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Vitiligo

Vitiligo is a cutaneous disorder of unknown cause that destroys melanocytes in the skin, mucous membranes, eyes, and hair bulbs. It affects 1% to 2% of the world's population and at least 1 to 2 million individuals in the United States alone. There is no sexual predilection, and although all races are affected, it is more noticeable in patients with darker complexions. The peak onset of disease is between 10 and 30 years of age, and in half of the cases the disease manifests within the first two decades of life. This progressive disorder starts as white macules with an initial period of rapid spread that is followed by periods of latency. Spontaneous repigmentation is seen at times. There is an element of inheritance to this disorder because 30% of patients have a family member with vitiligo. Stress, illness, and personal crises have all been correlated with the onset of disease. Vitiligo has a profound psychological effect on patients, with two thirds of patients underachieving their potential because of psychosocial effects from their disease.

Clinically, patients present with well-circumscribed hypopigmented and depigmented macules. These macules are several millimeters to several centimeters in diameter and are oval-to-round in shape. They have scalloped (concave) edges that appear as if the affected areas are invading the adjacent normal skin. Convexity of the lesions is seen with repigmentation. Variations of the usual macules are trichrome and quadrichrome pattern with a third and even fourth intermediate color appearing within the lesion. The face, dorsal hand, wrists, axillae, umbilicus, and genitalia are common sites of affliction. Depigmented lesions with inflamed borders can be seen in 2% to 5% of patients. The Koebner phenomenon is physical injury inducing vitiligo at the traumatized site. This is seen in up to one third of patients, and the macules roughly resemble the site of original injury.

Childhood vitiligo is a distinct subset of disease seen in children under 12 years of age, in whom there is an increased incidence of segmental vitiligo. These children have a greater incidence of organ-specific serum autoantibodies and have poor therapeutic responses to topical PUVA. In a study of 82 children with vitiligo, their immediate and extended families had a much greater incidence of autoimmune and endocrine disease as compared to controls.

A variety of theories have been formulated to explain the cause of this disorder. The neural theory proposes that nearby nerve endings release a neurochemical mediator that is toxic to melanocytes. The self-destruction theory states that intermediates in melanin synthesis are toxic to melanocytes. Normally, these melanocytes can handle these dangerous metabolites, but imbalances in this system can occur.

Ocular pigmentary abnormalities (hypopigmented or hyperpigmented choroid and retinal pigmented epithelium, uveitis) have been reported in 40% of patients with vitiligo. Decreased acuity, poor night vision, and photophobia are seen in about 5% of patients. In a study of 35 patients with a matched control group, 43% (15) had one or more signs of thyroid disease as compared with 20% (7) of controls. Vitiligo patients also have a higher incidence of thyroid autoantibodies.

Diagnosis depends on a good history and physical examination. It is important to establish the course of the disease to determine the aggressiveness of subsequent treatment. Asking about precipitating factors, occupational chemical exposure, and recreational chemical exposure is vital because a variety of chemicals may produce leukoderma.

The goal of treatment is to restore pigmentation and thus improve the appearance of affected patients. The reserve melanocytes needed for repigmentation migrate from surrounding normal skin and hair follicles. Oral and topical psoralen photochemotherapy (PUVA), heliotherapy (trisoralen and sunlight), topical corticosteroids.

Of these, PUVA has the highest efficacy rate but may take several months of thrice weekly treatments to show substantial improvement. Newer therapies include dermabrasion and topical 5-fluorouracil, khellin and UVA light, and L-phenylalanine.

When using PUVA, it is essential to obtain an antinuclear antibody test to rule out lupus erythematosus, a disease in which phototherapy is contraindicated. A chemistry screen is usually performed because diseases of the liver and kidneys can affect oral psoralen metabolism. Autologous skin grafts may be helpful for isolated lesions. The side effects of this new therapy are scars, spotty repigmentation, and cobblestone texture of the skin. In vitiligo with little residual normal pigmentation, selective depigmentation may provide a more acceptable cosmetic effect.