Parenchymal dystrophies

Depending on the type of substances whose metabolism is impaired, three groups of parenchymal dystrophies are distinguished:

1. Parenchymal dysproteinoses (protein metabolism disorders)
2. Parenchymal lipodystrophies (lipid metabolism disorders)
3. Parenchymal carbohydrate dystrophy .

The concept of parenchymal dysproteinosis combines:

• granular dystrophy ,
• hydropic dystrophy ,
• hyaline droplet dystrophy
• horny dystrophy ,
• aminoacidopathies (disturbances in the metabolism of amino acids).

Lipodystrophy in pathological anatomy is often referred to as lipidosis . Among parenchymal lipodystrophies, hereditary and acquired options are distinguished:

I. Hereditary parenchymal lipodystrophies (mainly sphingolipidoses ).

II. Acquired Parenchymal Lipodystrophy

1. Fatty liver ( liver steatosis , fatty hepatosis )
2. Myocardial fatty degeneration
3. Fatty degeneration of the kidneys .

Fat Histochemistry

For the diagnosis of lipodystrophy, a histochemical method for detecting lipids in a tissue section is often used. The principle of the technique is based on the ability of certain dyes to concentrate in fats. The following reagents are most commonly used:

• Sudan (III, black) - color fats in orange (Sudan III) or black (Sudan black B)
• Scarlet red ( scarlet-mouth ) - stains lipids in red
• Oil red O - also stains fatty substances red
• Osmic acid ( osmium tetroxide ) - dissolves in lipids, giving them a black color, but due to its high toxicity, is not used in the normal work of a pathologist, it is used for staining ultrathin sections designed for electron microscopy
• Nile blue - the express method of differential staining of lipids (acylglycerols are colored red, cholesterol and cholesterides are lilac, phospholipids are blue, free fatty acids and their salts are dark blue); the dye is unstable, so the study is carried out as the drug is ready, after a few hours the red tones disappear.

Sphingolipidoses

Sphingolipidoses - metabolic disorders of sphingolipids. There are three classes of sphingolipids ( sphingomyelins, gangliosides , cerebrosides ) and, accordingly, three groups of sphingolipidoses - sphingomyelins , gangliosidoses and cerebrosidoses . A variant of cerebrosides are sulfatides. Sphingolipidoses belong to thesaurismosis ( accumulation diseases ) - hereditary diseases in which an accumulation of a substance occurs due to the absence or defect of the enzyme that metabolizes it.

I. Sphingomyelinosis ( Nimann-Peak disease ).

II. Gangliosidoses

1. Thei-Sachs disease
2. Sandhoff — Norman — Landing Disease
3. Juvenile gangliosidosis .

III. Cerebrosides

1. Glucocerebrosidosis ( Gaucher disease )
2. Galactocerebrosidosis ( Krabbe disease )
3. Fabry disease - a violation of the metabolism of di- and trihexosocerebrosides
4. Sulfatidosis ( Greenfield-Scholz disease )
5. Austin's disease is a combined violation of the metabolism of sulfatides and mucopolysaccharides.

The leading changes characteristic of this group of diseases are damage:

• nervous system
• liver
• spleen .

Sphingomyelinosis

Sphingomyelinosis ( Nimann-Peak disease ) is caused by a violation of the activity of sphingomyelinase , which breaks down sphingomyelins . These substances accumulate in the neurons of the brain and macrophages of the internal organs, determining the development of cerebral and visceral syndromes. In the vast majority of cases of sphingomyelinosis (85% of cases), there is an acute infantile neurovisceral type of disease, especially characteristic of Jewish families. As a rule, the disease manifests itself during the first half of the child’s life, but congenital cases are also known. An important diagnostic sign is a cherry-red spot on the fundus (found in half of patients). Children usually die in the second year of life.

