Dermoscopy of vitiligo

What is vitiligo?

Vitiligo is a common acquired depigmentation of the skin due to autoimmune destruction of melanocytes. It is characterised by well-circumscribed chalky-white macules and patches. Hairs in the involved skin may be normal or white. 

The incidence of vitiligo is apparently higher in the Indian subcontinent due to its colour contrast and stigma attached to the condition.

Vitiligo is also known as as 'swetha kushta' in India.

What are the clinical features of vitiligo?

The clinical manifestations of vitiligo include depigmented macules and patches on the skin, mucous membranes, and hair. Vitiligo is asymptomatic although some patients complain of itching before the macules appear. White hairs in the involved area are associated with a poor prognosis.

Vitiligo has a tremendous impact on the social life of patients. They often have low self-esteem and are depressed, and hence avoid social gatherings. It is said that ‘vitiligo licks the skin but bites the mind’.

Vitiligo on the gluteal area

Vitiligo of the ankle

Vitiligo

What are the dermoscopic features of vitiligo?

The dermoscopic features of vitiligo include [1]:

• White structureless areas (absence of pigment network) and reduced pigment network. White structureless areas appear to ‘glow’ due to total loss of melanocytes in the epidermis
• Perilesional and perifollicular hyperpigmentation and reversed pigment network
• Starburst pattern, tapioca sago pattern (satellite lesions), micro-koebnerisation, and comet-tail appearance [2]. 

Stable vitiligo is characterised by a sharp border, white structureless areas, reduced pigment network, and perilesional and perifollicular hyperpigmentation, whereas active disease demonstrates a starburst pattern, tapioca sago pattern (satellite lesions), micro-koebnerisation and comet-tail appearance.

White structureless area 'glow' (black stars), perifollicular pigmentation (yellow arrow), reticulate pigmentation (red arrow) and perilesional hyperpigmentation (red star).

White structureless area 'glow' (red star) and perifollicular pigmentation

White structureless area 'glow' (black stars), perilesional pigmentation (yellow arrows) and satellite lesions (black arrows)

What is the dermoscopic differential diagnosis for vitiligo?

The dermoscopic differential diagnosis of vitiligo includes naevus depigmentosus, idiopathic guttate melanosis, pityriasis alba and pityriasis versicolor.

• The dermoscopy of naevus depigmentosus shows white structureless areas with a faint pigment network in the background. Glow is absent due to the presence of the network. White areas may extend peripherally.
• Like vitiligo, idiopathic guttate hypomelanosis has a glow on dermoscopy but unlike vitiligo, the white area is clearly demarcated from normal skin. Guttate hypomelanosis has amoeboid (pseudopod-like border), petaloid, feathery and nebuloid (gradually fading border) morphological variants. 
• The dermoscopy of pityriasis alba shows white structureless areas without a glow, a faint pigment network, and superficial white scales.
• The dermoscopy of pityriasis versicolor also shows white structureless areas without a glow, pigment network and white scales. Scales are prominent in the skin lines and are separated into lines when the lesion is stretched.

Naevus depigmentosus

Guttate hypomelanosis

Pityriasis alba

Pityriasis versicolor

What is the histological explanation of the dermoscopic features of vitiligo?

The histology of vitiligo shows a normal epidermis with loss of melanocytes. A normal reticulate pigment network is due to melanocytes in the rete ridges. In vitiligo, destruction of melanocytes results in loss of the pigment network resulting in the dermoscopic glow [3].