, usually manifest as seizures or mental retardation. Other reported abnormalities include skeletal and ocular defects. This condition was formerly called hypomelanosis of Ito.

This is a congenital condition characterized by hyperpigmentation that follows lines of Blaschko in a linear pattern on the extremities and a whorled pattern on the trunk. The hyperpigmentation may be present at birth or develops shortly thereafter, spreading during the first 2 years of life, at which time it stabilizes.

These are localized areas of hypopigmentation that are usually present at birth. The lesions may be irregular in size and shape and occasionally follow a linear or segmental pattern. Electron microscopic study of these areas suggests that melanosomes are not being transferred from melanocytes into surrounding keratinocytes. There are no associated abnormalities.

This circumscribed area of macular hypopigmentation is due to a localized vascular abnormality. Chest and back are the most common locations. In contrast to nevus depigmentosus, erythema does not develop in response to stroking or the application of ice or warm water. Hypersensitivity of the involved vessels to catecholamines has been postulated as a cause.

The vegetable pigment carotene is widely distributed in carrots, lettuce, squash, and many other vegetables and fruits. A diet that is very rich in these foods results in a yellowish-orange discoloration of the skin. This appearance is usually localized to the palms and soles (note the hand on the left) but may also involve the skin of the face. The presence of normal sclerae distinguishes the clinical appearance of this condition from that of jaundice. Return to normal skin color follows a reduction in dietary intake of carotene.

This genetic disorder is transmitted as an autosomal dominant, with variable penetrance. It is characterized grossly by partial albinism in the form of a white forelock (Fig. 24-7), broad nasal root (Figs. 24-7 and 24-8), hypertrichosis of the inner portions of the eyebrows, lateral displacement of the medial canthi (Figs. 24-7 and 24-8), partial or complete heterochromia of the irides (Fig. 24-7), and complete or unilateral deafness. In African Americans, blue irides, vitiligo, and pigmentary changes in the fundi may be seen. There are no other constitutional symptoms, but the hearing loss and unusual appearance may pose handicaps.

Patients with this autosomal dominant condition have congenital patches of depigmentation. Most have a white forelock, with involvement of adjoining scalp and forehead in a triangular pattern. There may be other areas of involvement on the trunk and extremities. Electron microscopic examination of affected areas reveals a complete absence of melanocytes. Management must include the appropriate use of sunscreen lotions on depigmented skin.

This condition is characterized by congenital hypopigmentation of the skin, hair, and eyes. Almost all of the many varieties are inherited in autosomal recessive fashion. Photophobia is a significant problem for most patients. The lack of protective melanin leads to extreme sun sensitivity and results in a high incidence of actinic keratoses, basal cell carcinomas, and squamous cell carcinomas. The avoidance of sun exposure by using protective clothing and sunscreen preparations is critical.

About one-half of patients with vitiligo have onset of their disease during childhood or adolescence. Patients may present with hypopigmented and depigmented macules of various sizes and shapes. The area of involvement surrounding the eye in Fig. 24-12 represents one fairly typical distribution. Note the associated depigmentation of eyebrows and eyelashes. Periorificial vitiligo may also involve the skin around the mouth, rectum, and genitalia. Vitiligo may occur only on the distal extremities or may be unilateral and segmental, as in Fig. 24-13. Vitiligo may be associated with uveitis and peripheral retinal scarring, but these changes rarely affect vision. The frequent presence of antibodies to melanocytes in individuals with vitiligo suggests an autoimmune etiology. A number of other autoimmune disorders, including Addison's disease and Hashimoto's thyroiditis, are more common among patients with vitiligo and their relatives.

These are more illustrations of fairly extensive cases of vitiligo. The condition tends to progress and may even become universal. A variety of treatment modalities are commonly employed, with varying degrees of success. The patient and family should be made aware of the sophisticated cover-up cosmetics that are now available. The use of broad-spectrum sunscreen lotions during the summer months minimizes the contrast between normal and involved skin. For some patients, the application of topical corticosteroids alone or with brief natural sunlight exposure early in the course of the disease may induce repigmentation. Narrowband UUB is also an effective treatment. Varying combinations of topical or oral psoralens and ultraviolet A light (PUVA) are used in the treatment of vitiligo.

This genetic disorder, recessive in mechanism of transmission, is extremely rare. It is characterized by albinism, photophobia, lymphadenopathy, hepatosplenomegaly, and susceptibility to pyogenic infection. The peripheral blood smear reveals giant granules within lymphocytes. The high incidences of serious infection and lymphoreticular malignancy contribute to a poor prognosis.

This linear stripe of hypopigmentation in the mid-chest and abdomen is termed linea alba. Linea nigra is its hyperpigmented counterpart. This is one of several locations for the extremely common and completely benign pigmentary demarcation lines. Other sites include the upper lateral arms, the mid-posterior legs, and the central back. There may also be two symmetrical lines crossing from the mid-clavicle to the areolae.

A wide variety of dermatologic diseases may leave either temporary or permanent hypopigmentation. Figure 24-18 shows loss of pigment in the popliteal fossa of a child who has atopic dermatitis. This process results from the inflammatory disease itself and from chronic scratching. The same phenomenon is shown on the face in Fig. 24-19. This is probably also the result of atopic dermatitis. Postinflammatory hypopigmentation can usually be easily differentiated from vitiligo. The lesions that follow inflammatory skin disease are less well defined and are more off-white than stark white. The symmetry that may occur in vitiligo is not seen here. For most children, postinflammatory hypopigmentation is temporary. Parents should be reassured that even the most disfiguring patterns of pigmentary alteration will resolve with proper therapy and time.

This is a group of conditions characterized by nevus flammeus in combination with other birthmarks. The other lesions may be blue spots (dermal melanocytosis), nevus spilus, or nevus anemicus. This patient has a large area of vascular discoloration accompanied by an area of dermal melanocytosis. According to one of several classification systems, this would be termed type IIA.