Against the background of general depletion and dehydration, the skin acquires a brownish-yellow tint, primarily in open areas of the body. The spleen is significantly enlarged, dense, brick-red in color, mottled in the section due to the alternation of brick-red and yellowish areas. The liver is also significantly enlarged, compacted, from ocher-yellow to brownish-yellow in color, in the section its tissue has a clay look. Lymph nodes are enlarged, in the context of the color of the egg yolk. The adrenal glands are enlarged, lighter than normal. In the lungs there are small foci resembling miliary tubercles, or mesh yellowish infiltration. The kidneys are moderately enlarged, the cortical substance is light gray. The brain may not be changed externally, in some cases atrophy due to gray matter and areas of demyelination are detected.

During micromorphological research in the brain tissue and in various internal organs, especially in the liver and spleen, Pika cells are detected - cells whose cytoplasm contains numerous lipid inclusions and therefore takes the form of a “soap foam” ( foam cells ). Peak cells are primarily neurons and macrophages , but some epithelial cells are also able to accumulate sphingomyelins. The largest number of Peak cells is noted in the liver, and the most severe changes are detected in the brain: neurons are sharply enlarged, resemble cells in a state of balloon dystrophy . On electron diffraction patterns, lipid inclusions in the cytoplasm look like vacuoles with myelin-like bodies (biomembranes rolled up).

Gangliosidoses

Gangliosidoses develop as a result of a violation of the activity of lysosomal enzymes hexosaminidases that break down gangliosides. Hexosaminidase A - an enzyme of neurons, hexosaminidase B - macrophages and some other cells. Gangliosidoses include Tay-Sachs disease, Sandhoff-Norman-Landing disease, and juvenile gangliosidosis. For gangliosidoses, amavrotic idiocy syndrome is characteristic ( amavrosis is complete blindness, idiocy is a severe form of oligophrenia). In addition to gangliosidoses, amavrotic idiocy develops with primary neuronal lipofuscinosis .

1. Tay-Sachs disease ( infantile amavrotic idiocy ) is characterized by a complete absence of hexosaminidase A activity (in this case, gangliosides accumulate in neurons). Clinical manifestations mainly develop by 6 months. of life. Death occurs, as a rule, at the age of 2-5 years with complete blindness, immobility and severe exhaustion. The brain is first enlarged, then decreases. White substance of rubber density. The border between white and gray matter has been erased. All neurons of the brain and retinal ganglion cells are sharply increased due to the accumulation of gangliosides (cytoplasm and processes are swollen, the nucleus is pushed to the periphery). Neurons gradually die, in their place neuroglia ( gliosis ) grows. For intravital diagnosis of the disease, a rectal biopsy is performed. In the retina at the site of the yellow spot, red is detected.

2. Sandhoff -Norman-Landing disease — unlike Tay-Sachs disease, gangliosides accumulate not only in neurons, but also in macrophages of internal organs and in the cells of the renal tubules. The disease is based on the complete lack of activity of hexosaminidases A and B.

3. Juvenile gangliosidosis - the disease is characterized by a partial defect in hexosaminidase A. The morphological picture is similar to Tay-Sachs disease, but develops at the age of 2-6 years. Patients usually die at the age of 6-15 years.

Cerebrosidosis

Cerebrosides include Gaucher , Crabbe , Fabry and Greenfield-Scholz disease . This group often includes Austin's disease - a combination of Greenfield-Scholz disease and mucopolysaccharidosis .

1. Gaucher disease ( glucocerebrosidosis ). [ Philip Gaucher - French dermatologist.] In Gaucher disease, glucocerebroside accumulates in the tissues. There are three types of Gaucher disease:

• infantile
• juvenile
• an adult .

The infantile type manifests itself in the first year of life. After 1-2 years, the children die. The main changes are detected in the brain in the form of progressive death of neurons. Cerebrosides accumulate in the cytoplasm of macrophages, which are called Gaucher cells . The liver and spleen are sharply enlarged. Gaucher cells are also found in the brain.

The juvenile type manifests after a year of life. Gaucher cells are absent in the brain. Typical skeletal changes are thoracic kyphoscoliosis, bulbous femurs, sphenoid or flat vertebral bodies. Death occurs at the age of 5-15 years.

