hyper hypo depigmentation, white spot disease, vitiligo
- On the one hand, hyperpigmentation, where there is an excess of melanin (hypermelanosis), and on the other
- Hypopigmentation, where there is a lack of melanin (hypomelanosis) and of which there is still the special form of depigmentation, where the melanin is completely absent.
Epidemiology
The different forms of pigment disorders occur with different frequency and in different groups of people. Freckles, for example, are more likely to be found in younger people, while age spots, on the other hand, only appear in people over 40. Melasma is found more often in women, the other disorders do not seem to prefer a particular gender. The disease classically known as a pigment disorder, white spot disease, occurs in about 0.5 to 2% of the world population. In the white population there is about one person with albinism for every 20,000 inhabitants.
Pigment disorders in children
Whereas some pigment disorders only occur in the course of life, for example through exposure of the skin to harmful UV radiation, some pigment disorders are present from birth. Most pigmentary disorders that occur in childhood or are already present from birth have no disease value and do not require therapy. In general, a distinction must be made between hyper- and hypopigmentation when distinguishing a pigment disorder.
Hyperpigmentation disorders include, for example, changes in the skin commonly known as liver spots. Moles (medically known as lentigo simplex) can be present immediately after birth or can occur in childhood. New liver spots can also appear later.
They are based on an increase in melanocytes, which are responsible for the dark color of the affected area of the skin. The same applies to café-au-lait spots, which can also be present at birth or only become visible in the first few months. These are conspicuous if more than five areas of the skin are affected by café-au-lait spots, as this can be a sign of some genetically inherited diseases.
Up to three of these pigmentation disorders can be found in 10-30% of all older children. The so-called pigment nevi, which include the Mongolian stain, are pigment disorders that sometimes occur in newborns. The Mongolian stain is a harmless accumulation of melanocytes – cells in the skin that are mainly responsible for pigmentation.
Over time, however, this change in pigmentation disappears and thus belongs to the group of reversible pigment disorders. However, other forms of pigment nevi have a certain risk of degeneration, which is why lifelong monitoring by a dermatologist is required in these cases. Freckles (ephelids) are pigment deposits in the skin, which differ from the rest of the skin by a yellowish, brownish coloration.
They are based on an increase in melanin, whereby the number of melanocytes is normal. They usually appear from the third to fifth year of life and usually decrease in intensity during the course of life. Freckles often correlate with red hair color and pale skin, since the gene responsible for freckles is also responsible for these characteristics.
In addition to hyper(over)pigmentation, there are also hypo(under)pigmentations that can be found in infancy or childhood. Genetic causes as well as acquired pigmentation disorders can occur equally. Hypopigmentation is usually accompanied by a reduced number of melanocytes or melanin and is in most cases irreversible.
Examples of hypopigmentation are albinism, white spot disease (vitiligo), Waardenburg syndrome, nevus depigmentosus and some other pigmentation disorders. In most cases of pigmentation disorders in children no therapy is required. If cosmetic therapy is desired, treatment with creams or laser treatment of the skin can be performed.
However, this should be discussed thoroughly with the doctor, as these treatments do have side effects that need to be weighed up. The causes of pigmentation disorders are at least as varied as the various clinical pictures that can trigger them and some of them have not yet been definitively clarified. In some cases, several factors must interact to bring about a change in the skin.The following can be responsible for a pigment disorder: hereditary factors, mechanical irritation (such as pressure or friction), thermal stress (heat or cold), certain medications, cosmetics or hormonal changes, such as changes in the hormone balance caused by taking the contraceptive pill (see: Pigment disorder caused by the pill) or during pregnancy.
A pigment disorder in the form of hyperpigmentation can be caused either by increased melanin production or by melanin being deposited in large quantities in the skin, both of which cause it to look darker in the affected areas. There are several triggers that can stimulate melanocytes to produce massive amounts of melanin or to multiply through cell division. These include UV radiation, hormones or special types of inflammation.
For example, there is the so-called post-inflammatory (after an inflammation) hyperpigmentation, which can be the consequence of inflammatory skin diseases and is often accompanied by psoriasis or a rash and can still be present months after the inflammation. The reason for hypopigmentation is that the melanin content is reduced, which can happen due to a decreased melanocyte count or reduced melanin production. In depigmentation, this color pigment is completely absent.
The reason for this can be a destruction of the melanocytes, which can be caused by extreme cold, X-rays, various toxic substances or even inflammation. Hypopigmentation can also be the result of a disturbed transmission of melanin to the horny cells of the epidermis, which can be caused by inflammatory processes such as psoriasis or neurodermatitis. In the case of white spot disease (vitiligo), the melanocytes are probably destroyed by an autoimmune process (i.e. by an inadequate defense reaction from the patient’s own immune system).
Albinism is a congenital disorder in which no melanocytes are formed at all. The diagnosis of a pigment disorder can be made by a physician or independently, usually by looking at affected areas, since the external appearance of pigment disorders is usually very characteristic of the individual forms. In addition, the patient’s medical history (anamnesis) must be taken, which often makes it easier to find or confirm a result. Here, for example, the family anamnesis plays an important role in order to be able to diagnose genetic diseases such as white spot disease. In case of doubt, the doctor can also take a tissue sample (biopsy) and examine it under the microscope.
