Epidemiology and clinical manifestations

Vitiligo is either most common or most recognized in darkly complexioned patients, particularly African Americans and those of Middle East extraction. This occurs in approximately 1% of patients¹.

The hallmark of vitiligo is its clinical appearance. The presenting complaint is generally one of cosmetic unacceptability, although most patients are only minimally bothered by vitiligo of the genitalia. Itching and pain are absent.

Vitiligo presents as well-demarcated, depigmented (totally white as compared to only light) patches (Figure 22.1). Vitiligo of the vulva usually affects keratinized, hair-bearing skin, the perineum, and perianal skin. Extragenital vitiligo is usually, but not always, present. A general skin examination most often shows similar patches over the extensor surfaces of joints, including the dorsal hands and fingers, wrists, knees, and elbows. Vitiligo is often perioroficial, occurring around the mouth, eyes, and nares. Vitiligo exhibits the Koebner phenomenon, in which areas of irritation or trauma are preferentially affected, partially accounting for this distribution (Figure 22.2).

Figure 22.1 Vitiligo is characterized by asymptomatic, well-demarcated white patches with no surface change of scale, thickening, or crusting.

Figure 22.2 Because vitiligo preferentially affects irritated or inflamed skin, vitiligo in the setting of other skin disease such as lichen sclerosus or lichen simplex chronicus (LSC) is relatively common, as seen here in this patient with lichenified LSC and vitiligo. The diagnosis is more obvious when extragenital vitiligo is present as well.

Diagnosis and differential diagnosis

Vitiligo superficially resembles other white diseases, especially lichen sclerosus (Table 22.1). Lichen simplex chronicus in areas of moist modified mucous membranes is sometimes white as well. However, lichen simplex chronicus and lichen sclerosus show surface texture change, whereas vitiligo shows color change only.

Table 22.1 Vitiligo

Like vitiligo, postinflammatory hypopigmentation consists of light patches without texture change or thickening, but postinflammatory hypopigmentation is not white, only lighter in color than surrounding skin, and it is usually less well demarcated. Occasionally, inflammation, as a result of the Koebner phenomenon, precipitates vitiligo, so that depigmentation occurs in the area of active or past inflammatory disease (see Figure 22.2).

Laboratory findings and histology

No laboratory findings regularly occur in patients with vitiligo. However, patients with vitiligo are more likely to exhibit laboratory manifestations of hypothyroidism, so thyroid function tests should be measured. Patients sometimes also show signs of inflammatory eye disease, and an ophthalmologic examination is recommended by some.

A biopsy is rarely performed to make the diagnosis of vitiligo. However, routine histology generally shows normal skin, although the borders of lesions occasionally reveal a mild lymphocytic infiltrate. Silver stains show an absence of melanocytes.

Pathogenesis

Vitiligo is disease that may be multifactorial, including an autoimmune factor, characterized by antibodies against melanocytes as well as cellular immunity^1,2. Environmental factors and metabolic abnormalities leading to damage to melanocytes, particularly in the setting of oxidative stress, and possible neurologic abnormalities may also play roles^3,4.

Therapy and prognosis

There is no predictably beneficial treatment for vitiligo. Other than reassurance and education, vitiligo of the genitalia is generally not treated. Occasionally, vitiligo improves with topical corticosteroid therapy, but this is most likely in children, and the experience of this author suggests that genital vitiligo is more difficult to treat successfully with topical corticosteroids than other areas⁵. There are reports of both benefit and no efficacy with the calcineurin inhibitors tacrolimus and pimecrolimus, although this is irritating to many patients^6,7. Topical calcipotriene has been reported as useful in small series⁸. Although ultraviolet light treatments have been reported as beneficial for vitiligo, this therapy is usually avoided on genital skin because of the risk of squamous cell carcinoma⁹. The 308-nm excimer laser has been reported useful as well¹⁰. Finally, skin grafts sometimes prompt repigmentation of vitiligo.