The adult type of the disease manifests itself in childhood and progresses very slowly. As a rule, patients live up to 20-25 years. The most pronounced changes are found in the spleen. In addition to splenomegaly, hypersplenism is noted - increased destruction in the red pulp of the spleen of blood cells. Hypersplenism causes the development of anemia, leukopenia (against which infectious complications arise up to sepsis) and thrombocytopenia. Sometimes panmyeloftis (emptying of the red bone marrow) is formed.

2. Galactocerebrosidosis ( globoid cell leukodystrophy Krabbe ). [ Knud Haraldsen Krabbe ( 1885 - 1961 ) - Danish neuropathologist.] The disease is based on a deficiency of the enzyme β-galactosidase , which cleaves galactose from the cerebroside molecule. Usually immediately after birth or in the first 6 months. of life, brain damage is manifested. Characterized by rapidly increasing muscle stiffness, especially the muscles of the lower extremities, general motor anxiety (extrapyramidal hyperkinesis). Various stimuli cause attacks of tonic convulsions, often occurring with loss of consciousness. Atrophy of the optic nerve leads to impaired vision. In the terminal stage of the disease, a picture of decerebral rigidity develops (damage to the midbrain caudal to the red nuclei, manifested by a sharp predominance of extensor muscle tone): a tilted head and straightened limbs. Children die from intercurrent diseases or due to bulbar paralysis. Life expectancy is one year. Intravital morphological diagnosis is possible on the basis of a peripheral nerve biopsy. Macromorphological examination reveals atrophy of the brain and spinal cord, expansion of the cerebral ventricles. Foci of compaction are diffusely located in white matter, and jelly-like foci of softening in gray. Galactocerebrosides accumulate in gliocytes and in adventitia of vessels of the brain and spinal cord, in hepatocytes and epithelium of the renal tubules. In the substance of the brain around the small veins in the form of couplings, giant multinuclear cells are located, similar to Langans cells , with a peripheral arrangement of nuclei near the inner surface of the cytolemma. They are specific for Crabbe disease and are called globoid cells . Globoid cells together with lymphoid cells form perivascular granulomas . Typical lymphocytic granulomas without globoid cells are found.

3. Diffuse angiokeratoma of the trunk of Fabry. [ Johann Fabry ( 1860 - 1930 ) - German dermatologist.] The disease develops due to a defect in the lysosomal enzyme α-galactosidase , resulting in the accumulation of di- and trihexose-cerebrosides. Digexosis-cerebrosides accumulate mainly in the kidneys and pancreas; they are excreted in the urine. In other organs, mainly trihexosis-cerebrosides are deposited. Almost exclusively men are affected ( androtropism ). The disease begins at the age of 7-10 years. Death occurs, usually at the age of 40 years from renal or cardiovascular failure. The disease is generalized in nature with damage to various organs and tissues. Damage to the central and peripheral nervous system is clinically manifested by paresthesia, especially of the upper extremities, with rheumatic arthralgia, headaches and a decrease in intelligence. Visceropathy proceeds in the form of cardio - vasorenal syndrome . At the same time, renal failure with constant isostenuria and transient azotemia attacks develops, edema mainly on the lower extremities, expansion of the borders of the heart, arterial hypertension. Changes in the organ of vision are clouding of the cornea, tortuosity of the arteries and veins of the fundus. Small bluish, dark red or blackish nodules ( angiokeratomas ) appear on the skin and visible mucous membranes. The greatest number of angiokeratomas is determined on the skin of the anterior abdominal wall in the paraumbilical region, in the axillary cavities, on the scrotum, on the skin of the hips, cheeks and terminal phalanges of the fingers, on the mucous membrane of the oral cavity, the conjunctiva of the eye and the red border of the lips.

4. Greenfield — Scholz metachromatic leukodystrophy . This disease, like Fabry disease, refers to lysosomal diseases , since the disease is based on a deficiency of the lysosomal enzyme arylsulfatase A , which cleaves sulfate from a sulfatide molecule ( cerebroside sulfate ). Sulfatides are stained metachromatically with cresyl violet in brown. There are three forms of the disease:

• infantile
• juvenile
• adult .

