Pseudopelade, or atrophic focal alopecia

The term psevdopelada, or atrophic focal alopecia, is used to refer to a small-focal, slowly progressing cicatricial atrophy of the scalp with irreversible hair loss without pronounced perifollicular inflammation. In most cases, with the help of clinical, histological and other necessary research methods, it is possible to prove that cicatricial atrophy is the end result of the evolution of (sometimes very long) a number of known dermatoses localized on the scalp. First of all, these are atrophic forms of red lichen planus, discoid lupus erythematosus, limited scleroderma, decalving folliculitis, or lupoid sycosis. Much less often, focal atrophic alopecia can cause diseases such as follicular mucinosis, histiocytosis of the skin from Langerhans cells, lipoid necrobiosis, annular granuloma, sarcoidosis, metastases to the scalp of internal tumors, localized scarring pemphigoid, favus, etc. In these cases, atrophic alopecia is the final symptom of a number of skin diseases, and not an independent dermatosis. Therefore, R. Degos et al. (1954) proposed to name the final result of the evolution of a number of acquired dermatoses on the scalp with the condition of a pseudo-peloid, indicating the specific disease that caused it.

However, it is not always possible to determine the type of dermatosis that caused the development of atrophic focal alopecia. In these cases, it is considered possible to put, as a preliminary, the diagnosis of the "pseudo-Brocard". Further clinical and histological monitoring of such a patient (sometimes very long) can help to determine (including by exclusion) a specific dermatosis that led to focal atrophic alopecia. Significant diagnostic difficulties are due to the fact that the manifestations of a number of known dermatoses during their debut on the scalp do not differ much clinically, and their similarity is not only in the stage of pseudopelade formation (final stage) but also in the active stage of dermatosis and is manifested in the dominance of sclerotrophic processes in the affected skin.

Symptoms of pseudo-pancreas

In 1885 Brocq L. Described a pseudo-pellet (pelade - French - circular alopecia) as a separate nosological form, giving its clinical and evolutionary characteristics. Contemporaries unanimously adopted this concept and began to study the histological features of the pseudo-phelala. It is considered a rare disease (condition); occurs mainly in middle-aged women, sometimes in children. The debut of the disease often remains unnoticed due to the lack of subjective sensations. Unexpectedly for the patient, multiple small outbreaks of atrophic alopecia are found. In the initial period of the disease they are small, isolated, round or oval from 5 to 10 mm in size.

These foci can grow, merge into larger foci of irregular shape and always stand out sharply among the surrounding skin of the scalp. Usually, the number and size of foci are slowly increasing, but they can remain localized for a long time. By location and outlines, they were compared to the "archipelago of islands on a geographic map", "flame tongues", "thawed patches on the snow," "fingerprints of whites from finger flour," etc. Outbreaks of alopecia have different sizes, but with peripheral growth and fusion (very slow, for a number of years), they acquire semicircular, scalloped contours. The surface of the skin in the areas of alopecia is smooth, white, atrophic, without follicular skin pattern and peeling. At lateral illumination the smoothness of a surface and its shine is revealed. Atrophic areas somewhat sink, not compacted. Within their limits, individual hair beams of hair are often visible. Atrophic alopecia appears as if spontaneously, without preceding inflammatory manifestations, which distinguishes it from the formation of such alopecia in phavus.

On the periphery of the foci of the pseudo-pelvis there are no folliculitis, as happens with the decalting (epilating) folliculitis. Light reddening of the skin around the hair is rare, mainly in the initial stage of the disease and is short-lived. The hair that surrounds the visible foci of atrophy has a normal length and color. Sometimes in this area in the area of the outer openings of the hair follicles, the areas of the hair at the surface of the skin are colored darker and take the form of tattoo points in the follicle estuaries or the color of the licorice root (R. Diez, 1953). Patients usually do not detect fallen hair on the pillow or in the headgear. However, in the course of progressing, sipping of the hair in the marginal zone of the focus leads to easy removal of the hair. Roots of the removed hair are surrounded by juicy translucent whitish couplings. The course of the pseudo-pancreas is chronic, slowly progressing. After 15-20 years, hair can still remain, which can cover existing defects. In some cases of subacute flow, the distribution of atrophic baldness is much faster and can lead to almost complete cicatrical baldness 2-3 years later. Patients only occasionally complain about the feeling of tension of the affected skin, even less often - for a slight itch. Usually, complaints of a cosmetic defect predominate, which leads to psychological trauma.

