Autumn in a woman’s life can be a warm, cozy period, or a sad time of fading. Psychologists assure: everything depends on the perception of age-related changes, on how a woman treats wrinkles and spots on the skin. Melanocytes play a huge role in skin aging. They are to blame for the appearance of age-related “freckles”.

Why do melanocytes gather?

IN early age melanocytes are distributed evenly in the skin. Let us remind you: these substances are needed to protect the skin from ultraviolet radiation. The more intense the sun, the stronger the reaction; the stronger the reaction, the darker the skin.

When age-related changes begin in the body, melanocytes are localized in certain places. Most often this is the back of the hands, back, upper part breasts Often - face, legs.

On cellular level This is what happens:

• cell regeneration (restoration) slows down;
• the amount of protein changes;
• fat metabolism is disrupted;
• moisture deficiency occurs in deep layers;
• blood microflow in the capillaries slows down;
• the functioning of melanocytes is disrupted.

Not everyone experiences age-related pigmentation. The main factor is the passion for tanning. Ultraviolet radiation has a destructive effect on the skin. Cosmetologists are sure that the places where burn blisters were located are the most likely for brown spots to appear.

The most dangerous neoplasm, melanoma, originates in melanocytes. Tanning should not be taken lightly. All new moles, spots and other phenomena must be shown to a surgeon, dermatologist, or oncologist.

Uneven distribution of melanin also provokes the following changes:

• hormonal (including taking hormonal contraceptives);
• vitamin deficiency or hypervitaminosis;
• all types of dermatitis;
• mechanical, chemical damage to the skin;
• weakened immunity.

Prevention and treatment of pigmentation

1. Use of bleaching agents (daily, long-term).
2. Use of products with UV protection effect.
3. Professional procedures.
4. Destruction (removal) of cells containing melanin.

Scrub mask for pigment spots. Reminder!

Products with whitening effect

Bleaching agents include the following:

• Arbutin (inhibits melanin synthesis);
• azelaic acid (prevents the synthesis of melanin pigment);
• licorice extract;
• ascorbic acid (penetrates into the deep layers of the skin, whitens freckles and age spots);
• kojic acid (exfoliating properties);
• retinoids;
• hydroquinone (causes the death of melanocytes, gives an irreversible whitening effect, sometimes excessive; used with caution);
• low-potency corticosteroids, etc.

All these drugs should be used with caution, especially after a fresh tan, during pregnancy and breastfeeding, herpes in the acute stage, and with a predisposition to keloid scarring of the skin.

Back in the last century, the cosmetics industry successfully used mercury as one of the most effective whitening agents. But, as the scientists said, “the more we study mercury, the more toxic it becomes.” “Liquid silver” was used to treat Ivan the Terrible, who suffered from a “shameful disease.” Mercury was used to whiten the face, hands and teeth. There is a version that it was this metal, amazing in its properties, that caused the death of the mad king and many noble beauties who wanted to be proud of their snow-white skin.

Professional treatments

Attitude to professional cosmetic procedures very ambiguous. Even cosmetologists cannot come to a consensus: are they dangerous for the skin? chemical peels, lasers, etc., or harmless?

• Chemical peels. Fetinic and mandelic acid are used; retinoids. Retinoids give quick effect and require long-term rehabilitation. While acids act more gently, but require more procedures.
• Mesotherapy, or treatment of pigmentation with injections. Use glycolic acid, linoleic acid; vitamin C, emoxypine, placenta extract, multivitamins.
• Cryotherapy using liquid nitrogen. Using an applicator, the drug is applied to the stain for 10-15 seconds. Later, active peeling appears in this place, and in parallel, active regeneration of the skin occurs. After 3 weeks, the procedure can be repeated.
• Microdermabrasion, hardware peeling. Prescribed when different types pigmentation. It has serious disadvantages - the patient runs the risk of scarring, leukodermatitis, and postoperative infection. Today the method is not very popular.
• Laser technologies. Lasers of adjustable quality factor and pulse length are used. The technology is based on the ability of age spots to actively absorb laser radiation, which subsequently leads to the destruction of melanin. A fairly successful method, but due to constant exposure of the skin to sunlight, there is a risk of new pigmentation.

