Symptoms
Usually beginning before the age of 20, the appearance of white patches is completely asymptomatic; the foci themselves exhibit neither itching nor scaling, are often bizarrely configured, and occasionally have darker pigmentation around the edges. A hereditary predisposition exists in one third (approx. 35%) of affected individuals. The spread is extremely variable, it can remain with a few smaller white areas or a generalized spread over large parts of the body surface can occur. Vitiligo often begins in sun-exposed areas, such as the face (especially eyelids, mouth area) and hands, as well as in the genital area. Poliosis refers to vitiligo of the scalp with whitening of the hair, eyebrows or eyelashes. Vitiligo can be accompanied by hearing disorders, the cause of which is also not yet fully understood. The frequent occurrence of vitiligo in connection with various autoimmune diseases suggests an erroneous reaction of the immune system with destruction of the body’s own pigment cells. In addition, a defective enzyme (catalase) in the pigment cells could be responsible for their destruction and explain the familial accumulation. Vitiligo is commonly found in thyroid diseases (Hashimoto’s thyroiditis, Graves’ disease), type I diabetes mellitus, circular hair loss, or other diseases in which autoantibodies are formed.
Classification
Three types are distinguished: 1. Segmental vitiligo begins in childhood and develops rapidly. It is rarely accompanied by other autoimmune diseases and is characterized mainly by its white symmetrical patches. Several skin segments (dermatomes) are affected by the depigmentation. It occurs in 5% of patients. 2. focal vitiligo usually manifests at a later stage, but it can also appear in childhood. It develops progressively and gradually and occurs in about 15% of patients. Characteristic is the unilateral asymmetric distribution of the spots, which usually affect only one skin segment. Rarely, two or more segments may be involved. Generalized vitiligo occurs in about 80% of patients and is the most common form. It often shows a more rapid progression and is often associated with autoimmune diseases such as thyroid disease.
Causes and triggers
The causes of the disease have not been determined to date; it is possible that various causal factors exist that individually or together lead to the destruction of pigment cells (melanocytes). Various hypotheses regarding the development of vitiligo are described in the literature:
- Genetic predisposition (disruption of pigment production by altered enzymes) with self-destruction of melanocytes.
- Autoimmunological processes with emergence of immune cells that attack the body’s own pigment cells.
- Stress factors, sunburn, toxic radicals such as hydrogen peroxide.
Complications
Vitiligo is not painful or dangerous, but it can be a psychosocial burden. Lack of UV protection in vitiligo areas promotes sunburns and the development of skin cancer, so the affected skin areas must be well protected from sunlight with a sunscreen or clothing.
Diagnosis
Diagnosis is made under medical treatment and is based on dermatologic examinations and by ruling out other causes. Differential diagnosis can delineate several pigmentary disorders in which there is either a deficiency of melanocytes or a decrease in melanin.
Nonpharmacologic treatment
Vitiligo is now most commonly treated cosmetically with skin-staining agents and self-tanning agents (e.g., dihydroxyacetone) (camouflage). These are used to superficially cover the depigmented areas of skin. The treatment of first choice for patients with severe vitiligo is the so-called narrow band UVB phototherapy. It is safe and also suitable for children. The affected skin regions are irradiated with ultraviolet light in the range of 311 nm. In some patients, repigmentation of more than 75% has been achieved within one year. Another type of phototherapy consists of a combination of orally administered psoralen and phototherapy with ultraviolet irradiation (PUVA therapy). It lasts at least 2-3 months and requires around 200 treatments.Complete repigmentation occurs in only about 15-20% of those affected. In the so-called PUVA water bath, patients lie for 15 minutes in a bathtub filled with psoralen water, which promotes the absorption of the active ingredient into the skin. This is followed by phototherapy.
Drug treatment
Topical glucocorticoids, topical calcineurin inhibitors (tacrolimus, pimecrolimus), and vitamin D analogs (calcipotriol, tacalcitol) in particular are used for drug therapy of vitiligo. Compared to phototherapy, they cause a more blurred repigmentation, which occurs faster but is less stable. Therefore, drug therapy is often combined with phototherapy. Afamelanotide stimulates pigment formation and is currently under clinical investigation.