Histopathology

In the early stages of pseudopelas, only a massive perifollicular and perivascular lymphocytic infiltrate with individual histiocytes is found, which is usually located around the upper and middle third of the follicle, without affecting its lower part; infiltrate penetrates into the walls of follicles and sebaceous glands, gradually destroying them. In the late stages of development (in old foci), the epidermis is atrophic, the epithelial outgrowths are smoothened. Changes in the dermis are characterized by fibrosis, loss of elastic fibers, necrosis of hair follicles and sebaceous glands. Bunches of collagen fibers extending vertically to the skin surface are allocated, and usually persistent sweat glands and muscles that lift hair.

The idea of a pseudo-peladion, as an autonomous disease, formulated by Brock gradually began to change. At first the notion of pseudo-pellet was expanded. It consistently included decalving folliculitis Kenko and spotty atrophy of the scalp, associated with follicular keratosis (prickly hair) (Rabut, 1953 and Prieto G., 1955). In 1955, Prieto Gay, discussing the origin of the pseudo-pellet, rightly argued that spotted atrophy due to damage to hair follicles on the scalp may cause red flat lichen, lupus erythematosus and scleroderma. So, as knowledge on clinical variants of some known dermatoses expanded, it became clear that the changes in the skin of the scalp caused by them differed little from the manifestations of the classical pseudo-phelala. Therefore, for pseudo-peluda as a terminal symptom common to a number of skin diseases, rather than independent dermatosis, it became impossible to give an accurate clinical and histological characterization (Degos R., 1953). To a large extent, they are determined by dermatosis, which caused focal atrophic alopecia, and is the stage of its development. Skin diseases that cause the condition of pseudo-pests, much more often affect other areas of the skin, and sometimes visible mucous membranes. Therefore, it is important to carefully examine the patient's entire skin, visible mucous membranes and nails. Any manifestations found outside the foci of atrophic alopecia on the head should be determined morphologically, histologically and nosologically. Clarification of the diagnosis will allow the doctor to properly orientate in the genesis of the pseudo-pancake and to prescribe adequate therapy. In those cases when using anamnesis, clinic and pathomorphology, it is not possible to establish a dermatosis, which caused focal atrophic alopecia. Diagnose the pseudo-brigade Broca as a disease of unexplained etiology. It should be borne in mind that the pseudomatosis causing dermatitis in a number of cases can be diagnosed only with prolonged clinical and histological monitoring of the patient.

Pseudopelas first of all need to differentiate from nasal baldness, as treatment and prognosis are different for them. With nest baldness, the mouth of the hair follicles is retained, there is no skin atrophy, therefore, hair growth is usually restored. In addition, in the marginal zone of the nidus (circular) alopecia are hair in the form of exclamation marks. They are shortened to 3 mm, the distal margin is roughened, split, and the proximal one is thinned downward and ends in a whitishly clavate thickened hair cone. This is a pathognomonic sign for nerpa baldness.

Rational treatment of patients with psevdopelade is difficult. It is advisable to have a detailed examination to identify hidden co-morbidities (chronic foci of infection, especially in the mouth, with nasal and ear nasal cavities, endocrine disorders, etc.). Recommended courses of antimalarial drugs, justifying this with a positive therapeutic effect in dermatoses, which often cause the condition of pseudo-pancreas (red flat lichen, discoid lupus erythematosus scleroderma, etc.). If the therapeutic effect of the general treatment is inadequate, or if it is impossible to carry it out, it is possible to apply intradermal injection into the marginal (active) zone of the focus of the crystalline suspension of triamcinolone (1 ml of Kenalog-40) diluted 3-5 times with a 2% solution of lidocaine. It is also possible to use an external cream (ointment) with a glucocorticosteroid.

