Focal scarring alopecia: causes, symptoms, diagnosis, treatment

Focal cicatricial alopecia with irreversible hair loss, or pseudopelade, is not a separate nosological form, but is the end result of the evolution of a number of atrophic dermatoses of the scalp (acquired or congenital).

Causes and pathogenesis of focal cicatricial alopecia. Focal cicatricial alopecia (FCA) can be caused by trauma (mechanical, thermal, chemical, radiation, including ionizing radiation). In these cases, the time and type of exposure can be easily determined from the anamnesis. Other causes include infectious skin diseases (pyoderma, dermatomycosis, viral dermatoses, tuberculosis of the skin, syphilis, leprosy, leishmaniasis), nevoid formations and skin neoplasms, developmental defects and genodermatoses, some acquired dermatoses. All of them gradually lead to atrophy and sclerosis of the skin and hair follicles on the head and end in persistent atrophic alopecia. Most often, focal cicatricial alopecia are caused by some acquired dermatoses localized on the scalp: red follicular decalvans lichen (more than 50% of cases), discoid lupus erythematosus, decalvans folliculitis (or lupoid sycosis), dermatomycosis, limited scleroderma. Much less often, focal cicatricial alopecia develops with skin sarcoidosis, lipoid necrobiosis, cutaneous lymphoma, Langerhans cell histiocytosis of the skin, cicatricial pemphigoid, as well as with some genodermatoses (scarring follicular keratoses, follicular dyskeratosis, congenital ichthyosis, congenital bullous dystrophic epidermolysis, etc.). Thus, the causes and mechanisms of development of focal cicatricial alopecia are varied and correspond to the etiology and pathogenesis of the dermatosis that ended in focal skin atrophy.

Symptoms of focal cicatricial alopecia. Atrophic dermatoses of the scalp occur 3 times more often in middle-aged women. Regardless of the dermatosis that caused focal cicatricial alopecia, the clinical picture is dominated by scalp atrophy of varying sizes with persistent hair loss. Foci of focal cicatricial alopecia, or pseudopelades, are usually located in the parietal and frontal areas, they are slightly sunken, and individual remaining hairs and tufts of hair are often visible within them. Cicatricial alopecia is noticed by chance, sometimes patients are bothered by a feeling of tension in the affected skin or slight itching. The dominant complaint is a cosmetic defect (especially in women), which leads to psychological trauma. The skin in the foci of atrophy is poorly yellow, smooth, shiny, stretched, thinned, devoid of hair and the mouths of hair follicles. When squeezed, it gathers between the fingers into small folds. In some cases, in addition to the predominant atrophic alopecia, it is not possible to detect primary or active secondary rashes. This is probably due to the "smoldering" course of pathological processes in the deep layers of the dermis and the prevalence of sclerotic and atrophic changes in the affected skin and hair follicles. It has long been noted that on the scalp, various dermatoses differ little in their clinical manifestations, often proceed atypically, with a small number of primary elements of the rash. Sometimes in the area bordering the baldness focus, weak hyperemia, peeling, horny "plugs" in the mouths of the hair follicles are found (with the follicular form of lichen planus, discoid lupus erythematosus, follicular keratosis, etc.). Folliculitis with follicular pustules in the border zone occurs with decalving folliculitis, infiltrative-suppurative form of mycosis, herpes zoster and other dermatoses. Sometimes in the lesions on the scalp it is possible to detect nodules, nodes, tubercles, etc. Various atrophic dermatitis of the scalp slowly progresses, the area of focal atrophy gradually increases, and after many years persistent baldness can become very pronounced (subtotal, total). In a combination of focal cicatricial baldness of the scalp with rashes in other localizations or with nail damage, it is also important to establish their origin, since in the overwhelming majority of cases these manifestations have a single genesis.

Pathomorphology of focal cicatricial alopecia. When examining the characteristic primary element of the rash at early stages of development, pathomorphological changes depend on the nosological form of the dermatosis that caused focal cicatricial alopecia. Taking into account the frequent atypical, "smoldering" course of atrophic dermatosis on the scalp, histological examination does not always help in diagnosing the dermatosis.

Diagnostics and differential diagnostics. When the dermatosis that caused focal cicatricial alopecia is localized only on the scalp (which is more common), determining the nosology of the disease becomes more complicated. First of all, focal cicatricial alopecia should be differentiated from circular alopecia, since their treatment and prognosis are quite different. With circular alopecia, there is no skin atrophy, the mouths of the hair follicles are preserved; in the marginal zone of the bald spot, there are hairs in the form of exclamation marks (a pathognomonic sign during hair traction). In the future, it is rational to first exclude diseases that most often lead to focal cicatricial alopecia: follicular decalving form of lichen planus, discoid and disseminated red valvula, decalving folliculitis, atrophic forms of dermatophytosis. The dermatologist should find out the anamnesis of the disease, carefully examine the entire patient, if necessary, conduct microscopic, microbiological, histological and immunological studies. During the examination, special attention is paid to the zone bordering the lesion where cicatricial alopecia has formed. There may be active manifestations of dermatosis (primary or informative secondary elements of the rash). It is necessary to establish the morphology of the primary element of the rash and its characteristics (color, size, shape, connection with the hair follicle, the presence of a horny spine in the center, possible changes in the hair, etc.). If rashes are detected in other localizations, their morphology and nosology are established, which practically predetermines the diagnosis of the original dermatosis on the scalp. In the absence of active manifestations of dermatosis on the scalp and in other localizations, dynamic observation of the patient is indicated.

Treatment of focal cicatricial alopecia. Rational treatment of the patient is possible only after establishing the nosology of the dermatosis that caused focal cicatricial alopecia. When prescribing drugs, the doctor should always weigh the real benefit and possible harm from treatment, since dermatoses that often cause focal cicatricial alopecia have a long-term chronic-recurrent course, requiring a course of treatment and dispensary observation of patients.

In case of noticeable foci of cicatricial alopecia, patients are recommended to appropriately model their hair, wear a hairpiece or wig, or use other methods of camouflage. When the dermatosis that caused focal cicatricial alopecia stabilizes, patients who are not satisfied with the proposed methods of camouflage and who have not reconciled themselves with a persistent cosmetic defect may undergo surgical correction of the bald spot (removal of the spot or autotransplantation of hair into the spot).

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