The infantile form is most severe, clinical symptoms appear in 2-3 years of life (sleep disorder, gradual loss of speech, amaurosis and deafness, mental retardation , spastic paresis and paralysis , turning into decerebral rigidity). Death occurs within 1-3 years. For the purpose of intravital morphological diagnosis, a biopsy (rectal or peripheral nerve) is used. At the same time, metachromasia is detected in the cytoplasm of macrophages and lemmocytes. Macromorphological examination indicates atrophy of the brain, a densification of its substance. The accumulation of sulfatides occurs in gliocytes, primarily in oligodendroglia cells, to a lesser extent - in neurons. Electron diffraction patterns show enlarged lysosomes with layered structures.

Acquired Parenchymal Lipodystrophy

Acquired parenchymal lipodystrophies are associated with impaired metabolism of acylglycerols ( neutral fats ) in the parenchyma of organs and most often develop in the liver, myocardium, and kidneys.

Parenchymal Fatty Liver Dystrophy

Changes in the liver in this case are indicated by the terms steatosis or fatty hepatosis . The causes of fatty hepatosis are various pathological processes (infections, alcoholism, diabetes mellitus, chronic hypoxia, protein deficiency in food). Macromorphologically, the liver is enlarged, its tissue is flabby, the color depends on the severity of steatosis (light brown with moderate steatosis, yellow - with severe and whitish - with a pronounced process). The liver with whitish fatty hepatosis is called the “ goose ”, since in waterfowl this type of organ is common. Microscopic examination in the cytoplasm of hepatocytes revealed drops of acylglycerols, stained with the corresponding histochemical reagents. There are three degrees of severity of the process: (1) pulverized , (2) small-drop and (3) large- drop “obesity” of hepatocytes. A diagnosis of steatosis by liver biopsy is possible only with at least half of the changed parenchymal cells.

Parenchymal fatty degeneration of the myocardium

Acquired parenchymal myocardial lipodystrophy develops with decompensation of cardiac activity (in a "worn out" heart). An organ is typically called a tiger heart . It is enlarged due to the expansion of cavities, its walls are thinned compared to the compensated state, the myocardium is flabby, clayey yellow, small yellowish spots and stripes are visible from the endocardium (areas of the maximum concentration of acylglycerols in the cytoplasm of cardiomyocytes). However, yellow stripes are formed extremely rarely, more often there is a picture of small yellowish spots randomly scattered along the endocardium of the left ventricle. Microscopic examination revealed drops of neutral fat in the cytoplasm of cardiomyocytes. In the parenchymal elements of the heart there is (1) pulverized and (2) small-droplet “obesity”. Large droplets of fat in these cells usually do not form.

Parenchymal fatty degeneration of the kidneys

Acquired parenchymal lipodystrophy in the kidneys is noted with nephrotic syndrome , as is hyaline droplet degeneration of tubular nephrocytes. It occurs due to reabsorption of lipoprotein particles, which in this syndrome is rich in primary urine. If there are no gross changes in the kidney (for example, with amyloidosis or nephritis), the organ with signs of parenchymal lipodystrophy is slightly enlarged, its tissue is flabby, the cortical substance is expanded, yellowish-gray in color. Microscopic examination in the cytoplasm of tubular nephroepithelial cells, along with protein drops (intracellular hyalinosis), drops of neutral fat are detected. As in hepatocytes, there are:

• dusty
• small droplet and
• large-drop "obesity".

Parenchymal carbohydrate dystrophies are accompanied by metabolic disorders

• glycoproteins
• glycogen ( glycogenopathy ).

Many proteins of the body are glycoproteins. In pathological anatomy, mucous substances ( mucins ) and mucus-like substances ( mucoid , pseudomucins ) are of primary importance. The accumulation of mucins and mucoid is called mucosal dystrophy . As a variant of mucosal dystrophy, colloid dystrophy is considered - the accumulation of mucus-like substances in the tissue with their subsequent compaction in the form of a colloid.