When a noticeable pseudo-pelagus is formed, it is recommended to model hair, to wear a hairpiece or wig, or to perform a surgical correction (autotransplantation of hair into the atrophic focus or removal of skin areas with cicatrical alopecia).

State of pseudo-pancake

Many clinical observations have convincingly shown that when pseudopelade is formed, the manifestations of various dermatoses on the scalp - atrophic forms of red flat lichen, lupus erythematosus, scleroderma, decalvirating folliculitis (lupoid sycosis), etc., differ little. At the same time, the rashes of these dermatoses in other localizations retain their characteristic symptoms, so they differ from each other.

Difficulties in diagnosing diseases that cause a pseudo-pellet are caused by the appearance of a common property in various dermatoses on the skin of the scalp, which manifests itself in smoothing the symptoms characteristic of them and reducing clinical differences. Common and dominant in the clinical picture is focal scalp atrophy with hair loss. All this leads to "one-sidedness" of a number of diseases on the skin of the scalp, similarity of their clinical manifestations, not only in the stage of remission, but also in the active period.

When a pseudo-pellet is combined with rashes in other localizations, the doctor's orientation toward a single genesis of these manifestations is justified. The diagnosis of rashes on the skin of the trunk, limbs or visible mucous membranes predetermines the majority of the genesis of the existing pseudo-pelagus. In those cases, when the cause of atrophic alopecia is proved, ascertain the condition of the pseudo-peluda indicating the specific disease that caused it. For example, the condition of the pseudo-peloid caused by the follicular shape of the red flat lichen (or discoid lupus erythematosus, etc.). In these cases, atrophic cicatrical alopecia occurs again and is the final symptom of a number of skin diseases, and not an independent dermatosis. Early diagnosis of dermatosis allows the timely appointment of appropriate treatment, which stabilizes the disease and stops the progression of alopecia, but does not restore lost hair.

To establish the disease that caused the condition of the pseudo-pellet, it is important to clarify the history, a thorough examination of the whole patient, conduct microscopic, microbiological and histological studies, and in some cases - a long observation in the dynamics. When examining the scalp, special attention is paid to the area. Border with the focus of atrophic alopecia. Presence of hyperemia, flaking, altered hair (broken, with bases at the base, deformed, different color), yellow scales in the form of a scute around the base of individual hair, follicular pustules and inflammatory knots, purulent-bloody crusts, small scars in it and larger foci of atrophic alopecia, allow the doctor to suspect, and then eliminate fungal mycosis.

Pay attention to horny "corks" in the mouths of hair follicles on the skin, directly arriving at the focus of atrophic alopecia. Their formation is possible in the follicular form of lichen ruber follicularis decalvans, discoid lupus erythematosus, knee elastosis with cysts and comedones (blue actinic elastosis, or Favre-Rakusho disease), daryl follicular dyskeratosis, keratosis follicular prickly decalvation.

On the scalp can form inflammatory (nodules, pustules and nodes) and non-inflammatory elements. Thus, if folliculitis is found in the circumference of the focus of atrophic hair loss on the head, the presence and number of pustules, their connection with the hair follicles, the formation of erosive-ulcerative defects and purulent-bloody crusts should be determined. Folliculitis and pustules in this localization occur with decalcifying folliculitis and its clinical variant - lupoid sycosis of mycosis of the scalp. The formation of pustules on the scalp manifested chicken pox and shingles, necrotic acne, erosive pustular dermatosis of the scalp and eosinophilic pustular folliculitis. Inflammatory nodes on the scalp, followed by the formation of normal or atrophic scars with alopecia can be with the infiltrative-suppurative form of mycosis, the mycobacterial granuloma of Mayokki, which undermines both abscessed perifolliculitis and Hoffmann's follicular head.

