Ectodermal dysplasia: causes, symptoms, diagnosis, treatment

Ectodermal dysplasia is a group of hereditary diseases caused by abnormal development of the ectoderm, and is combined with various changes in the epidermis and appendages of the skin.

The causes and pathogenesis of dysplasia of ectodermal disease have not been fully established. At present, several dozens of dermatoses of ectoderm origin are described in the literature. It is generally accepted that the following two forms are classical: anhydrographic and hydro-logical. The anhydratic form is often inherited by X-linked recessively, less often by autosomal recessive type. Family cases of the disease are described. The hydrodynamic form of ectodermal dysplasia is inherited autosomal dominantly. Some scientists believe that under the influence of X-rays, viral infections, chemical compounds, disulfide bonds in the L-keratin matrix fraction can occur.

Symptoms of dysplasia ectodermal. Both forms of ectodermal dysplasia develop shortly after birth or in early childhood with the formation of a complete clinical picture for the period of puberty.

Anhydrite ectodermal dysplasia (Crista-Siemens syndrome) is a heterogeneous disease, in most cases the heritable one is recessively linked to the X chromosome, the gene localization is Xql2-ql3. A complete clinical picture, including such basic signs as anhidrosis, hypotrichosis and hypodontia, is observed, with rare exceptions, only in men.

Anhydratic form of ectodermal dysplasia occurs mainly in males. Characteristic signs are the following triad: hypo- or anhidrosis, hypotrichosis, hypodontia. Initially, patients have a violation of thermoregulation due to hypo- or aplasia of the sweat glands. Patients with anhydrogenic form suffer from hyperthermia, which can be severe consequences for unrecognized cases. There is a decrease or absence of sweating throughout the skin, with the exception of the sites of localization of the apocrine glands, where it can more or less persist. Examination marked dryness and thinning of the skin. In some patients ichthyogeniform peeling, follicular hyperkeratosis, weakly noticeable keratodermia of the palms and soles. Due to dryness, conjunctivitis, laryngitis, pharyngitis, rhinitis, stomatitis develop. Eyelashes, eyebrows are rare, there is no hair in the pubic region and axillary basins. Pushkin hair is usually not affected. The appearance of the patients is typical: tired, old-fashioned face, low growth, large square skull with protruding frontal tubercles, massive chin, superciliary arches, high and broad cheekbones, sunken cheeks, bulging lips, large protruding ears (ears of satire), saddle nose , thinning hair down to alopecia. Teeth erupt late, long remain in the dairy stage, there is a large distance between the upper incisors, may not be in full or even completely absent, often deformed. Mental development in most patients is normal, sometimes signs of decreased intelligence, hearing loss, susceptibility to infections. In women, the disease proceeds in a relaxed form in the form of indistinctly pronounced dental abnormalities, focal sweating disorders, mild glandular development.

Hydraulic ectodermal dysplasia (Clawston syndrome) is inherited autosomally dominant, manifested by two main signs - hypotrichosis and abnormalities of the nails. It is assumed that the biochemical defect consists in decreasing the number of disulfide bonds in the fraction of a-keratin matrix.

With ectodermal hydrodysplasia, the main signs are nail dystrophy and hypotrichosis, to a lesser extent - palmar-plantar keratosis, pigmentation disorder. Sweating, as a rule, is not violated. Change of nails is the main, most frequent, and sometimes the only sign of the disease. Nail plates grow slowly, thickened, brittle, easily broken off, brown, deformed, sometimes atrophied. At the edge of the nails, as if corroded, split, longitudinally striated. There may come onycholysis.

Hair is thin, dry, easily break off, thinned, sometimes to the extent of total alopecia. Can be observed twisted hair, knotty brittle hair, their splitting, loss of eyebrows and eyelashes, sparse hair in armpits and pubic hair. There are foci of hypo- and depigmentation, reminiscent sometimes of vitiligo spots. There is a thickening of the terminal phalanges, a change in teeth is usually absent or insignificant. With age, the phenomenon of xeroderma is increasing.

Histopathology. With anhydrogic form of dysplasia, there are no sweat glands. Normal structure of the hair follicles and sebaceous glands. When hydroplastic dysplasia, hypoplasia of hair and sebaceous glands is observed.

Pathomorphology. In histological examination, thinning of the epidermis, hyperkeratosis with the formation of horny plugs in the mouths of the hair follicles, hypoplasia of the hair follicles and sebaceous glands are determined. With anhydrogic form, sweat glands are absent, while in hydrocotic form - within the limits of normal. However, the sweating symptoms that appear during the treatment with tigazone in patients with anhydrostic ectodermal dysplasia suggest that the number of sweat glands is only reduced and / or they are functionally inferior (their own observations). Hair changes in both types of ectodermal dysplasia are similar. They are twisted, changed by the type of knotty trichorexis. Often, hair rods smaller than normal diameter, marked asymmetry of hair follicles, proliferation of cells of their outer root vagina. Among the proliferating cells there are discretized; there is a new formation of hair follicles from the cells of the outer root vagina. The inner root vagina is thickened, deformed. Scanning electron microscopy revealed a decrease in the diameter of the hair shaft, a change in its shape from round to compacted; scales are cut atrophic or absent. Clamping of the cuticle cells is more noticeable towards the tip of the hair. The brain substance of the hair has a coarse-fibrous structure. Anomalies of keratinization may be due to a genetic change in the sequence of amino acids in proteins of the cortical and brain substances of the hair, which leads to a violation of the oxidation of thiol groups between the polypeptides of filaments of the cortex of the hair.

Differential diagnosis must be made with progerias, congenital syphilis, congenital pachyonichia.

Treatment of dysplasia ectodermal symptomatic. It is necessary to protect patients with anhydrogic form from overheating.

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