Curriculum · ENT, Ophthalmology, and Dermatology
Vitiligo
What it is
Vitiligo is an autoimmune condition which results in the loss of melanocytes and consequent depigmentation of the skin. Put the other way, it is an acquired partial to complete loss of pigmentation due to autoimmune destruction of melanocytes. It is thought to affect around 1% of the population, and symptoms typically develop by the age of 20-30 years.
The distribution pattern of the amelanotic skin lesions divides into two families:
- Generalized vitiligo: vulgaris, acrofacial and universal
- Localized vitiligo: focal and segmental
The buzzword to carry into an exam is chalk-white patches on the hands and face, or depigmented patches.
The autoimmune company it keeps
Because the destruction of melanocytes is autoimmune, vitiligo is associated with other autoimmune disorders, and the association is asked about more often than the skin itself. The core list is type 1 diabetes mellitus, Addison's disease, autoimmune thyroid disorders, pernicious anaemia and alopecia areata; Hashimoto thyroiditis is the thyroid disorder named by name, and Graves disease is named too.
The cluster runs wider than the dermatology page, because autoimmune diseases tend to cluster:
- Primary adrenal insufficiency: hyperpigmentation or vitiligo is a feature of the chronic picture, alongside fatigue, weakness and anorexia, weight loss, hypotension, hyponatremia, hyperkalemia and hypercalcemia, anemia and eosinophilia. In Addison's disease the skin signs are hyperpigmentation, especially of the palmar creases, vitiligo, loss of pubic hair in women and hypotension. The other autoimmune diseases named beside it are type 1 diabetes and Hashimoto's thyroiditis
- Autoimmune hepatitis: associated with DM-1, celiac disease, Graves, vitiligo and UC
- Pernicious anaemia from autoimmune gastritis, where autoimmune destruction of parietal cells removes the intrinsic factor required for vitamin B12 absorption in the ileum. Autoimmune thyroid disease as hypothyroidism often coexists with vitiligo, pernicious anaemia and diabetes
- Juvenile hypothyroidism, usually caused by autoimmune thyroiditis: children with Down or Turner syndrome carry an increased risk of it and of developing other autoimmune disorders, vitiligo, rheumatoid arthritis and diabetes mellitus among them
- Alopecia areata: the associated autoimmune diseases listed with it are Hashimoto thyroiditis, vitiligo and type 1 diabetes
- CVID: among the autoimmune phenomena of CVID are hemolytic anemia, thrombocytopenia, vitiligo and rheumatoid arthritis
- Gonadal dysgenesis 46XX: associated with autoimmune diseases in 18-30%: Hashimoto's thyroiditis, Addison's disease, hypoparathyroidism and vitiligo
- Scleroderma: the skin carries subcutaneous calcification over fingers, elbows and extensor forearms, and vitiligo or pigmentation
Trauma may precipitate new lesions, which is the Koebner phenomenon, also called the isomorphic response. The clinical entities that commonly display it are psoriasis, vitiligo, lichen planus, lichen niditus, cutaneous small vessel vasculitis and Still disease. It is to be distinguished from autoinoculation, the pseudo-Koebner phenomenon seen with verrucae or mollusca, and from the Wolf isotopic response, where a second skin disease appears at the site of an earlier unrelated and often healed skin disease.