Non-inflammatory nodules and nodes are formed in benign and malignant neoplasms of the skin and its appendages. In the lesions, the hair follicles are replaced by a newly formed tissue, sometimes they are destroyed by ulceration. Numerous large sebaceous hair follicles located in the skin of the scalp, predetermine, with other things being equal, a greater frequency of outgoing tumors. The baldness of the fronto-parietal region, which has early developed in men, leads to excessive exposure to sunlight and other unfavorable external factors on unprotected skin areas, which causes the development of dystrophic changes in it (dyschromia, telangiectasias, elastosis and atrophy) and predisposes to malignant neoplasms.

Teleangiectasias in the focus of atrophic alopecia can be formed in discoid lupus erythematosus, poikilodermic skin lymphoma, actinic keratosis, x-ray dermatitis and lipoid necrobiosis.

A significant value in the diagnosis of dermatosis, which caused the pseudo-peloid condition, has a histological examination of the affected skin. The correct choice of the biopsy site determines the success of this important study to clarify the diagnosis. The site of the skin should be selected in the border zone with the pseudo-peloid zone, where there are active clinical manifestations of dermatosis. A biopsy performed within the long-established atrophic alopecia or in the inactive stage of the disease. Useful information does not contain and therefore will not help in the diagnosis of dermatosis.

Further clinical manifestations, histopathology and differential diagnostics of dermatoses will be described, which often lead to the state of pseudo-phelps.

Dermatoses that lead to the condition of pseudo-pancreas

Atrophic forms of red lichen stripe

There are three atrophy clinical forms of red flat lichen, which with different frequency can lead to focal cicatricial atrophy of the skin, including on the scalp, i.e. To the state of the pseudo-pellet. These include follicular decalcifying lichen ruber (lichen ruber follicularis decalvans, synonyms: lichen ruber acuminatus, Hebra F.1862; Kaposi, M.1877; lichen planopilaris; Pringle JJ1895; lichen spinulosis and folliculitis decalvans, Little.G. 1930; lichen planus et. Atuminicans, Feldman, E.1922, 1936), atrophic lichen planus (lichen planus atrophicans, Hallopeau H. 1887), and pemphigus (pemphigoid) red lichen planus (lichen ruber planus bullosus / pemphigoides, vesiculosus).

Follicular decalcifying red lichen

With follicular decalcifying red lichen (FDC), the scalp is more often affected than other dermatoses. Some authors claim that in 90% of cases the pseudopelade is caused by red plaque (Prieto Gay, 1955; Kaminsky et al., 1967, etc.). Others (Silver et al., 1953), summarizing the literature data (101 cases) and 4 own observations, reduce the frequency of formation of atrophic alopecia on the scalp by half (42%).

Symptoms

Most often this clinical form of red flat lichen develops at the age of 30-70 years, although cases of an earlier onset are known. Most of the patients with lesions on the scalp are middle-aged women. Follicular decalving red lichen can begin with skin lesions of the scalp or trunk and limbs. On the head, the initial lesion occurs more often in the parietal region. These are usually small, about 1 cm in diameter, foci of mild hyperemia and flaking, irregular outlines with diffuse hair loss. It is hair loss that is usually the reason for contacting a doctor. Gradually, within the lesion sites, the skin becomes pale, smooth, shiny, stretched, the follicular pattern is smoothed out, hair completely falls out, - cicatricial atrophy develops. However, within the atrophied sites, separate hair is retained in places, sometimes - hair bundles. In the active stage of the disease at the edges of the foci there is a slight thinning of the hair of irregular contours and individual follicular scaly crusts that sometimes merge. Hair in the circumference of the focus of cicatricial atrophy is mostly preserved, but it is easy to epilate and on their root parts, glassy clutches 3 mm long are visible. Sometimes on the edge of the foci, you can find individual small cone-shaped follicular nodules and horny follicular "cork" The latter resemble "black spots" - low-cut hair with a chronic form of trichophytosis.