Video. Whitening face masks at home

Each person has their own shade skin, which is genetically determined. Normally, human skin pigmentation is determined by the following four main components:

• epidermal;
• carotenoids;
• oxygenated hemoglobin;
• deoxygenated hemoglobin.

It is melanin, located between the keratinocytes surrounding melanocytes, that is the main factor that determines skin color. In fair-skinned people, the skin most typically contains the light brown type of melanin (pheomelanin) in small quantities. And dark-skinned people have dark brown melanin (eumelanin) in large quantities. It is the ratio between pheomelanin and eumelanin that determines skin tone.

Most people experience pigmentation disorders during their lifetime. In most cases they are benign, limited and reversible. A striking example of such temporary disorders can be hyper- or hypopigmentation of the skin in inflammatory dermatoses. They exist for several months, but then completely disappear on their own. But some pigmentation disorders may be irreversible, can only be corrected with surgery, or cannot be cured.

In our article we will introduce you to the main types of skin pigmentation disorders and those diseases that are characteristic of this or that pathology.

Main types of skin pigmentation disorders

Dermatologists distinguish three main types of pigmentation disorders:

1. Leucoderma. This disorder is accompanied by hypopigmentation and is caused by a decrease or complete absence of melanin.
2. Melasma. This pigmentation is accompanied by hyperpigmentation and is caused by excess melanin deposition.
3. Gray-blue dispigmentation. This disorder occurs against the background of the presence of melanin in the skin and is accompanied by the deposition of melanin or non-melanin changes in the color of the skin.

Each of these pigmentation disorders is not an independent disease. These terms refer to those characteristic signs that can be observed on the skin of patients with various diseases, accompanied by changes in the color of the skin, hair or eyes.

Leucoderma

Depending on the causes of development, several types of leucodermas are distinguished.

Infectious leucoderma

Such pigmentation disorders are caused by various infectious diseases:

• leprosy;
• pityriasis versicolor;
• pityriasis alba;
• lichen planus.

Syphilitic leucoderma

At the secondary stage of syphilis, the patient develops skin symptoms of syphilitic leukoderma. White spots are most often localized in the form of a necklace around the neck (necklace of Venus), less often - on the arms and torso. Changes in skin pigmentation do not cause discomfort, but may not disappear for several years.

The following types of syphilitic leukoderma are distinguished:

• lace (or mesh) - white spots appear on the skin, which merge with each other and form mesh pattern, reminiscent of lace;
• marbled - characterized by weak pigmentation around the white spots;
• spotted - characterized by the appearance of multiple round or oval white spots of the same size against the background of hyperpigmentation.

Leprosy leukoderma

Leprosy is an infectious disease caused by mycobacteria Mycobacterium leprae or lepromatosis and is accompanied by lesions nervous system, skin and some other organs. Sharply defined spots appear on the patient’s skin white, which may be surrounded by a reddish rim. In the area of ​​pigmentation disorders, there is a loss of sensitivity or changes in it. Areas of compaction appear under the spots, which lead to the formation of folds.

Leucoderma in lichen versicolor

Tinea versicolor can be caused by the fungi Malassezia furfur or Pityriasis orbicularis. They affect the skin or scalp. Pathogens produce special enzymes that act on melanocytes and cause the cessation of melanin production. Because of this, white spots appear on the skin, which are especially clearly visible after tanning (these areas of the skin remain completely white). Most often, such symptoms are observed in the upper torso.

Leucoderma with lichen alba

So far, scientists have not established the reasons for the development of white lichen. With this disease, which is most often observed in children from 3 to 16 years of age (mainly in boys), white rounded areas of depigmentation appear on the skin of the cheeks, shoulders and sides of the thighs. They rise slightly above its surface and peel off almost imperceptibly. White spots become especially noticeable after sunbathing. Areas of dyspigmentation do not cause unpleasant sensations (sometimes they can itch and burn slightly). After a few months or a year, the white spots disappear on their own. In rare cases, with the chronic form of lichen alba, they can persist into adulthood.

