Lichen planus (lichen ruber planus) is a chronically occurring dermatosis, the characteristic and only element of which is the papule. The disease can be with lesions of the skin, mucous membranes and nails. The variety of appearance of papules, their localization and grouping causes a large number of clinical forms of lichen planus. For diagnosis in difficult cases, a biopsy is performed. Antihistamines, corticosteroids, antimalarial drugs, PUVA and phototherapy are used in the treatment.
Lichen planus occurs according to various data in 1.3-2.4% of cases of all dermatological diseases. And among diseases of the oral mucosa, its share, according to some authors, is 35%. Currently, there is an increase in the incidence. The disease occurs at different ages. Women suffer from lichen planus more often than men.
The exact mechanism and causes are still unknown. To date, disease is considered a multi-causal disease that occurs when exposed to various external and internal factors that lead to disturbances in immune and metabolic processes, as a result of which an inadequate tissue reaction develops in response to the provoking factor. There is a hereditary predisposition to the appearance of lichen planus.
Cases of the occurrence as a result of exposure to chemicals, including some medications (bismuth, tetracycline), are described. In these cases, the disease occurs as an allergic reaction to a chemical irritant. A toxic-allergic variant of development is often detected when an isolated red lichen planus occurs in the oral mucosa.
Cases of this disease with a nervous mechanism of development after stress, reflex segmental therapy and hypnosis sessions have been noted. Disorders of the gastrointestinal tract, pancreas, liver and endocrine system (for example, diabetes mellitus) play a certain role in the occurrence of the disease. Often the appearance of red lichen planus of the oral mucosa is associated with traumatic factors: poorly fitting dentures, sharp edges of teeth, lack of teeth, etc.
According to clinical manifestations , the following forms are distinguished:
- hypertrophic (warty);
- pemphigoid (bubbly);
- ring – shaped;
- erosive and ulcerative;
- rare forms.
Red lichen planus is characterized by a monomorphic rash consisting of flat papules (nodules) of red-purple or crimson-red color with a diameter of 2-5 mm. Papules have a retracted middle and a surface with a waxy sheen, clearly visible in side lighting. In most cases, there is only a slight peeling with hard-to-separate scales. In some cases, peeling may be similar to psoriatic (psoriasiform variant).
Rashes are more often multiple and arranged in groups, forming garlands, rings or lines on the skin. Papules can merge, while plaques are formed, around which new nodules appear. After the resolution of papules, persistent hyperpigmentation remains in the affected area. A rash of lichen planus is accompanied by itching, which can be expressed to a large extent, causing neurotic anxiety and sleep disorders in the patient.
Most often, disease affects the skin of the flexor surface of the extremities, the inner surface of the thighs, axillary and inguinal areas, the trunk and the mucous membrane of the oral cavity. With this pathology, nail changes can be observed: the appearance of longitudinal striation and scallops on them, clouding of the nail plate, destruction of the nail roller. Palms, soles, scalp and face are usually not affected by lichen planus.
In a quarter of patients with lichen planus, there is a lesion of the mucous membrane, not accompanied by rashes on the skin. Papules are located on the mucous membrane of the mouth, the vestibule of the vagina or the glans penis. They can be single or grouped in the form of lace, mesh, rings. The color of the papules on the oral mucosa is grayish-opal. Whitish flat plaques with jagged edges are formed on the tongue, and purple small plaques with a slightly flaky surface are formed on the lips.
The characteristic features include the Wickham grid symptom — the detection of a network-like pattern on the surface of the largest papules. It is well defined after lubricating the papules with sunflower oil. During the period of exacerbation of pathology, the phenomenon of Kebner is observed — the formation of new papules at the site of skin injury.
The hypertrophic (warty) form is characterized by warty layers caused by hyperkeratosis on the surface of brownish-red or purple plaques. Separate nodules are located around the plaques. A favorite localization of hypertrophic rash is the anterior surface of the shins. Sometimes there are separate foci of hyperkeratosis on the upper extremities and on the face. According to the clinical picture, they may be similar to basal cell carcinoma or senile keratosis.
The atrophic form develops in connection with sclerotic and atrophic changes at the site of rash resolution. Small foci of baldness may be observed on the scalp.
The pemphigoid (vesicular) form is manifested by the formation of vesicles (vesicles) with serous or serous-bloody contents. Vesicles can appear both on apparently healthy skin and on the surface of plaques and papules. Often, along with the bubbles, there are rashes typical of lichen planus. The usual localization of this form of the disease is the skin of the shins and feet. When large blisters occur, they talk about the bullous form of red lichen planus.
Moniliform is characterized by rounded waxy rashes grouped in the form of a necklace. The rash is located on the forehead, behind the auricles, on the neck, back of the hands, elbow bends, abdomen and buttocks. At the same time, the skin of the nose, cheeks, interscapular area, palms and soles remains intact.
The pigmented form, along with the characteristic elements of the rash, is accompanied by the appearance of pigment elements: brown spots and dark brown nodules. Sometimes they can precede typical lichen planus eruptions.
The pointed form is localized mainly on the skin of the neck, shoulder blades and lower extremities. Its elements are pointed papules. In the center of each papule there is a section of hyperkeratosis, protruding upward in the form of a horny spike.
The ring-shaped form is formed as a result of peripheral growth of the lesion with regression of elements in its center. Thus, the rashes form semicircles, rings and arcs. The ring-shaped form of red lichen planus is most often found in men on the skin of the inner surface of the legs and in the genital area.
Erosive-ulcerative form is observed on the mucous membranes, more often in the oral cavity. It is characterized by erosions and ulcers surrounded by an edematous and red area of the mucosa with typical eruptions of red lichen planus located on it. Erosions heal for a very long time, sometimes for years. After healing, recurrent erosions often occur in the same place or on a previously unchanged mucosa.
Rare forms of lichen planus include erythematous, obtotic and serpigious.
The presence of typical skin rashes allows a dermatologist to diagnose lichen planus according to the clinical picture. However, the variety of clinical manifestations and the existence of rare forms of lichen planus cause certain difficulties in its diagnosis in some cases. This mainly concerns the red lichen planus of the mucous membranes.
In patients with lichen planus, no specific changes are observed during laboratory tests. In some cases, a clinical blood test may include leukocytosis, eosinophilia and an increase in ESR.
In doubtful cases of lichen planus, a biopsy is necessary to confirm the diagnosis. Histological examination of the biopsy reveals inflammation, hyperkeratosis, hydropic dystrophy of the basal layer of the epidermis, hypergranulosis, stripe-like infiltration of the upper layer of the dermis, colloidal Sevatt corpuscles at the border of the dermis and epidermis.
The lack of a clear understanding of the causes and mechanisms of the development of lichen planus causes a variety of methods of its therapy. Treatment is carried out with the use of drugs that have a calming effect on the nervous system and relieve itching (chloropyramine, clemastine, cetirizine).
One of the methods of treating disease are PUVA therapy and selective phototherapy. Another technique is the combined use of corticosteroids (prednisone, betamethasone) and antimalarial drugs (chloroquine, hydroxychloroquine).
In most cases of lichen planus, local therapy is not carried out. The exception is the hypertrophic form, in which bandages with steroids, intra-focal diprospane injections, destruction of growths by laser or radio wave method are shown. When affected by red lichen planus of the mucous membranes, vegetable oils, corticosteroid ointments, phytoextracts, etc. are applied topically.