When comparing the described manifestations with the picture of the "classical" pseudo-pelas, it is not difficult to see their great similarity. The defeat of the scalp (pseudo-pelvis condition) can exist for a long time (from several months to 2-5-10 years or more) in isolation, slowly progressing and sometimes fading. In the long-term asymptomatic course of dermatosis, the formation of noticeable foci of skin atrophy on the scalp may occur many years after its debut. This significantly complicates the diagnosis of this rare form of red lichen planus. At the same time, when a pseudo-pellet is formed, the possibility of progression of the process without visible inflammatory phenomena (hyperemia and follicular papules) of the circle and within the focus of atrophic alopecia is clearly manifested. In this case, only an increase in its area in the parietal, occipital or temporal areas indicates a progression of dermatosis.

The amount of rashes on other parts of the skin is widely variable. Mostly on the extensor surface of the extremities and the trunk small, 1-2 mm in diameter follicular papules appear flesh-colored or pale pink with small horny spinules on the apex. They are usually located in isolation, only in some areas merging into small plaques. Sometimes follicular (perifollikulyarno) located papules have a rich red, stagnant color. The pointed horny corks in the center of the papules can be of different sizes, but usually do not exceed 1-1.5 mm in diameter. They have a dark brown or black color and resemble the appearance of comedones in seborrhea. Unlike comedones horny spinules are dense, stand above the level of the skin and when stroking the surface they give the impression of grating (a characteristic characteristic of "spinous lichen" - lichen spinulosus). With a certain effort, the hyperkeratotic spine (cone, cork) can be removed with tweezers, while exposing the widened and deepened mouth of the hair follicle. After the solution of the follicular papules, in a number of cases there remain scleroatrophic changes, which manifest themselves in different degrees in different parts of the skin. So, clearly visible atrophic alopecia (state of psedopelada) is always formed on the scalp of the head. In other parts of the body, hair also falls out, but distinct scar changes are not usually clinically visible. This applies primarily to hair loss in the pubic region and in the axillary regions. As shown by histological studies, such changes are explained by the death of hair follicles without pronounced signs of atrophy of other skin structures and integumentary epithelium. Thus, in place of follicular papules in the axillary areas, pubic area and in other areas of the lesion, hair loss is caused by sclerotrophic changes, but clinically this baldness is perceived as non-scarred.

A part of patients with this dermatosis (about 10%) are also affected by nail plates (thinning, longitudinal striation, fragility of the peripheral margin, pterygium, sometimes - atrophy).

Thus, the clinical manifestations of follicular decalcifying red lichen can begin with the scalp and for a long time it is limited (pseudo-peloidal condition), or accompanied by rashes of follicular prickly papules on the skin of the trunk or extremities. At the same time on the skin or visible mucous membranes there may be typical papules of red flat lichen, but this is infrequent.

In the literature, the combination of atrophic alopecia of the scalp, alopecia in the axillary regions, pubic area and follicular spiny papules on the trunk and extremities has long been known as the Picardy-Lassower-Little syndrome. The characteristic clinical manifestations of this syndrome are the result of the evolution of follicular papules of a single dermatosis - the follicular form of a red flat lichen. Individual symptoms of this triad or incomplete combinations of them are more common in clinical practice than a combination of all three at the same time.

At present, dermatologists have formed almost unanimous opinion about the Picardie-Lassuère-Little syndrome, as a manifestation of abnormal red flat lichen (follicular form), which is diagnosed in patients at late stages of development of this dermatosis.

Histopathology of the follicular papule with horny cork on the smooth skin in the early stage: the epidermis is not changed, the hair follicle is enlarged and filled with a horny plug, the wedge-shaped hypergranial disease of the follicular funnel, vacuolar degeneration of the cells at the border of the epithelium of the follicle and dermis; The lymphocytic-histiocytic infiltrate is mainly perivascular and perifollicular. Under the epidermis in places, ribbon-like infiltrates from lymphoid cells-histiocytes, which erase the boundary between the epidermis and the dermis; cells infiltrate penetrate into the outer hair vagina in its root part. At a late stage of development: varying degrees of atrophy of the epidermis. Epithelial outgrowths are smoothed, in the dermis the number of lymphocytes and histiocytes, located perivascularly and perifolliculally, is reduced, with marked fibrous manifestations; there are periinfundibulachnaya fibroplasia and cracks between the thinned follicle and damage to the dermis, fibrous strands replacing the collapsing hair follicles, with sclerosis in the interflicular parts of the dermis absent.