I. Disorders of glycogen metabolism (glycogenopathy)

1. Hereditary forms ( glycogenosis )
2. Acquired forms [for example, in diabetes mellitus].

II. Mucous dystrophy

1. Inherited forms [eg, cystic fibrosis]
2. Acquired forms .

Among thesaurismoses, a group of glycoproteinoses is distinguished, which includes diseases such as sialidosis , fucosidosis , mannosidosis and aspartyl glucosaminuria .

Carbohydrate Histochemistry

Most often in pathological practice, three histochemical methods are used to detect carbohydrates: the PAS reaction, Best carmine staining, and metachromatic methods for determining free hyaluronic acid.

1. The total detection of glycogen and glycoproteins in the tissue section is usually carried out using the PAS reaction , which is often called the “ SIC reaction ” in the Russian literature (from the name of the reagent - Schiff-iodic acid ). The Schiff reagent contains the red dye main fuchsin , thanks to it glycogen and glycoproteins turn red. If necessary, the sections are treated with the amylase enzyme (diastase) in order to distinguish glycogen from glycoproteins ( PASD reaction ).

2. Glycogen can be detected by carmine staining according to the Best method . Glycogen granules are stained dark red.

3. To detect free hyaluronic acid in the tissue with mucoid edema, use the dye toluidine blue , which stains the areas with free hyaluronate in red (the ability of the fabric to stain in a color different from the color of the dye is called metachromasia ).

Glycogenosis

Glycogenoses are thesaurismoses in which there is no glycogenolysis due to the insufficiency of enzymes that break down glycogen. Moreover, the accumulation of glycogen occurs in the cells of a number of organs. The type of glycogenosis, in addition to eponym, is designated by the Roman numeral: type I glycogenosis — Girke’s disease , II — Pompe’s disease , III — Forbes-Cory disease , IV — Andersen’s disease , V — Macardle’s disease , VI — Era’s disease , VII — Thomson's disease , VIII - Tarui disease , IX - Hag disease , etc. The first six types of glycogenoses have been studied in most detail.

Classification

Glycogenoses are classified depending on the primary location of the lesion and the chemical characteristics of glycogen.

I. Predominant localization of the lesion

1. Hepatic glycogenosis (I, III, IV, VI)
2. Muscle Glycogenosis (V)
3. Generalized glycogenosis (II).

II. Chemical features of glycogen

1. Glycogenosis with unchanged glycogen (I, II, V, VI)
2. Glycogenosis with the presence of abnormal glycogen (III, IV).

Abnormal types of glycogen with glycogenosis:

• Limdextrin ( limitdextrinosis - type III)
• Amylopectin ( amylopectinosis - type IV).

Hepatic forms are characterized by enlarged liver. Muscle glycogenoses are usually accompanied by the development of skeletal muscle weakness due to the accumulation of glycogen ions in the sarcoplasm. With generalized glycogenosis , various organs suffer, but cardiac damage (cardiomegaly) and the development of chronic heart failure are of major importance.

In Forbes-Cori disease, glycogen has short side chains (normally long) and is called limitdextrin , and the disease is called limitdextrinosis . In Andersen's disease, glycogen does not form lateral branches and is a linear molecule, it is called amylopectin (by the unsuccessful analogy with starch amylopectin), and the disease is amylopectin . At the same time, amylopectin damages hepatocytes, on the site of necrosis of which fibrous tissue grows and liver cirrhosis forms in the first years of a child’s life.

Glycogen macroscopy

In pathological anatomy, a technique has been developed for the rapid diagnosis of glycogenosis (diagnosis "at the section table"). A macroscopic test for glycogen determines its presence in the organ only in large quantities, which is typical for glycogenoses. The usual amount of glycogen in this way cannot be detected. The reason for the conservation of glycogen in cells during glycogenosis is the absence of posthumous glycogenolysis.

The test is carried out in three stages:

• Stage 1 - the tissues are soaked in an aqueous solution of formalin (in this case, the liquid becomes cloudy, whitish, like diluted milk)
• Stage 2 - under the action of ethanol, gelatinous masses fall out of this solution
• Stage 3 - under the influence of iodine-containing reagents (for example, Lugol's solution), the precipitate acquires a saturated brown color.

