Vitiligo

Vitiligo is an acquired, chronic loss of melanocytes in areas of the epidermis that results in complete depigmentation of the affected skin. It results in a white appearance of the skin and occasionally hair.

Vitiligo is observed in 0.4-2% of the worldwide population, with a peak incidence between 10-30 years. It affects males and females equally.

Pathophysiology

In vitiligo, there is cytotoxic T-cell mediated destruction of melanocytes in the epidermis. Melanocytes are responsible for producing melanin, which is the pigment that protects the skin from toxic UV radiation. It is believed that there are some abnormalities in the melanocytes that initiate an innate immune response against them. Such abnormalities include elevated ROS and generation of pro-inflammatory responses. Once the T cells are activated, they destroy the melanocytes. The lack of melanin is observed as white macules on the skin.

It was previously believed that there was a neuronal cause for vitiligo (specifically for segmental vitiligo). In this theory it was believed that neurochemical mediators from the nerve endings located in the epidermis became toxic to melanocytes. However, this is now less relevant as the autoimmune and inflammatory hypothesis is more likely for both segmental and non-segmental vitiligo.

Other contributing factors to the aetiology:

• Genetic predisposition - family history is observed in 50% of cases.
• Autoimmune disease - the strongest being autoimmune thyroid disease (Grave's or Hashimoto's)
• Other disorders associated include: type 1 diabetes mellitus, psoriasis, IBD, alopecia areata, pernicious anaemia Addison's disease.

🔢 Classification

Vitiligo can be divided into 2 types:

1. Non-segmental vitiligo
2. Segmental vitiligo

Non-segmental vitiligo:

This is the more common form of vitiligo as it affects 85-90% of individuals with vitiligo. The distribution is not dermatomal. It most frequently affects the face, genitals, hands and fingers.

We can sub-classify non-segmental vitiligo even further:

1. Focal vitiligo - this is when the vitiligo affects only a small, isolated area without any obvious pattern of distribution. The lesion does not progress or change after a period of 1-2 years.
2. Acrofacial vitiligo - “acro” refers to the extremities. Therefore, in this subtype it affects the face, head, hands and feet mainly. A distinct feature is depigmentation of the distal fingers and around the facial orifices (“lip-tip” distribution).
3. Mucosal vitiligo - this subtype affects the oral and/or genital mucosa.
4. Generalised vitiligo - this is when there is a random distribution that may affect the entire body. It most commonly affects areas subject to pressure, friction, trauma.
5. Vitiligo universalis - this is when 80-90% of the entire body is affected.
6. Follicular vitiligo - hairs are depigmented.
7. Mixed vitiligo - a mixture of segmental and non-segmental forms co-exist.

Segmental vitiligo:

Also known as unilateral vitiligo - this is when the vitiligo has a dermatomal distribution (and usually unilaterally). The patches usually respect the midline and do not cross (some lesions may partly cross though). It also may more commonly affect hair follicles, causing patches of white hair (leukotrichia). It may sometimes affect larger areas that are demarcated by Blaschko’s lines (lines that represent the growth pattern of the skin).

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Fitzpatrick scale

This is a scale from 1-6 that classifies an individual’s complexion in relation to their tolerance of sunlight.

Type	Features	Tolerance
Type I	Pale white skin.	Always burns. Never tans.
Type II	White skin.	Burns easily. Tans minimally.
Type III	Cream white/fair skin	Burns moderately. Tans gradually and uniformly.
Type IV	Light brown skin	Burns minimally. Tans easily.
Type V	Dark brown skin	Rarely burns. Tans very easily.
Type VI	Deeply pigmented dark brown-black skin	Never burns. Tans very easily.

😷 Presentation

• Acral and periorificial depigmentation
• Perianal and genital depigmentation
• Recent cutaneous trauma - trauma may be implicated in the appearance of new vitiligo or the spread of existing areas. Physical trauma (ie surgical incisions and friction) and sunburn have been widely described as triggers (Koebner's phenomenon).
• Localised sunburn pain
• Enhancement and fluorescence with UV-A exposure - Wood's lamp accentuates the contrast between affected and unaffected skin
• Halo naevus - a mole with a white ring around it.
• Depigmentation of the retina - may also occur.
• Leukotrichia

🔍 Investigations

This is a clinical diagnosis based on the clinical findings. There are some tests to help confirm the diagnosis:

• Wood's lamp - accentuates the difference between affected and unaffected areas
• Skin biopsy - rarely needed
• Dermoscopy - a characteristic perilesional hyperpigmentation and telangiectasia.

Once vitiligo is confirmed, we can do some tests to look for associated conditions, such as TFT's and autoimmune antibodies

🧰 Management

1. 🥇 Topical therapies
1. Topical steroids [betamethasone, mometasone, etc]
2. Topical calcineurin inhibitors [tacrolimus, etc]
2. 🥈 Phototherapy
1. Narrowband UV-B phototherapy
2. PUVA phototherapy - has a higher risk of phototoxicity
3. 🥉 Surgery
1. Split-thickness skin grafts
2. Punch grafts

For widespread vitiligo:

1. 🥇 Phototherapy
2. 🥈 Systemic corticosteroids
3. 🥉 Surgery (same options as above)
4. Depigmentation therapy [topical monobenzone] - could be considered as a last option