Diagnostics of the pseudo-pellet

If it is found on the scalp of the foci of atrophic alopecia, it is necessary first of all to exclude dermatoses, which most often lead to the condition of the pseudo-pellet. Objective examination of the patient begins with an examination of the zone bordering on the pseudo-pellet. Then consistently examine the entire surface of the skin, hair, nails, visible mucous membranes. When a rash is detected, the morphology of the primary vesicular element and its characteristics (color, size, shape, surface condition, connection with the hair follicle and the presence of keratosis in the center, etc.) are clarified. It should take into account the predominant localization of the rashes and the formation of elements of the rash at the injury sites (positive isomorphic reaction). If necessary, a histological examination of the affected skin is performed. Diagnosis of dermatosis, manifested by eruptions on the smooth skin and scalp, allows the physician to reasonably orient and in the origin of atrophic alopecia on the scalp.

With isolated atrophic alopecia on the scalp, diagnostic capabilities are limited due to the scarcity and erosion of active clinical manifestations of dermatoses in this localization and the almost identical end result of their evolution - the condition of the pseudo-phelala. It is necessary to study the anamnesis, histological study of the active focus and long-term observation of the patient in the dynamics.

Differential diagnostics

Eruptions of peaked follicular (perifollicular) papules on the skin of the trunk and extremities in FDDF are differentiated with the similar manifestations of some acquired and congenital dermatoses: red odoriferous hair follicle, follicular keratosis (hair follicles), lichenoid (miliary) syphilidae, small-node sarcoidosis, lichenoid skin tuberculosis, lichenoid trichophytide, follicular psoriasis, follicular spike-like decalvifying keratosis of Siemens (Siemens syndrome) and some others inherited of dermatoses accompanied by follicular keratosis.

Follicular decalcifying red lichen (FDKL) differs from red disruptive hair deprivation Deverzhi (ROV), firstly, by the absence of superficial erythematous squamous psoriasis plaques, which form a closely-grouped follicular conical papules of a yellowish-red color under the RED; secondly, the absence on the rear surface of the fingers of the fingers of the follicular papules with dark large horn cones in the center; Thirdly, patients with FDCA lack keratosis of the palms and soles, as well as erythematous-squamous, confluent facial lesions and a tendency to erythroderma. In FDDF, in addition to follicular papules, typical of the red flat discard papules on the skin and the visible mucosa, as well as pseudo-peloid and hair loss in the axillary regions and pubic region, can be simultaneously found.

From follicular keratosis (hair follicles) FDKL differs follicular prickly papules that have a perifollicular infiltrate, are grouped and can be accompanied by itching. For FDCA is not characterized by a predominant lesion of the buttock skin and the extensor surface of the shoulders, as well as a combination with acrocyanosis, xerosis and atopy. In addition to follicular papules, typical for red flat lichen papules on the skin (flat, polygonal, shiny, pinkish-violet with an umbilical impression in the center and a characteristic whitish-grayish network, standing out on the surface) and visible mucous membranes can form in addition to follicular papules. Part of the patients with FDKL also develops a pseudo-peloid condition, hair loss in the armpit and pubic areas. FDCA usually develops in adulthood, and not in childhood, has a characteristic evolution and recurs, but does not exist monotonously, for a long time without significant dynamics.

From the miliary syphilide, or syphilitic lichen, which manifests itself as follicular nodules of a rich reddish-brown color, the CHDKL differs in the solid or pale-red color of follicular prickly papules, usually symmetrically (and not distinctly grouped) and sometimes accompanied by itching. With FDKL, there is no jerking of the rashes and other manifestations of secondary syphilis (lenticular papules in the characteristic areas on the skin, mucous membranes of the mouth and genitals, polyadenitis, leukoderma, non-scarlet hair loss on the scalp), always negative serological reactions to syphilis

