Carbohydrate dystrophies: causes, symptoms, diagnosis, treatment

Carbohydrate dystrophy can be parenchymal and mesenchymal. Carbohydrates, detected in cells and tissues, are identified by histochemical methods of investigation. They are divided into polysaccharides and glucoproteins.

Mucopolysaccharides can be neutral, strongly bound to proteins (chitin) and acidic (glycosaminoglycans). Which include hyaluronic acid, chondroitin sulfuric acid and heparin. Glucoprotsides differ from mucopolysaccharides in that the content of hexosamine in them does not exceed 4%. These include mucin and mucoids. Mucin is found in mucus, produced by the mucous membranes, mucoids are included in many tissues (heart valves, artery walls, ouggets, cartilage). Polysaccharides are detected in tissues by a SHIC reaction, in which a magenta color appears in the localization of polysaccharides. To identify glycogen, the control sections are treated with diastase or amylase, after which the red staining associated with the presence of glycogen disappears. Glycosaminoglycans and glucoproteins are determined in tissues when toluidine blue is stained as a reddish-lilac stain at the locations of glycosaminoglycans.

Degenerative degeneration due to impaired glycogen metabolism is observed in the skin with hereditary carbohydrate degeneration - glycogenoses, and in case of impaired glucoprotein metabolism it is manifested by mucosal dystrophy.

Mucous dystrophy - carbohydrate dystrophy, caused by a violation of the exchange of glucoproteins in cells, leads to the accumulation of mucins and mucoids in them. In this case, not only the increase in mucus formation, but also the changes in the physico-chemical properties of mucus occur. Many cells die and are desquamated, which leads to the formation of cysts. Examples of this kind of dystrophy in the skin can be follicular mucinosis and mucous mesenchymal dystrophy of the skin.

Mucous dystrophy can develop both in the epidermis and in the dermis. Dermal mucin normally forms the main substance of the connective tissue of the dermis and consists of glycosaminoglycans, especially hyaluronic acid. This type of mucin CHIC-negative, stained with alcian blue at a pH of 2.5 to 0.4 is metachromatic, hyaluronidazolabile. Epithelial mucin, called sialomucine, contains neutral mucopolysaccharides, often glycosaminoglycans. It is found in granules of dark mucoid secretory cells of the eccrine glands, slightly in the granules of the apocrine glands, in the cells of the cysts of the oral mucosa, in tumor cells in Paget's disease with perianal localization of lesions and adenocarcinoma of the digestive tract. Epithelial mucin CHIC-positive, hyaluronidazo and diastase-resistant, can be stained with alcian blue at a pH of 2.5 to 0.4, giving a weak metachromasia of toluidine blue.

Mucinosis of the skin is mesenchymal carbohydrate dystrophy, characterized by the release of chromotropic substances (glycosaminoglycans) from bonds with proteins and accumulating in the intercellular substance. At the same time, the collagen fibers of the connective tissue are replaced by a mucus-like mass (mucus), and its cells become process, become stellate.

Cutaneous mucinosis can be localized or diffuse, often associated with a dysfunction of the thyroid gland (hypo- and hyperthyroidism), although these changes can be observed even with its normal function. At the same time, mucin is found in the tissues, stained with hematoxylin and eosin in bluish color, with pronounced metachromatic properties when staining with toluidine blue and cresyl violet. On a general blue background, mucin looks reddish-violet. Mucicarmine stains it red.

With hypothyroidism, the cause of which is primary atrophy and inflammatory changes in the thyroid gland, the skin is pale, dry, waxy. Along with this, generalized or tuberous myxedema of the skin develops. When the generalized form develops continuous swelling of the skin, more often on the neck, neck, hands, legs and feet. Skin is inactive, poorly collected in folds, hair is dull and brittle, eyebrows may be missing, fragile, and burdens.

In tuberous myxedema, skin lesions, although widespread but less diffuse, manifest themselves as knotty seals, limited foci resembling plaques with a shagreen-like surface, resulting from the close arrangement of the elements. The general symptoms of hypothyroidism are less pronounced than in diffuse myxedemia.

Pathomorphology. The epidermis is mostly unchanged, except for the skin of the elbows and the area of the knee joints, where acanthosis can be observed. The dermis is considerably thickened, swelling of the collagen fibers is noted with the separation of their bluish masses of mucin, which are arranged in the form of a delicate net mainly around the vessels and in connective tissue capsules of the hair follicles. The content of glycosaminoglycans is increased by 6-16 times compared with the norm. At an electronic microscopy find out changes of fibroblastic elements in which collagen fibers are found.