Leukoderma in lichen planus

The reasons for the development of lichen planus are still unknown. It is assumed that this disease, accompanied by damage to the skin and mucous membranes (sometimes nails), can be caused by viruses, nervous stress or toxins. Lichen planus is more common in adults. Small shiny nodules of a dense red, brownish or bluish color appear on the patient’s skin. They are sharply limited from the surrounding areas of the skin or mucous membranes; they can merge and form plaques with a peculiar mesh pattern.

On some nodules, an umbilical indentation may be detected. Rash with red lichen is accompanied by itching, pigmentation disorders and skin atrophy. More often, such nodules appear on the inner surface of the thighs, wrist joints, popliteal fossae, elbow bends or in the ankle area. Can be observed on the genitals and oral mucosa. The rash goes away on its own after a few weeks or months and recurs over many years.

Medicinal leucoderma

This pigmentation disorder develops due to toxic poisoning with certain drugs (for example, steroids or furatsilin).

Professional leucoderma

In people of certain professions, a disorder of skin pigmentation occurs, which is provoked by constant contact with certain toxic substances. Such toxic compounds can act directly on the skin or be ingested.

Congenital leukoderma

Such pigmentation disorders are caused by hereditary diseases (Ziprowski-Margolis, Wulff, Waardenburg syndromes). Congenital forms of leukoderma include a disease such as, but so far scientists have not identified the carrier gene of this disease, and this pathology is considered as immune leukoderma.

Albinism

A group of these hereditary diseases of the melanin pigment system is accompanied by a decrease in the number of melanocytes and low levels of melanin. There are 10 forms of albinism. In some types of such pigmentation disorders, the skin, hair and eyes are involved in the pathological process, while in others - only the eyes. All forms of albinism cannot be treated, and symptoms remain localized throughout the patient’s life.

The main symptoms of these diseases are the following:

• hypo- or depigmentation of the skin, hair and eyes;
• vulnerability of the skin to ultraviolet rays;
• photophobia;
• decreased visual acuity;
• nystagmus.

Tuberous sclerosis

This disease is inherited in an autosomal dominant manner and is accompanied by the formation of plaques and tumors on the skin and internal organs(including on the brain). On the skin of such patients (usually in the buttocks and torso) there are light spots, the shape of which resembles confetti or leaves. They can be observed already at the time of birth or appear up to a year (or up to 2-3 years). With age, their number increases.

Already in infancy or childhood white strands of hair, eyebrows or eyelashes appear. Next, the patient develops tumors: angiofibromas, fibrous plaques, periungual fibromas “shagreen skin”. When the brain is damaged, cortical tubera and subependymal nodes develop, and in the internal organs, renal cysts, renal and liver hematomas, retinal tumors and cardiac rhabdomyomas can be found. Tuberous sclerosis is accompanied by mental retardation and epilepsy.

Immune leucoderma

These pigmentation disorders are caused when the immune system, for unknown reasons, attacks an area of ​​skin and destroys melanocytes.

Vitiligo

This disease can occur in people of any age and gender. Such patients develop milky white or light pink spots on the skin, which in most cases are localized on the hands, knees or face. They can increase in size and merge. The hair in the spot area becomes discolored. White spots do not cause any discomfort and do not peel off.

Halo nevus

These nevi are most often observed in children or adolescents and are pinkish or brown round spots that are slightly raised above the skin and surrounded by a border of white skin. Their sizes reach 4-5 mm, and the size of the depigmented rim can be 2-3 times larger than the formation itself. Most often, Halo nevi are located on the arms or torso, less often on the face. Similar formations can be observed in patients with vitiligo. The spots may disappear on their own and in most cases do not require treatment.

Post-inflammatory leucoderma

This pigmentation disorder can develop after skin rashes, which are observed in some inflammatory skin diseases (burns, psoriasis, etc.). The appearance of white spots is explained by the fact that less melanin accumulates in areas of the skin covered with crusts and scales, and more accumulates in the healthy tissues surrounding them.