Hepatic glycogenosis

Hepatic glycogenoses include Girke's disease (type I), Forbes-Cory disease (type III), Andersen's disease (type IV) and Era's disease (type VI). Type VI glycogenosis is divided into two options: Era-I disease and Era-II disease .

1. Girke's disease. [ Edgar Otto Konrad von Girke ( 1877-1945 ) is a German pathologist.] Girke's disease is based on glucose-6-phosphatase deficiency . The liver is primarily affected, it is sharply enlarged, the color of its tissue in the section is pink. The spleen is of normal size. The kidneys are enlarged due to the bark, acquiring a yellowish pink color. Since glycogen is “locked up” in hepatocytes, patients develop hypoglycemia, so patients often eat a lot, which leads to obesity ( alimentary hereditary obesity ). Fat is deposited primarily on the face. Small growth ( hepatic infantilism ) is characteristic. The intestines and heart may be affected. Leukocytes overloaded with glycogen (primarily neutrophilic granulocytes) are functionally inactive, as a result of which various infectious processes develop up to sepsis. Microscopic examination of liver tissue reveals sharply enlarged hepatocytes with light (optically empty) cytoplasm. Such hepatocytes resemble plant cells. The phenomenon of light cytoplasm in the presence of a large amount of glycogen in it is explained by leaching of this substance with aqueous solutions of various reagents. Nevertheless, the Best reaction is positive even after fixing the material in formalin.

2. Forbes disease — Cori ( limit dextrinosis ). [ Gilbert Burnett Forbes - American Pediatrician.] This disease produces glycogen with short side chains ( limitdextrin ). The liver is mainly affected in the form of moderate hepatomegaly. The disease proceeds favorably.

3. Andersen's disease ( amylopectinosis ). The disease was described by American Dorothy Ganzina Andersen . The cause of the disease is a defect in the branching enzyme , which provides the synthesis of glycogen side chains. In patients with amylopectinosis, glycogen molecules acquire a filiform shape without lateral branches. Such glycogen not only breaks down with difficulty, but also damages the cell, causing its death. Already at the end of the first - beginning of the second year of life, the child develops cirrhosis of the liver. Other manifestations of the disease (ascites, jaundice, bleeding, splenomegaly) are caused by cirrhosis. Children usually die in the first five years of life. Andersen's disease is often combined with cystic fibrosis.

4. Disease Era-I. [ HG Hers - French biochemist.] At the heart of the disease is a deficiency of hepatic phosphorylase , so the liver is mainly affected in the form of hepatomegaly. Characterized by small growth of patients and excessive accumulation of fat on the buttocks.

5. Era-II disease is a combined defect in muscle and hepatic phosphorylases . The disease is manifested by signs of Macardle and Era-I diseases: damage to the myocardium, skeletal muscle and hepatosplenomegaly.

Muscle Glycogenosis

The most common muscle glycogenosis is MacArdle disease (type V glycogenosis). [ B. Macardle - English pediatrician.] It is caused by a defect in muscle phosphorylase . The first symptoms appear at the age of 10-15 years (muscle pain during physical exertion). Muscle weakness gradually develops. With this type of glycogenosis, only skeletal muscle is affected. During physical activity, muscle fibers break down. Myoglobin released during this stains urine.

Generalized Glycogenosis

A typical generalized glycogenosis is Pompe disease (type II glycogenosis). [ J.K. Pompe - Dutch pathologist.] This disease occurs due to a deficiency of the lysosomal enzyme acid maltase , so glycogen accumulates in the lysosomes. The most pronounced damage to the muscles and nerve tissue. The course of the disease is very unfavorable - children die in the first year of life. Muscular organs are enlarged, especially the heart and tongue ( cardiomegaly and macroglossia ). Microscopic examination of the myocardium reveals enlarged cardiomyocytes with a light cytoplasm.

Acquired Glycogenopathies

Acquired forms of glycogen metabolism disorders are widespread and occur in various diseases. The most characteristic violation of glycogen metabolism in diabetes . The amount of glycogen in the tissues of the body with this disease, with the exception of the kidneys, decreases.

