Vitiligo

Medical Definition and Overview

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Vitiligo is a chronic depigmenting disorder of the skin and hair characterized by circumscribed depigmented macules and patches. In patients with vitiligo, white patches of skin appear on different parts of the body. This occurs because melanocytes, the cells that make pigment (color) in the skin, are destroyed. It is a progressive disorder in which some or all of the melanocytes in the affected skin are selectively destroyed.

The prevalence of vitiligo is estimated at 0.5–2% of the population worldwide, with half of patients presenting symptoms before the age of 20 and 95% before the age of 40. While vitiligo may be more prominent in patients with darker skin, this disorder does not have a racial or ethnic predilection.

The majority of cases of vitiligo are sporadic in nature with a positive family history of vitiligo found in 20–30 % of the patients. Vitiligo is a multifactorial disease; autoimmune, genetic, autocytotoxic, neural, environmental, and genetic factors have all been implicated.

There is a strong genetic link as up to 30% of the affected individuals have a family predisposed individuals have a family history of the disorder and it seems that genetically predisposed individuals have melanocytes that are prone to damage which then undergo responses that lead to depigmentation.

Although men and women are affected by vitiligo at equal rates, there is a higher proportion of women who seek treatment. The psychological impact of vitiligo can be severe, especially in patients with skin of color, and include depression, low self-esteem, fear of rejection, and a decreased quality of life.

Although no inciting factors for vitiligo have been confirmed, stress, skin trauma, severe sunburn, pregnancy, and emotional stress have been reported by patients as events which preceded the onset of vitiligo.

Clinical Features

Vitiligo is separated into two forms, each with a different presentation and clinical course. Non-segmental vitiligo (NSV), also called generalized vitiligo, is the most common form, seen in approximately 90% of cases, and is generally more rapidly progressive in its course than segmental vitiligo.

Non-segmental vitiligo presents with depigmented macules and patches that occur in a bilateral distribution anywhere on the body but typically involves the face, axillary regions, dorsal hands, fingers, and feet.

Early lesions of vitiligo often have small depigmented lesions around larger lesions. New areas of vitiligo commonly occur over joints particularly of the hands, elbows, and knees.

When depigmentation occurs secondary to trauma or chronic pressure, it is known as the Köebner phenomenon. Occasionally, the depigmentation can have a transitional stage, known as trichrome vitiligo, in which normal, hypopigmented, and depigmented skin is present in the same location.

Segmented vitiligo (SV) is less common than NSV and typically begins at a younger age, with roughly 30% of cases presenting during childhood.

Segmental vitiligo is characterized by unilateral or localized depigmentation that can spread along the distribution of a dermatome or along Blaschko’s lines. Spread of SV to the contralateral side of the body is rare, and lesions tend to be more stable than those of generalized vitiligo.

In both segmental and non-segmental vitiligo, retention of hair pigment is a good prognostic sign, whereas leukotrichia can be seen in areas of depigmentation and signifies a poorer prognosis regarding the prospects of repigmentation of that area.

In aggressive forms of vitiligo, patients may develop extensive depigmentation, covering the majority of their body surface area.

Diagnosis and Differential Diagnosis

The diagnosis of vitiligo is usually made clinically by the distribution of the depigmentation, absence of textural change, and the presence of a hyperpigmented border. Illumination of the skin with Wood’s lamp helps to delineate the extent of the vitiliginous areas, as it accentuates and highlights areas that may not be seen easily in visible light and furthermore helps in the differentiation of disorders characterized by hypopigmentation. A biopsy may be necessary in some cases.

The differential diagnosis for vitiligo includes tinea versicolor Opens in new window, pityriasis alba Opens in new window, post-inflammatory hypopigmentation Opens in new window, idiopathic guttate hypomelanosis Opens in new window, nevus depigmentation Opens in new window, halo nevus, and piebaldism Opens in new window.

Histopathological Features

Histologic examination of the skin from a lesion of vitiligo reveals lack of melanocytes, often with a sparse infiltrate of lymphocytes. Immunohistochemical stainscan be done, which reveal the absence of melanocytes in the depigmented lesion with large, sometimes vacuolated, melanocytes at the edges of the lesion, often with melanin granules still present within keratinocytes.

Therapeutics

Treatment to encourage repigmentation in vitiligo includes both topical corticosteroids and immunomodulators, phototherapy with psoralen and ultraviolet A radiation (PUVA), narrowband ultraviolet B (NBUVB), and surgical modalities.

The expectations for repigmentation should be discussed with patients, as all therapies require a long-term commitment and strict adherence to the treatment protocol. Potent topical corticosteroids are an effective therapy and have been shown to achieve greater than 75% repigmentation in 56% of patients with long-term use.

Phototherapy with NBUVB, administered two to three times a week on alternating days, has been shown to achieve more than 75% repigmentation in 63% of patients after 1 year of treatment.

NBUVB has been shown to be superior to PUVA therapy with less side effects and is thus the treatment of choice for most patients. Patients with skin of color, recent onset of disease, and lesions on the face and trunk tend to respond best to phototherapy.

Topical immunomodulators such as tacrolimus and pimecrolimus have a lower side effect profile than topical corticosteroid, although repigmentation with these therapies is mainly seen on the head and neck with repigmentation rates ranging from 26 to 72.5%.

Surgical modalities with transplantation of unaffected skin to vitiliginous areas with punch grafting, epidermal blister grafting, split-thickness grafting, or autologous melanocyte suspension transplanting can be used for patients with stable vitiligo that is unresponsive to other therapies.

Local treatment with topical monobenzyl either of hydroquinone can be used in patients with severe depigmentation (>50%) in order to achieve a more even appearance of the skin. Depigmentation treatment is more commonly used in patients over areas that are visible to the public, such as the face and distal extremities.