Leukoderma is a polyethological dermatological condition characterized by a violation of the formation and accumulation or accelerated destruction of pigment in certain areas of the body. It is manifested by the presence of discolored areas of the skin. The size, number and localization of the sites depend on the causes of the disorder. The diagnosis of leukoderma is based on the results of a dermatologist’s examination and a general examination of the patient’s body, conducted to identify hidden pathologies. In some cases, a biopsy of tissues from the affected areas may be required. Treatment tactics depend on the etiology of this condition, both specific therapy of the provoking disease and supportive measures in the form of vitamin therapy and UV irradiation are possible.
Leukoderma is not a separate skin disease, it is a symptom indicating a general or local violation of pigment metabolism. The condition has been known since ancient times, in some cultures patients with similar skin changes were recognized as marked by the gods. Leukoderma is a very common dermatological pathology, according to some data, from 5 to 8% of the world’s population suffers from its various forms. It can be either an acquired condition that arose as a result of a certain lifestyle of a person or the impact of various environmental factors on his body, or congenital, genetically determined. The latter type is characterized by special complexity in the treatment process and often worries the patient already in early childhood. The sexual distribution of the leukoderm depends on the type and form of pathology. Some conditions occur only in men (hereditary varieties linked to the X chromosome), others can equally often affect persons of both sexes or occur somewhat more often in women.
The shade of a person’s skin depends on the presence of several pigments in it, the main of which is melanin. The rate of formation of this compound depends on two factors – the presence of tyrosine in the body, which serves as a substrate for the formation of melanin, and the processing enzyme tyrosinase. With albinism, which is considered by some dermatologists as an extreme variant of the leukoderm, there are defects in the structure of tyrosinase. The enzyme does not work, which causes the absence of melanin synthesis. In some forms of leukoderma, a similar process is observed – the enzyme is disrupted, the pigment is not synthesized, as a result, discolored skin areas appear.
There is another mechanism of hypopigmentation in this dermatological condition. Melanin should not only be synthesized, but deposited in special cellular inclusions – melanosomes. There are factors of exogenous and endogenous nature that complicate this process. Under their influence, with normal or even increased synthesis of melanin, pigment is not deposited in certain areas of the skin, which leads to the appearance of foci of leukoderma. A variant of this process may be the selective death of skin melanocytes caused by infectious agents, immunological disorders or exposure to certain chemicals. Due to the increased rate of decay of pigment cells, their timely replacement does not occur, which also provokes the appearance of symptoms of leukoderma.
A huge number of various pathological conditions and adverse factors can lead to the above violations. Most often, leukoderma occurs due to certain infectious diseases (syphilis, leprosy, certain dermatomycosis), autoimmune conditions (systemic lupus erythematosus, scleroderma), genetic pathologies (Wolfe’s disease, Vanderburg, etc.). In addition, there are forms of so-called professional leukoderma provoked by exposure to certain industrial chemicals on the body. Vitiligo and idiopathic forms of pathology are usually isolated separately. In addition, some worm infestations, immune disorders and endocrine disorders can lead to the development of leukoderma.
The modern classification of leukoderma in dermatology is based on the etiology of this condition. However, even the generally accepted list of varieties cannot cover absolutely all forms of pathology. Because of this, idiopathic leukoderm is isolated into a separate type, referring to it all forms and varieties of the condition with an unknown cause. This classification most fully and objectively divides the various groups of leukoderma for the reasons of their appearance. The convenience of classification also lies in the fact that leukoderms belonging to a certain group are characterized by similarity of clinical symptoms – this allows the dermatologist to determine approximately the list of possible etiological factors only by the appearance of the patient. Most often , the following types of leukoderma are detected in patients:
- Infectious leukoderma is hypochromia caused by exposure to various microorganisms on the skin, which can either directly affect melanocytes, or disrupt local metabolism in tissues so much that the synthesis and accumulation of pigment in them is difficult. This type includes syphilitic and leprous leukoderma, as well as hypopigmentation due to various forms of lichen.
- Immune leukoderma – in this group, researchers include vitiligo and some other autoimmune conditions (scleroderma, lupus), which may be accompanied by a violation of skin pigmentation. The causes of immune leukoderma also become immunological disorders that occur against the background of worm infestations. The unifying factor is the defeat of melanocytes by their own immune system.
- Toxic leukoderma is caused by local or general exposure to certain chemicals, including medications. This group includes the so-called occupational hypochromia, which occurs in employees of certain chemical industries with prolonged exposure to industrial toxins.
- Congenital leukoderma has genetic causes or (less often) is caused by an intrauterine lesion. It is characterized by a variety of symptoms, often in addition to skin disorders, patients have malformations and other disorders.
- Post-inflammatory leukoderma often occurs against the background of scarring after burns, as well as with long-term inflammatory skin diseases (for example, eczema).
- Idiopathic leukoderma includes all forms of pathology with undetected or unclear causes.