In hyperthyroidism or thyrotoxicosis, in addition to the characteristic triad - the struma, tachycardia, exophthalmos - myasthenia gravis associated with the accumulation of glycosaminoglycans in the stroma of muscles, sometimes osteoarthropathies with subperiosteal ossifying periostitis of the distal ends of the phalanges, which look like drumsticks. On the skin of the face and trunk can be erythema, dermographism with urtikaropodobnoy reaction. Often there are hyperhidrosis, hyperpigmentation, trophic disorders (hair loss, nail dystrophy). Diseases of the sebaceous glands. A typical pretybial myxedema can be observed clinically characterized by the development of flat pillow-like seals of various sizes, the color of normal skin or yellowish-gray with a distinct pattern of hair follicles. Sometimes, with prolonged course, elephantiasis can develop. In the development of this form of mucinosis, in addition to thyroid dysfunction, other factors are likely to play a role, in particular, diencephalic disorders, hypersecretion of the thyroid-stimulating hormone, autoimmune reactions.

Pathomorphology. Massive hyperkeratosis with smoothing of epidermal outgrowths. In the dermis - large concentrations of mucin, especially in the middle sections, as a result of which it is thickened, collagen fibers are loosened. The number of fibroblasts is increased, some of them turn into mucous cells of stellate outlines, surrounded by munin. GW Korting (1967) called these cells mucoblasts. In them, electron microscopy finds a large number of organelles. In addition to these cells, a large number of tissue basophils are found. The capillaries of the upper third of the dermis are enlarged, their walls are thickened, around around there are small lymphocytic infiltrates.

Cutaneous mucinosis can occur with normal thyroid function. There are the following forms: scleromixedema of Arndt-Gottron, myxedema leuchen (papular micxedema), scleredemia of adults Buschke, follicular mucinosis, as well as reticular erythematous mucinous syndrome (REM syndrome).

Myxedema lychene (papular myxedema) is manifested by the precipitation of small glistening nodules of a hemispherical shape, densely located predominantly on the skin of the trunk, face and upper limbs. With the Arndt-Gottron scleromixememe, the eruptions are similar, but the tendency to merge with the formation of extensive foci, often sharply edematous, especially on the face and hands, is more pronounced. In the area of large joints are formed seals with the formation of coarse skin folds, on the face there may be nodularity and diffuse infiltration. With a prolonged course of the disease as a result of skin sclerosis, facial expressions are disrupted, movement of the upper limbs is hampered. There is a view that the scleromixedema of Arndt-Gottron is a variant of myxedematous lichen.

Pathomorphology. With myxedematous lichen in the skin, especially in the upper parts of the dermis, large fields of mucin are revealed, which when stained with hematoxylin and eosin look like basophilic masses. Collagen fibers in these places are loosened, thinned, pale, cell elements are scarce, star cells predominate. Vessels are dilated, the walls are swollen, mucin does not contain, sometimes around them there may be a small amount of lymphocytes and fibroblasts.

With the Arndt-Gottron scleromixode, there is a diffuse thickening of the dermis without intensive proliferation of fibroblasts. Mucin, as a rule, is revealed in the upper third of it. An increase in the number of connective tissue elements and tissue basophils was observed in electron microscopy. There is a close contact of numerous cells with collagen fibrils. L. Johnson et al. (1973) identified two types of fibroblasts: elongated and stellate. The first of them synthesize glycosaminoglycans, the second - collagen fibers.

Skleredema of adult Busca refers to a group of connective tissue diseases of unknown origin. Many point to the development of scleredema after acute infectious diseases, especially those caused by streptococcus. Sometimes scleredema is combined with diabetes, especially resistant to therapy, can be observed in children. It is manifested by swelling of the neck and face, which symmetrically extends downwards to the shoulders, trunk and arms. Brushes and lower body are usually not affected. In most cases, within a few months, the disease regresses, but in some patients the process acquires a protracted, long-term course, in rare cases, systemic changes in the muscle of the heart and other organs are possible.

Pathomorphology. The dermis is thickened 3 times in comparison with the norm. In all of its thickness, especially in the deep sections, there is edema, as a result of which collagen bundles become as if split, and elastic fibers - fragmented. The edema can be so strong that it leads to the formation of slits of various sizes (fenestration). The end parts of the sweat glands are located in the lower or middle parts of the dermis, and not at the border with the subcutaneous tissue, as in the norm. Subcutaneous fat is sometimes mixed with a dense connective tissue. In some areas of the dermis, an increase in the number of fibroblasts is found, among which there are many tissue basophils. In the early stages of the disease, histochemical reactions often reveal hyaluronic acid between bundles of collagen fibers, especially in areas of fenestration, which can be detected by staining with colloid iron, toluidine blue or alcian blue. In cases of prolonged course of the disease, hyaluronic acid in collagen beams may not be detected. Around the vessels there are focal infiltrates. Electron microscopy reveals an increase in the number of connective tissue cells with a large number of organelles, as well as an increase in the basic substance of the dermis, especially near elastic fibers. Collagen fibers sometimes form dense bundles or loosened, which resembles the early stages of scleroderma. Differentiate the disease from scleroderma, in which collagen fibers in the subcutaneous tissue, as a rule, are homogenized and hyalinized, weakly stained with eosin by the Masson method. In the sclerosis of adult Busca, the collagen bundles are unmodified and stained with hematoxylin and eosin as usual. In some cases, it is very difficult to draw a line between these two diseases.

[1], [2], [3], [4]