Melasma

Depending on the causes of development, several types of melasma (melanoses) are distinguished.

Melasnderemia in diseases of internal organs

Severe chronic diseases can lead to the development of the following melasma:

• uremic melanosis - develops with;
• endocrine melanosis – develops with dysfunction of the pituitary gland, adrenal glands and other endocrine glands;
• hepatic melanosis – develops in severe liver pathologies (cirrhosis, liver failure, etc.);
• cachectic melanosis – develops in severe forms of tuberculosis.

Toxic reticular melanosis

This pathology develops with frequent contact with machine oil, resins, tar, coal, oil and lubricants. As a result of chronic poisoning, the following symptoms appear:

• redness of the face, forearms and neck, accompanied by mild itching or fever;
• the appearance of reticular hyperpigmentation of a red or bluish-slate color with clear boundaries;
• the intensity of pigmentation increases and they become diffuse;
• hyperkeratosis develops in the area of ​​pigmentation, and areas of skin folding, telangiectasia and areas of peeling appear.

In addition to skin manifestations, patients complain of a violation general well-being: loss of appetite, weight loss, malaise, etc.

Dubreuil's precancerous melanosis

This hyperpigmentation is more common in women over 50 years of age. The patient develops the following symptoms:

• an irregularly shaped pigment spot with a diameter of 2-6 cm appears on the face, chest or hands;
• the spot is unevenly colored with areas of brown, gray, black and bluish color;
• the skin in the area of ​​the spot is less elastic, and the skin pattern on it is rougher.

Becker's melanosis

This disease is more often observed in men 20-30 years old. A brown spot of irregular shape, 10-50 cm in size, appears on the patient’s body. Most often it is located on the torso, less often in the face, neck or pelvis. Many patients experience significant hair growth in the area of ​​the spot. The skin becomes rough, thickened and wrinkled.

Papillary pigmentary dystrophy of the skin (acanthosis nigricans)

This hyperpigmentation is accompanied by the appearance of brown, velvety spots in the armpits or other parts of the body. Acanthosis nigricans can accompany some cancers or be congenital and benign (with pituitary adenoma, Addison's disease, etc.).

Mastocytosis (urticaria pigmentosa)

This hyperpigmentation is accompanied by the appearance of multiple round papules and irregularly shaped red or yellow spots. brown. Their size reaches 3-8 mm. The spots may merge. The rash is sometimes accompanied by itching. When scratched or rubbed they become swollen. This hereditary disease is benign in most cases and first appears in early childhood. After a few years it may disappear spontaneously.

Coffee stain (or Nevus spilus)

With such hyperpigmentation, brown single or multiple spots with clear boundaries and uniform color appear on the skin. Their shade can vary from light to dark. The spots can be located on any part of the skin, but never appear on the mucous membranes. Nevus spilus is detected immediately after birth or in early childhood, and its size increases as the child grows.

Chloasma

Such hyperpigmentation is more common in women and is caused by hormonal imbalances or changes during pregnancy and menopause. They most often appear on the face as irregularly shaped yellowish-brown spots and may fade or disappear in the winter.

Lentigo

Such pigmentation disorders are observed in some hereditary syndromes. Limited small and flat hyperpigmented elements are formed on the skin.

Moynahan syndrome (LEOPARD)

This pigmentation disorder is observed in young people. It is accompanied by the rapid appearance of hundreds of lentigo spots on the skin of the face, trunk and limbs.

Freckles

Such pigmentation disorders are more often observed in fair-haired people. They appear in childhood or adolescence and represent age spots irregularly shaped, which do not rise above the skin and are located symmetrically. The color of freckles can range from yellowish to brown, and the color intensifies after exposure to ultraviolet rays.

Poikiloderma

Such pigmentation disorders manifest themselves in the form of dystrophic changes in the skin, manifested by reticular brown hyperpigmentation, which alternates with areas of telangiectasia and skin atrophy. The disease can be congenital or acquired.

