Leukoderma

LEUKODERMA, a skin lesion in the form of oval or round spots of various sizes, devoid of pigment. Hyperpigmentation is often observed at the periphery of the spots. L. belongs to dyschromias, which appear either as a result of preceding acquired skin diseases (in syphilis, so-called specific L., in psoriasis, parapsoriasis, seborrheic eczema, Gibert's roseola, pityriasis versicolor, tinea capitis, favus, leprosy, etc.) or can arise independently - spontaneous L. Often L. can be caused by external causes (chemical or physical agents) - artificial L. Meshchersky divides L. into leukoderma posteruptivum spontaneum, if it arises during the regression of the eruption without the aid of external factors, and leukoderma posteruptivum artificiale (pseudoleukoderma), if L. arose at the site of the regression of the eruptive elements under the influence of sunlight or other rays or drug treatment. Chrysarobin plays a significant role in the appearance of leukoderma posteruptivum artif.; an equally significant role must be attributed to the action of sun tanning during sun baths, causing so-called sun L. (Jadassohn, Feldman) in the presence of certain erythematosquamous dermatoses or even without visible preceding skin damage; in this case, the tanned areas have an increase in pigment, while the areas protected by crusts or scales do not give this tan. One can note the influence of the sun on the appearance of L. in syphilis on those areas of the skin where syphilitic eruptions had not previously been noted, for example, during prolonged exposure of the forearms to sunlight. This indicates that the exclusively specific nature of syphilitic L., which was questioned as early as 1893 by Kaposi, may still be considered not fully elucidated. Syphilitic L. (described by Neisser in 1883; pigmentary syphilid Pillon, 1853; Hardy, 1855) appears in the 3rd–6th month and later from the moment of infection and is considered one of the active manifestations of acquired syphilis; in children with congenital syphilis, L. is usually not encountered. Sometimes syphilitic L. arises at the sites of disappearing eruptions, but apparently it can also develop independently. Syphilitic L., observed more often in women than in men, sometimes has the appearance of a reticular pigmentation with wide gaps; in this case, the light depigmented spots are located close to each other - a reticular, net-like type, or lace form of L.; in other cases, there are very few spots, and they are located far from each other. In the spotted form of L., the white spots sharply stand out against hyperpigmented skin. One also distinguishes the so-called marble form of L., in which the contrast between hyperpigmented and depigmented areas is insignificant, which is why an impression of dirty marble skin is obtained. Initially located on the neck, especially on its lateral surface ("Venus' necklace"), L. sometimes spreads to the places adjacent to the neck - shoulders, chest, abdomen, etc. The duration of syphilitic L. is 5–12 months and longer. It responds poorly to specific treatment, but in the end passes on its own. Many authors note that in syphilitic L., pathological liquor is often detected (Ravaut, Bogdanov, Efron and Grzhebin).--The histological picture of syphilitic L. is characterized by the deposition of an infiltrate around the papillary and subpapillary vascular network, hyperplasia and swelling of the endothelium. Pigment is most often found only in the basal layer, and it is usually less than normal; only at the periphery of the spots, where there is hyperpigmentation of the skin, pigment is found slightly increased both in the epidermis and in the derma. - Among the various hypotheses of the origin of syphilitic L., there is an indication that it is a primary disorder of skin pigmentation, and the visible bleaching of leukodermic spots appears only as a contrast in relation to the developing hyperpigmentation of the skin. This disorder of skin pigmentation may also depend on damage to the vegetative nervous system. Some consider that syphilitic L. is the result of hyperpigmentation at the periphery of former roseolar or papular eruptions, while according to other authors, it is about depigmentation at the site of regression of elements of secondary syphilis, clearly or weakly expressed. In L. arising after the regression of elements of psoriasis, seborrhea, parapsoriasis, Gibert's roseola, the appearance of spots is associated with a local process, in particular with light and thermal rays, which cause, depending on their intensity, hyperpigmentation or depigmentation. In pityriasis versicolor subjected to the action of sunlight, the fungus could still be found in the depigmented spots, whereas on the tanned areas it was already absent. In leprous dyschromia (so-called morphee lepreuse), the characteristic features are complete anesthesia of the depigmented spots and the finding of leprous bacilli in histological sections. In cases of psoriatic pseudoleukoderma, the appearance of depigmented spots is caused not only by the desquamation of psoriatic papules. Such skin affected by psoriatic and seborrheic pseudoleukoderma is distinguished by decreased sensitivity to physical and chemical irritants, as well as decreased ability of the horny layer to absorb chrysarobin (Voronov). Closely related to L. in clinical picture are other skin depigmentations - naevus anaemicus (see Naevus) and leukoderma acquisita centrifugum, described by Suton and in its typical form having the appearance of round or oval depigmented spots with a small round, slightly raised brown spot (birthmark) in the center. In the etiology of all these skin dyschromias, damage to the vegetative nervous system and endocrine apparatus often lies (Suteev).

3. Grzhebin.