In contrast to the rarely lichenoid skin tuberculosis, depriving scrofulous tuberculosis, FDKL usually occurs in adults (rather than in childhood or adolescence), is not accompanied by skin manifestations on organ tuberculosis, exists longer (more than 2-3 weeks), may be accompanied by itching. In FDDF spiny follicular papules are usually not grouped on the lateral surfaces of the trunk and do not merge into coin-like plaques of a yellowish brown color, slightly flaky and slightly infiltrated, as in seborrheic dermatitis. According to FDCA, it is also possible the existence of typical for red flat lichen papules on the skin and visible mucous membrane, pseudo-peloid, hair loss in the axillary areas and pubic area, lesions of the nail plate. The results of the histological examination of the affected skin, which differ significantly, are of decisive importance. With follicular decalving red lichen, perifollicular and perivascular infiltrates do not have a tuberculoid structure.

From the small-skeletal form of the sarcoidosis of the skin, FDCA is characterized by pointed follicular papules with pegal spinules in the center (with this form of sarcoidosis, the papules are hemispherical, smooth with a slight central impression), the absence of the phenomenon of "dustiness" with diascopy (it is revealed in sarcoidosis the smallest yellowish-brown specks of dust , reminiscent of the symptom of "apple jelly" with lupous skin tuberculosis), the lack of a pronounced grouping, the rarity of localization on the face and the itching that can accompany the rash. Consideration should also be given to the papules on the skin and mucous membrane of the mouth that are typical for red squamous papules in a number of cases (in sarcoidosis, the damage to the oral mucosa is rarely possible psevdopelada, hair loss in the armpit and pubic areas, nail changes and the absence of systemic lesions characteristic of the sarcoidosis (mediastinal lymph nodes, lungs, liver, organ of vision, bones, etc.) The histological picture of these dermatoses is different: in sarcoidosis in the dermis, it reveals a typical epithelioid cell the exact granule.

The manifestations of FDKL on the skin of the trunk and extremities are morphologically similar to the lichenoid trichophytide. Distinguish them is not difficult, since the latter arises with active irrational treatment of patients with infiltrative-suppurative, rarely - superficial form of trichophytosis. Eruptions on the skin do not occur in the form of a rapid flare, they are not accompanied by general phenomena (fever, chills, malaise, leukocytosis) and do not disappear without leaving a trace in 1-2 weeks, which is typical for secondary infectious-allergic rashes in trichophytosis - trichophytids.

From the rare follicular form of psoriasis, FDCA is characterized by several other characteristics of the follicular papule. So, with FDKL deep in the center of the papule lies a comedopharyngeal spine, which can not be removed when scraping, there is also perifollicular infiltration. When the psoriatic follicular papule is scraped from its surface, a silvery white scales easily leave with a small superficial spine on the reverse side, and perifollicular infiltration is not detected. In a number of cases, the simultaneous presence in psoriasis-typical areas of flaky lenticular papules and plaques allows reproducing the symptoms of the psoriatic triad. It is also necessary to take into account the typical for red flat lichen papules on the skin and mucous membrane of the mouth, in some cases, the possible existence of a pseudo-peloid, hair loss in the armpits and pubic region, characteristic nail damage. It should be borne in mind that a very rare follicular psoriasis develops mainly in children after angina or another streptococcal infection and is localized mainly on the trunk. The histopathological changes that form follicular papules with these dermatoses also differ.

Follicular papules with FDKL, unlike similar elements of follicular dyskeratosis (PD), Darje, have a pointed form, pale pink or red, do not erode and do not vegetate, are not grouped and do not merge into plaques on seborrheic areas and in large folds of the skin, affect the extensor surfaces of the limbs, trunk and scalp. With FDCA on the scalp often develops atrophic alopecia, hair falls in the armpits and pubes, which does not happen with FD. It should also be borne in mind that PD usually begins before puberty (and FDCA usually after), has a prolonged recurrent course, can be accompanied by a disturbance of the psyche, hypogonadism, increased sensitivity to UV rays and a tendency to join in the lesions of pyococcal and viral infections. Pathomorphological changes in these dermatoses also differ substantially. For FD very characteristic of dyskeratosis. Follicular hyperkeratosis and subbasal acantholysis, leading to the appearance of suprabasal lacunae with uneven proliferation of dermal papillae in them.