Peutz-Jeghers syndrome

With this disorder of pigmentation, common lentigines appear on the lips, mucous membranes of the mouth and eyelids. Polyps appear in the intestinal lumen (usually the small intestine) and manifest as bleeding, diarrhea, intussusception, or obstruction. Over time, they can degenerate into cancerous tumors.

Recklinghausen's disease

With such pigmentation disorders, which are observed with neurophyromatosis, coffee spots and freckle-like elements of a brown tint appear in the axillary and groin areas. Their diameter can reach several millimeters or centimeters. The spots are present from birth or appear in the first year of life.

Blue-gray dispigmentation

Depending on the causes of development, there are several types of gray-blue dispigmentation:

1. Caused by an increase in the number of melanocytes. Such pigmentation disorders include: nevus of Ota, nevus of Ito and Mongolian spot. Nevus of Ota is located on the face and is a patch of rich brown, violet-brown or blue-black color, which often extends into the periorbital area and extends to the temples, forehead, structures of the eye, nose and periorbital areas of the cheeks. Nevus is more often observed in women and appears in childhood or at a young age. More typical for Asians. Nevus of Ito differs from nevus of Ota only in location. It is localized in the neck and shoulders. The Mongolian spot is observed from birth and manifests itself in the form of gray-blue pigmentation of the skin in the sacrum and lumbar region. By 4-5 years, the spot disappears on its own. This pathology is more common among people of the Mongoloid and Negroid races.
2. Non-melanin dyspigmentation caused by metabolic disorders. Such pigmentation disorders include ochronosis. This rare hereditary pathology is accompanied by deficiency and accumulation of homogentisic acid oxidase in the connective tissue. Such disorders lead to a change in skin color, and it acquires a dark brown or bluish-gray tint. Pigmentation disorders are most often observed in the area of ​​the ears, nail plates of the fingers, tip of the nose, sclera and dorsum of the hands. The disease is accompanied by damage to the joints.
3. Caused by thermal effects. Such pigmentation disorders include thermal erythema. The disease is usually provoked frequent use heating mattresses, mats and blankets. The affected areas of the skin acquire a gray-blue tint and subsequently scars and persistent areas of hyperpigmentation may appear on them. Patients experience a burning sensation. The lesion may be accompanied by erythema and desquamation.
4. For fixed drug rashes. Such disorders are caused by taking medications and are accompanied by the appearance of red-brown or gray-blue spots that appear every time the drug is taken and are localized in the same place. Initially, the spot is swollen and inflamed. It peels off and may form a blister. After the inflammation is eliminated, an area of ​​hyperpigmentation appears on the skin. Fixed drug rashes are most often caused by taking salicylates, barbiturates, tetracyclines, or phenolphthalein. After discontinuation of the drugs, dyspigmentation disappears.
5. Caused by the accumulation of heavy metals. Such pigmentation disorders are caused by deposits of gold, silver, arsenic, mercury or bismuth in the layers of the skin. With the toxic effects of silver, mercury or bismuth, the skin, nails and mucous membranes turn gray-blue. Chrysoderma develops with the introduction of gold-containing drugs and is accompanied by brown coloring of the skin. Such dyspigmentation can be caused by taking the following drugs: chloroquine, clofazimine, amiadrone, busulfan, chlorpromazine, bleomycin, trifluoroperazine, zidovudine, minocycline and thioridazine.

The manifestations of pigmentation disorders are extremely varied and can be caused by various reasons. Make the correct diagnosis and prescribe effective treatment Only an experienced dermatologist can treat such skin pathologies. To eliminate them, therapeutic and surgical techniques can be used, and some of them do not require treatment or go away on their own.