The main manifestation of leukoderma is a violation of pigmentation of the skin on various parts of the body. The nature of pigmentation disorders varies depending on the form and causes of the condition. So, with infectious syphilitic leukoderma, skin discoloration occurs mainly on the neck, trunk, and sometimes the face and can have three clinical forms: reticulated, marbled and spotted. In the first case, depigmentation sites consist of many small fibrous foci resembling lace, in the second – of whitish dots with indistinct contours that tend to merge. Spotted syphilitic leukoderma is characterized by the formation of separate round foci of hypochromia with clear contours and almost the same size.
Leprous leukoderma often occurs on the arms, thighs, back and buttocks. Its peculiarity is the formation of round lesions with clear boundaries. Foci after their appearance can remain unchanged for many years. Immune forms of hypochromia that develop with systemic lupus erythematosus, scleroderma and helminthic invasion are often accompanied not only by focal loss of pigment, but also by peeling or atrophy of the skin. With the correct treatment of infectious or autoimmune leukoderma, the severity of skin manifestations decreases, since the factor that has a negative effect on melanocytes or pigment metabolism disappears. A similar pattern is observed in the case of chemical or toxigenic hypochromia – often the central element of the treatment of these forms is the elimination of the provoking factor, which in itself allows to reduce the severity of skin manifestations.
Congenital forms of leukoderma have a variety of symptoms, which are largely determined by the underlying disease. Skin manifestations (depigmentation foci of various sizes and shapes) can be combined with disorders from other organs and systems. Post-inflammatory leukoderma is characterized by the appearance of hypochromia in those areas of the skin that have been burned, psoriasis or seborrhea. Often, scarring changes can be detected in the center of the focus with reduced pigmentation. The localization of pigmented disorders depends on the location of previous inflammatory skin lesions. With these forms of leukoderma, as well as with vitiligo, the restoration of the normal color of the skin can be very difficult, violations persist for many years.
Leukoderma is quite easy to determine during a routine examination of the patient’s skin, however, a whole range of different clinical studies may be required to find out its causes. When examining the patient’s skin, depigmentation areas of various shapes, sizes and localization are revealed, in some cases the foci are surrounded by a rim of hyperpigmentation (a compensatory reaction of the body). If the infectious nature of the leukoderm is suspected, a general blood test is performed, in which non-specific signs of inflammation (leukocytosis, increased ESR) can be determined. Eosinophilia may indicate the presence of a helminthic invasion. Serological tests can also be prescribed to determine the pathogen: the Wasserman reaction, a test for the presence of leprosy, and others.
By studying the main indicators of the patient’s blood and some diagnostic tests, it is possible to identify not only inflammatory, but also immune leukoderma. For example, in lupus, the presence of antinuclear antibodies is determined. An important role in the diagnosis of leukoderma is played by interviewing the patient and a thorough study of the anamnesis, since with toxigenic and post-inflammatory forms of this dermatological condition, it is the previous diseases that most often cause pigmentation abnormalities. For a more accurate determination of the leukoderm and its differentiation from some forms of lichen, an ultraviolet Wood lamp is used.
In controversial cases, skin biopsy from foci of reduced pigmentation and its histological examination may be resorted to. Depending on the form and causes of leukoderma, signs of inflammation, scar tissue, edema of the dermis or changes in the epidermis may be detected in the foci. In the most common cases of depigmentation, melanocyte anomalies are usually noted – they are either completely absent or have structural changes (low number of melanosomes, deformations of processes). In some congenital forms of leukoderma, genetic tests are used.
Leukoderma therapy is reduced to eliminating the causes that led to the violation of skin pigmentation. In infectious forms, antibiotics are used, immunosuppressive and cytostatic agents are used for autoimmune pathology, anthelmintic drugs are prescribed for helminthic invasions. With toxic leukoderma, special treatment may not be required, in some cases it is sufficient to ensure that the patient stops contact with the toxic substance. This is possible by changing the type of activity (when working in chemical industries) or canceling (replacing) some medicines. The forms of leukoderma caused by hereditary factors, as well as vitiligo, are the most difficult to treat – with the latter, some specialists practice transplanting the patient’s normally pigmented skin taken from another part of the body to foci of hypochromatosis.
Maintenance therapy can significantly improve the condition of the patient’s skin and accelerate the restoration of normal pigmentation. Prescribe general and local forms of vitamins A, E, PP and group B, vitamin and mineral complexes containing zinc and copper. According to some data, the enrichment of the diet with tyrosine also helps to reduce the symptoms of leukoderma, therefore, eggs, seafood, liver, oatmeal and buckwheat should be present in the diet of patients. Of the specific techniques used in dermatology, PUVA therapy is used – treatment of the skin with special photoactive substances followed by ultraviolet irradiation. It is important to take into account that some forms of leukoderma react to UV by increasing the degree of depigmentation, so such techniques should be prescribed with caution.
Prognosis and prevention
The prognosis of leukoderma regarding the patient’s life is always favorable – this dermatological condition never poses a threat of death or severe complications, only concomitant malformations in congenital forms and syndromes are capable of this. Regarding the recovery and restoration of normal pigmentation of the skin, the prognosis is often uncertain even in the case of relatively mild toxigenic forms of the disease. Congenital and immune varieties of leukoderma, as well as vitiligo, are extremely difficult to treat. Prevention includes the use of tyrosine-rich foods, protecting the skin from ultraviolet radiation and avoiding contact with chemicals that can cause depigmentation.