Manifestations of FDKL and follicular mucinosis (FM) differ significantly, despite the partial similarity of localizations (the hairy part of the head, limbs). So, follicular papules in FM do not have such pronounced follicular keratosis as nodules in FDDF, they are bored and merge into small oval erythematous-squamous plaques with an underlined follicular pattern and weak infiltration. Hair within these plaques fall out, but skin atrophy does not occur, it is not typical for FDCA. It should also be taken into account that the course of FM is long, progressive. At the same time, atrophic alopecia of the scalp, hair loss in the armpits and pubic area, nail and mucous membrane damage do not develop. The picture of these dermatoses is different and histologically. FM is characterized by reticular dystrophy of the epithelial cells of the hair follicle and sebaceous glands with the formation of cystic cavities filled with mucin staining metachromatically toluidine blue, and perifollicular inflammatory infiltration.

The manifestations of FDKL must be distinguished from the follicular prickly decalcifying keratosis (FHDC) of Siemens. Both diseases are manifested follicular pointed decalpable papules with central horny spines, focal atrophic alopecia of the scalp and similar atrophic changes in the nail plates. However, FDKL is an acquired disease and usually develops in adulthood, more often in women, and FSDK is an inherited disease that appears soon after birth only in males. In FDDF, in addition to follicular prickly papules, a small perifollicular infiltrate on the extensor surfaces of the forearms, trunk and visible mucous membranes can also be typical papules of red flat lichen. In addition, part of patients with FDKL have hair loss in the armpit and pubic areas. In FSDK, miliary spiky papules with spinules affect from childhood mainly the scalp, the face, much less the extensor surfaces of the limbs. At the lesions of the scalp and eyebrows, focal atrophic alopecia develops, and atrophodermia appears on the face. In addition to FSDK, unlike FDCA, early damage to the organ of vision is characteristic (ectropion, conjunctivitis, keratitis, focal keratosis of the palms and soles is possible, sometimes there is a delay in physical and mental development.) The histopathological changes of the affected skin with these dermatoses also differ. Siemens lacks the perifollicular and perivascular lymphocytic-histiocytic infiltrates characteristic of the follicular decalcifying red lichen perifollicular in the dermis, as well as the vacuolar degeneration of the cells at the border of the epithelium hair follicle and dermis.

In childhood, the manifestations of a rare inherited disease - spindle-shaped hair aplasia, or mononiotrix, and superficial mycosis of the scalp are very similar. Clinical signs of spindle-shaped hair aplasia usually appear in early childhood in the form of broken hair (up to 1-2 cm) and horny follicular papules. Due to structural disorders and nodular deformation of the hair shafts, they break off (a symptom of black dots), at first in the occipital region, and then on the entire scalp. In addition, hair grows poorly, falls out, devoid of shine, twisted, with splittings at the end. This leads to diffuse, less often - focal hair loss. At the same time, the skin of the scalp also changes: small, densely arranged, skin color follicular horny papules appear (the surface is very much like goose-skin) and diffuse small-plate scaling. Often accompanying follicular keratosis of different severity on the extensor surface of the upper limbs and the posterior surface of the neck. With prolonged course, skin atrophy of the scalp with hair loss is possible. In these rare cases, a pseudofolus is identified and differentiated with other dermatoses that can cause it. From the questioning of the parents of such children it turns out that the defeat of the scalp began in early childhood and has a hereditary character. The clinical picture (hypotrichosis, follicular keratosis), anamnesis and microscopic examination of the hair (areas of its thickening of dark color alternate with thinned light fragments, reminiscent of the necklace, there are no fungus elements in the hair) allow to establish the diagnosis. Histologically, the skin shows follicular keratosis and an inflammatory infiltrate in the area of the hair follicles.

A preliminary diagnosis of FCDF should be confirmed by appropriate histological examination results.

[1], [2], [3], [4], [5], [6]