Disorders of the melanocyte system: hypomelanosis, etc. hypermelanosis

Violation of melanin pigmentation indicates diseases of other organ systems (Tables 51-1 and 51-2), they can be divided into hypomelanosis (reduced content or absence of melanin in the dermis, leukoderma) and hypermelanosis (increased amount of melanin in the epidermis or dermis). In general, hypomelanoses are caused by damage in one or more parts of the melanin transformation chain, for example, the absence of melanocytes, disruption of the formation of normal melanosomes or their transport to keratinocytes. Hypermelanosis, in turn, is divided into epidermal pigment disorders, characterized by a brown color, and dermal (blue, bluish-gray, gray color). Brown hypermelanosis (melanoderma) is associated with an increase in melanin content in the epidermis as a result of increased melanocyte activity, an increase in the number of secretory melanocytes, the number of melanosomes or their size. Bluish-gray hypermelanoses (ceruloderma, blue skin) are similar to false tattoo melanin and are explained by the presence of melanin in the dermis, in ectopic dermal melanocytes or dermal macrophages, which, as a result of the Tyndol effect, give the skin a characteristic gray, blue-gray or blue color. A similar skin color can be determined by other factors not related to melanin, ochronosis, tattoos, or medicines(aminazine, amiodarone, minocycline), deposition of certain foreign substances in the dermis.

Table 51-1. Pigmentation changes as diagnostic signs in therapy

Table 51-2. Melanin pigmentation disorder

1 Pigmentation disorders or the conditions in which they occur are also included.

2 Gray, blue-gray, or blue color is determined by the presence of dermal melanocytes or phagocytosed melanin in the dermis.

3 The area of ​​pigmentation change is limited.

4 The complete disappearance of pigment in the skin and hair is possible.

5 Loss of pigment is usually partial (hypomelanosis); When examined using a Wood's lamp, it is revealed that the altered areas of the skin are not completely devoid of pigment (amelanosis), which happens with vitiligo.

6 Pigmentation changes are diffuse, not limited, and have no defined edges.

7 Reduced amount of pigment in the iris.

8 Reduced amount of pigment in hair.

9 Pigmentation changes may be diffuse or limited. 10 Idiopathic or pregnancy-related factors. 11 Gray or red hair. 12 Reduced number of melanocytes.

13 Areas of brown color may alternate with areas of gray-blue and blue. 14 Re-growing hair is white,

Recognition of limited hypomelanosis (white spots), gray, gray-blue or blue hypermelanosis usually does not cause difficulties. In case of mild hypomelanosis in a patient with very fair or untanned skin, its changes may not be distinct; diagnosis is facilitated by dark light examination (Wood's lamp, see Chapter 47), which enhances the contrast between areas of skin with altered epidermal pigmentation and healthy, but differences between healthy skin and areas of increased dermal pigmentation. It is often difficult to differentiate diffuse brown hyperpigmentation (for example, in Addison's disease) or diffuse hypomelanosis (in albinism) from normal pigmentation due to its wide range of fluctuations in healthy people. Diffuse changes in skin color may be subtle; often the patient himself is not aware of an unusual, inexplicable, gradually progressive darkening of the skin, such as a persistent summer tan. The degree of hypermelanosis is related to the patient’s initial skin color. With Addison's disease, a person from the Mediterranean (for example, residents of Italy, France or Spain) may have intensely pigmented skin, and a person with fair skin Only a minimal degree of hypermelanosis may develop. Changes in pigmentation in the mucous membranes and certain areas, such as the axillae and palmar surfaces, are usually easier to detect than generalized brown hyperpigmentation.

Genetic disorders of melanin metabolism. Patients with pigmentation disorders may complain of general or patchy darkening of the skin, the appearance of “white” or “ birthmarks"(see Table 51-1), others experience deafness, iritis, seizures, and changes in pigmentation are random. The analysis below is based, however, on etiological factors rather than on symptomatology.