In hepatocytes, a peculiar compensatory process is noted - part of the glycogen moves from the cytoplasm to the nucleus, therefore the nuclei of such cells in ordinary micropreparations look bright, optically empty (“ holey ” nuclei). In the nuclei of hepatocytes, glycogenolysis is less intense than in the cytoplasm, and the cells manage to preserve glycogen for their own needs.

In kidneys, on the contrary, glycogen synthesis is significantly enhanced by tubular epithelial cells. This is due to the presence in the primary urine of a large amount of glucose ( glucosuria ). By reabsorbing glucose, the cells of the renal tubule epithelium, mainly the loop of Henle and the distal segments, synthesize glycogen from it, so the tubular epithelium is rich in this polysaccharide ( glycogenous renal tubule infiltration ). Клетки при этом увеличиваются, цитоплазма их становится светлой. Зёрна гликогена выявляются также в просвете канальцев.

Наследственные формы слизистой дистрофии

Типичным примером наследственной слизистой дистрофии является муковисцидоз .

Муковисцидо́з ( кистозный фиброз ) — заболевание с аутосомно-рецессивным типом наследования, при котором происходит загустевание слизистых секретов экзокринных желёз. Наиболее часто в процесс вовлекаются лёгкие и кишечник ( лёгочная , кишечная и кишечно-лёгочная формы заболевания), реже — поджелудочная железа, билиарный тракт, слюнные, слёзные и потовые железы. Основным морфологическим проявлением муковисцидоза является образование множественных ретенционных кист экзокринных желёз. Ретенцио́нной кисто́й называется резко расширенный выводной проток железы за счёт накопления в нём секрета (от лат. retentio — задержка). При муковисцидозе ретенция секрета обусловлена его загустеванием, в результате чего он блокирует дистальный отдел выводного протока. Увеличивающиеся кисты сдавливают паренхиму органа, вызывая с течением времени её атрофию и, следовательно, функциональную недостаточность. Вокруг кист при этом разрастается фиброзная ткань, поэтому муковисцидоз также называют кистозным фиброзом . Наиболее тяжёлые изменения возникают в лёгких, кишечнике и печени. В лёгких густая слизь обтурирует бронхи, вызывая ателектазы и способствуя развитию инфекционных осложнений. В кишечнике густой меконий приводит к мекониальной тонкокишечной непроходимости ( мекониальный илеус ). Густой меконий, длительно сдавливая стенку кишки, может приводить к нарушению кровообращения в ней и к перфорации с последующим формированием мекониального перитонита . В печени загустевание желчи сопровождается холестазом, завершающимся билиарным циррозом .

Существует аргументированная точка зрения, согласно которой муковисцидоз рассматривается как приобретённое, а не наследственное заболевание. Он вызван дефицитом ряда микроэлементов, прежде всего селена , в антенатальном периоде.

Приобретённые формы слизистой дистрофии

К приобретённым формам слизистой дистрофии относятся (1) осложнения катарального воспаления вследствие чрезмерной секреции слизи и (2) проявления коллоидной дистрофии .

Острое катаральное воспаление (или обострение хронического) может сопровождаться гиперпродукцией слизи, которая обтурирует выводные протоки желёз или бронхи. Затруднение оттока слизи по протоку в ряде случаев приводит к развитию ретенционной кисты . Обтурация слизью бронха может завершиться появлением ателектаза .

Колло́идная дистрофи́я — накопление в ткани ряда органов слизеподобных веществ ( мукоида , псевдомуцинов ), которые при уплотнении принимают вид коллоида. Примером коллоидной дистрофии является коллоидный зоб .

• Патологическая анатомия
• Паренхиматозные диспротеинозы
• Альтеративные процессы
• Деструктивные процессы
• Естественный апоптоз
• Мезенхимальные дистрофии
• Мезенхимальные диспротеинозы
• Смешанные дистрофии
• Эндогенные пигменты
• Нарушения кровообращения
• Воспалительный ответ
• Иммунопатологические процессы
• Процессы приспособления и компенсации
• Опухолевый рост
• Этиология злокачественных опухолей

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