6.3.4 Vitiligo

Acquired depigmentation disorder caused by auto-immune destruction of melanocytes in the epidermis and hair follicle.

It is a complex, initially reversible, autoimmune process affecting melanocytes. The principal two forms, segmental and non-segmental vitiligo differ in their pathogenesis. In the most common form of non-segmental vitiligo, intrinsic defects based on a polygenetic background lead to to increased vulnerability of melanocytes, increased oxidative stress and activation of an innate immune response. This is is followed by activation of the adaptive immune system with development of an IFN-γ signature in which melanocyte-specific CD8+ T-cells are generated and attack melanocytes.

The lesions are often asymptomatic. Pruritus can occur. Lesions can be disfiguring. Circumscribed small (sometimes confetti- like) macules develop, which may become confluent to produce larger patches. The disease is usually symmetrical (non-segmental vitiligo) and shows a complete depigmentation (rather than hypopigmentation), especially when examined under Wood’s light. Segmental vitiligo is unilateral and has a segmental distribution.

Vitiligo favours the face, dorsal aspects of the hands and feet, knees, elbows, anogenital region and peri-umbilical area, but any location is possible. Sometimes the disease is generalized, with little body surface area (BSA) spared.

Rule of nine procedure for estimation of BSA. Other scoring systems are Vitiligo Area Scoring Index (VASI) or Vitiligo Extent Score (VES).

Markers of disease activity are the Koebner-phenomenon, confetti lesions, hypochromic borders, trichrome and inflammatory vitiligo, the latter with presence of erythematous margins around the depigmented lesions.

Leuokotrichia can occur and is considered a poor prognostic sign due to involvement of hair follicle melanocytes.

• Segmental (affecting only one side of the body)

• Non-segmental (affecting both sides of the body). Mixed vitiligo is grouped under non-segmental vitiligo due to a similar prognosis.

• Non-classified.

There is a strong association with thyroid disease. Screening of TS, antibodies against TPO and TG is recommended.

Biopsies are only rarely needed in cases of diagnostic difficulty but on histological analysis, absent epidermal pigment is seen, with a lack of melanocytes and a lymphocytic inflammatory infiltrate in early phases.

Because of lack of biological filter (melanin pigment), there is an increased risk of sunburn. Stigmatisation due to lesions in visible areas (face, hands) is often present leading to reduced quality of life. Depression and anxiety can occur.

The diagnosis is usually made on clinical grounds. Examination with Wood’s light can be helpful, especially in paler skin types.

The differential diagnosis includes any condition causing hypopigmentation such as pityriasis versicolor, naevus anaemicus, naevus depigmentosus, pityriasis alba, progressive macular hypomelanosis, idiopathic guttate hypomelanosis, dry skin in darker skin types, macular forms of lichen sclerosus, any cause of post-inflammatory hypopigmentation (leucodermas of different origin) or other rare, hereditary causes of hypopigmentation (e.g. piebaldism, albinism etc), and drug-induced vitiligo-like conditions.

Early treatment is critical for therapeutic success.

For patients with non-segmental vitiligo from 12 years on and with facial involvement topical ruxolitinib (a JAK1/2 inhibitor) has been approved since May 2023 in the EU. Other topical agents include corticosteroids (class II-III) and topical calcineurin inhibitors (off-label). They can be combined with targeted or whole-body narrow-band phototherapy. Phototherapy treatment courses are long. Systemic corticosteroids can be given in cases of acute or rapidly progressive disease. Surgical procedures (e. g. autologous melanocyte-keratinocyte transplants) can be considered for stable and confined lesions.

Cosmetic camouflage with make-up may give good results in certain cases.

Bleaching agents or lasers for depigmentation of residual normal skin should be considered only as an ultima ratio. Widespread.

Topical sunscreens are recommended to prevent sun damage.

Counselling/psychological support should be recommended for those patients with the psychosocial impact of the disease.