Lichen striatus is a dermatological disease of unclear etiology, in which papular rash is observed (the appearance of nodular elements on the skin). A symptom of this condition is rashes in the form of narrow stripes on the limbs and trunk. The rash distribution lines almost always correspond to the location of the nerve trunks. Diagnosis due to the specificity of the manifestations of this disease usually does not pose any special problems. Dermatological examination data are used, occasionally a skin biopsy is performed on the affected areas. Etiotropic treatment does not exist, supportive therapy is used, vitamins and corticosteroids are prescribed.
Lichen striatus is one of the rare varieties of dermatoses. The causes of the disease are still insufficiently studied. Pathology was first described in 1941 by dermatologists F. Sene and M. Caro. Lichen striatus usually affects children aged 2-3 years, occasionally occurs in adolescents and adults. According to medical statistics, the disease is more often diagnosed in girls than in boys. Manifestations of the disease occur suddenly and after a while spontaneously disappear even in the absence of treatment, for this reason, lichen striatus is considered a relatively easy-flowing dermatosis. The prognosis is favorable. All manifestations, including residual hypopigmentation, disappear within 3-4 years.
The etiology of this dermatological condition has not been reliably established, there are only assumptions about its nature. The most popular theory is about the relationship of skin manifestations and peripheral nerve damage. The hypothesis is partly confirmed by the location of nodules that line up in narrow bands corresponding to the projection of nerve trunks. This circumstance and the similarity of skin changes detected during histological examination allows some researchers to associate lichen striatus with a condition such as neurodermatitis.
According to another theory of the occurrence of lichen striatus, the disease is caused by congenital disorders of the development of nerve and skin tissues. As proof of the validity of this assumption, it is often indicated mainly the children’s age of patients. In addition, in some cases, the localization of rashes with lichen striatus does not correspond to the location of the nerves, but to the so-called Blashko lines. These lines are a consequence of the migration of embryonic skin cells and in a healthy person are usually indistinguishable to the naked eye. From the point of view of the second hypothesis, lichen striatus can be considered as skin manifestations of a mild form of embryopathy. However, to date, none of these theories of the development of the disease is proven and generally accepted.
As a rule, the symptoms of lichen striatus occur at the age of 2-3 years. The disease is characterized by a rapid onset, the transition from healthy skin to pronounced rashes can take only a few hours. The severity of the rash gradually increases, reaching a maximum within a few months. The leading manifestation of the disease is typical rashes, which most often occur on the skin of the hands, shins, buttocks and back, sometimes on the face. The distribution of the rash in lichen striatus is narrow strips up to 1-2 centimeters wide and 5 to 30 centimeters long. The lines can be straight, wavy or in the form of fancy curls. The lesion of the skin with lichen striatus is usually unilateral, the symmetrical location of the rash is practically not found.
When placed on the extremities, the rash bands always run parallel to the longitudinal axis of the arm or leg. At first they are more pronounced in the proximal part, then the nodules gradually appear distally. The rashes themselves with lichen striatus are usually represented by papular-squamous elements 2-3 millimeters in size, slightly protruding above the surface of the skin. Their color varies from slightly pink to bright red, the intensity of the coloring of the elements gradually decreases over time. Skin itching is rare, no other general or dermatological symptoms are detected with lichen striatus. At the beginning of the rash resolution, the papules begin to lighten, after their disappearance, areas of hypopigmentation remain. With a typical resolution of lichen striatus, pigmentation disorders of the skin also gradually disappear.
Despite the fact that most varieties of dermatoses are quite difficult to diagnose and differentiate, lichen striatus due to its specific symptoms is quite easily recognized during a routine examination by a dermatologist. On the patient’s skin, rashes are detected in the form of clearly marked stripes corresponding to the anatomical position of the nerves, or, less often, Blashko lines. Individual elements of the rash are represented by papular nodules 2-3 millimeters in size pink or red, with long-standing lesions, hypopigmentation of the skin may occur, indicating the beginning of spontaneous (or under the influence of treatment) resolution of symptoms of lichen striatus.
In controversial cases, a biopsy of the affected areas of the skin is performed with their further histological examination. With lichen striatus, lymphocytic and histiocytic infiltrates with a predominantly perivascular location are detected in the dermis. In the epidermis, a small number of lymphocytes and foci of acanthosis are detected, a violation of the processes of keratinization is possible. Histological examination is primarily necessary for the differential diagnosis of lichen striatus, which should be distinguished from the linear form of lichen planus, unilateral nevus and some forms of psoriasis. In rare cases, these conditions are so similar in their clinical manifestations that only the study of the tissue structure of lesions can clarify the diagnosis.
The position regarding the treatment of lichen striatus in dermatology is ambiguous. According to some experts, given the tendency of this condition to spontaneous resolution, no therapeutic measures are required. In some cases, the use of corticosteroid and naphthalene ointments is allowed to reduce such a symptom as skin itching. Other dermatologists claim that supportive treatment can stimulate the onset of resolution of skin rashes with lichen striatus and significantly accelerate recovery. The opinion of both groups of specialists has the right to exist, since this disease is almost always cured spontaneously sooner or later.
In the course of therapy of lichen striatus, corticosteroid, zinc and naphthyzine ointments are locally prescribed to reduce itching and the severity of inflammatory manifestations. Of the drugs of general action, vitamins are most often used, especially E and group B – according to some data, this accelerates the course of the disease almost twice. In the treatment of lichen striatus, physiotherapy measures are also widely used: ultraviolet irradiation, PUVA therapy and electrophoresis with vitamin remedies. It is assumed that visiting sea resorts and bathing also have a beneficial effect on the body in this condition.
Prognosis and prevention
The prognosis of lichen striatus is favorable, the average duration of the pathology in the absence of treatment is 2-3 years. For several more months (sometimes up to a year), residual phenomena remain on the surface of the skin in the form of linear hypopigmentation areas. Therapeutic measures have different effectiveness in different patients, but in some cases they can reduce the duration of the course of lichen striatus by half. Due to the ambiguity of the etiology and suddenness of development, preventive measures for this dermatological condition have not been developed.