Cutaneous-ocular albinism is an autosomal recessive trait and is characterized by congenital uniform hypomelanosis of the skin and hair. Cases of cutaneous albinism alone do not occur, but ocular albinism in the presence of normal or minimally changed skin has been reported. Classic signs of ocular-cutaneous albinism are pronounced hypomelanosis or amelanosis of the skin, white or almost white hair, photophobia, nystagmus, hypopigmented fundus, and translucent iris. This type of albinism can be classified depending on the presence or absence of tyrosinase in the follicles of plucked hair from the scalp (hair follicle incubation reaction). Hair follicles healthy person darken when incubated with tyrosine. With cutaneous-ocular albinism, they can also sometimes darken under these conditions (tyrosinase-positive albinism), in other cases this effect is absent (tyrosinase-negative albinism).

The two types of albinism are known to have separate gene loci. In ocular-cutaneous albinism, melanocytes are detected, but the formation of melanosomes is interrupted in the early stages, so few mature melanosomes are found in the skin and hair of albinos. The existing tyrosinase is functionally defective; it can provide the conversion of tyrosine to DOPA. Other variants of ocular cutaneous albinism include yellow mutants, Hermansky-Pudlak syndrome (hemorrhagic diathesis due to an increase in the number of abnormal platelets) and Chediak-Higashi syndrome (recurrent infections, hematological and neurological disorders, early death in lymphoma). Melanin deficiency in ocular-cutaneous albinism has two serious consequences for humans: decreased visual acuity and a high degree of intolerance sunlight. The high sensitivity of a person with albinism to ultraviolet rays often leads to the development of cancer in exposed areas of the skin. By the third 10th birthday, almost all albinos living in the tropics develop actinic keratoses or skin cancer. Therefore, they should use effective topical sun protection during the day and avoid sun exposure whenever possible (see Chapter 52).

Congenital diffuse attenuation of pigmentation syndrome in combination with immunodeficiency has been reported. It is accompanied by splenomegaly, neutropenia, thrombocytopenia and impaired T-helper cell function.

Phenylketonuria is a disorder of phenylalanine metabolism, inherited as an autosomal recessive trait, in which a single link in the chain of conversion of phenylalanine to tyrosine is blocked. This weakens the pigmentation of the skin, hair and iris. The intensity of pigmentation of hair, which is characterized by coloration from very light to dark brown, should be assessed only by comparison with its intensity in siblings, descendants of the same parents. Melanocytes are not changed, but the set of melanosomes is not complete. Insufficient melanin formation is due to the fact that excess phenylalanine and its metabolites in serum and extracellular fluid acts as a competitive inhibitor of tyrosinase, blocking melanin synthesis.

Vitiligo, an idiopathically acquired limited hypomelanosis, is a familial disease in 30% of cases, in which amelanotic spots gradually increase in size (Table 51-3). In this case, a local segmental (within one or more dermatomes) or generalized distribution of spots is noted. In some cases, they spread so much that almost all of the skin turns white. In typical cases, vitiligo spots are localized on the extensor surfaces, in places of bone protrusions (elbow, knee joints), around small joints of the hand, around the eyes and mouth. The lower back, armpits, and wrists may also be involved in the process. It often spreads to the skin of the genitals, palmar and plantar surfaces. In typical cases, vitiligo spots gradually increase in a centrifugal direction, and new ones appear. In less than 30% of patients, areas of mild repigmentation may spontaneously appear, especially in exposed areas of the skin. The hair in the vitiligo patch area is usually white, but can be a normal color. Most people with vitiligo are generally healthy, but others have an increased incidence of thyroid disease, diabetes mellitus, Addison's disease, and pernicious anemia. Indeed, hyperthyroidism, thyroiditis, hypothyroidism and non-thyrotoxic goiter as a typical concomitant disease are found in vitiligo in people over 50 years of age, this especially applies to hypothyroidism. There are reports of syndromes with multiple endocrinopathies, hyperthyroidism, hypoparathyroidism, Addison's disease, chronic candidiasis of the mucous membranes and skin, and alopecia areata. More than 10% of patients may develop iritis. The question of the pathogenesis of vitiligo has not been resolved; according to classical ideas, it is associated with the destruction of melanocytes, toxic melanin precursors or lymphocytes. According to some reports, antibodies to normal melanocytes are detected in vitiligo.

Table 51-3. Disorders in localized hypomelanoses such as vitiligo