Currently, all sorts of diseases are not encountered in medicine. Connective tissue diseases, in particular hyalinosis, are no exception. This is the growth of hyaline in the connective tissue, forming dense masses that resemble cartilage. This pathology is observed in various diseases, for example, hypertension, lupus erythematosus, atherosclerosis, diabetes mellitus, and so on. It is characterized by an increase in the permeability of blood vessels and body tissues, as well as the impregnation of tissues with plasma proteins. In this case, human vessels have a narrowed lumen and resemble dense tubes in their structure. This process is irreversible, but in some cases partial resorption of hyaline is possible. In some cases, this pathology can be attributed to a physiological process of the body in old and mature age. This could be, for example, hyalinosis of the vessels of the spleen, etc.
Problem Definition
Hyalinosis is a pathology in which hyaline (fibrillar protein) is deposited in the walls of blood vessels and connective tissue in the form of dense translucent masses. Hyalin, which is a protein, contains fibrin, plasma proteins, lipids and immunoglobulins. It is not affected by acids, enzymes and alkalis. Currently, hyalinosis is a disease that is very common and is observed in most elderly people who have hypertension, hypertension or diabetes. The vessels are affected to a greater extent, the connective tissue is affected to a lesser extent. With this pathology, the tissue becomes denser, so the disease is classified as a type of sclerosis.
The emergence and development of pathology
Morphogenesis of hyalinosis is very complex and depends on the type of pathology (vessels, connective tissue or serous membranes). The main thing in its formation is the destruction of cells of fibrous structures and leakage of blood vessels as a result of pathological processes in the immune and nervous systems, metabolism. In this case, hyaline is formed from the smooth muscle cells of the vessel walls. In most cases, it can appear as a consequence of various diseases: hypertension, rheumatism, inflammatory processes, necrosis or sclerosis. As a result of sclerosis, this pathology forms in scars and adhesions, vessel walls, or is involved in the formation of blood clots. This happens due to metabolic disorders in connective tissue. There is also a method in which the capsule increases in volume and is saturated with proteins.
Vascular hyalinosis
Small arteries and areolas are affected by this pathology. It occurs as a result of the destruction of the endothelium and cell membranes that line the walls of blood vessels. In this case, the membranes of the vessels become thinner, they turn into thickened tubes with a narrowed or closed lumen. This process is most often observed in the brain, kidneys, pancreas and this manifestation is typical in hypertension, diabetes mellitus and disorders of the human immune system. How the physiological process occurs in the spleen in older people.
Types of vascular hyalinosis
In medicine, it is customary to distinguish three types of vascular hyalinosis:
- Simple, characterized by the occurrence of plasma leaving the bloodstream. This phenomenon is often observed in atherosclerosis and hypertension.
- Lipohyalin, which contains lipids and is characteristic of people who suffer from diabetes.
- Complex hyalinosis, which consists of immunoglobulin, fibrin and is typical for people with diseases of the immune system, rheumatism.
As a result, hyalinosis develops and hypertension becomes wrinkled and has a fine-grained surface.
Consequences
With vascular hyalinosis, the consequences are irreversible, so the prognosis is unfavorable. Pathology leads to deformation and atrophy of the organ, as a result of which its failure develops and hemorrhages (stroke) appear. In the case of connective tissue hyalinosis, partial resorption of hyaline is possible, so to some extent the pathological process may be reversible. This applies, for example, to the mammary glands. This pathology can also lead to organ failure. As for scars, there are no special disorders observed here, but only a cosmetic defect.
Clinical picture
Vascular hyalinosis does not manifest itself clinically, with the exception of damage to the vessels of the fundus, which can be determined using ophthalmoscopy. Small arteries appear thickened and curved. The connective tissue affected by this disease is dense, inelastic, and cream-colored. This is clearly visible in keloid scars and heart valves. When the serous membranes are damaged, the tissue thickens and takes on a milky hue. If there is a liver, then these organs will look as if they were doused with sugar icing. In this case, the disease will be called glaze spleen or glaze liver.
The invisible picture of pathology
With this pathology, thickening of the walls of the arteries is observed due to the accumulation of hyaline masses in them, which partially or completely close the lumen. In this case, the renal tangles are replaced by this mass. In pathologies of connective tissue and serous membranes, the presence of hyaline masses with blood glycoproteins is visible. The narrowing of the lumen of the vessels leads to barotrauma, which is not prevented by contraction of the areola, since it will lose this ability. This leads to the saturation of tissue areas that are supplied with blood by plasma, so it loses its function. Thus, hyalinosis of the renal tangles gradually develops, chronic renal failure and retinopathy appear, which leads to complete blindness. Since hyalinosis is also a pathology in connective tissue, if it occurs in the heart valves, this contributes to their deformation and leads to their insufficiency. Pathology of serous membranes is most often detected during operations or autopsy. If it is found in the spleen or liver, this can lead to the filling of these organs with blood, stretching of their capsule and the appearance of pain. Lipids and salts are quite often deposited in the tissue as a result of its breakdown into simple chemical compounds.
Diagnostics
To identify hyaline, eosin staining is performed, and it will have a pink color. Van Gieson staining will have a result depending on the age of the patient (from yellow to red). The dyes used here are fuchsin and picric acid. The appearance of hyaline in dead tissue is indicated by thrombotic masses and inflammatory exudate. For diagnostic purposes, histological studies are carried out, and hyalinosis is observed in the connective tissue. Tissue necrosis occurs, which is often accompanied by rupture of the vascular wall, the appearance of hemorrhages and thrombosis. Under a microscope, you can detect swelling, cell atrophy, loss of elasticity of blood vessels, hardening of organs, and changes in their color. Externally, the tissues affected by hyalinosis are not changed.
Differential diagnosis
It is necessary to distinguish between physiological hyalinosis, which appears as a result of aging of the body, and a pathological process. This disease is also similar to the transformation of dead tissue and secretion products. It must be remembered that pathological processes in the uterus and mammary glands are reversible, since the functions of these organs are enhanced.
Forecast
The outcome of segmental hyalinosis is renal failure. In rare cases, nephrotic syndrome occurs, which is inherited. Nephritis is often combined with pathologies of kidney development. Children mainly die due to failure of this organ.
Thus, hyalinosis is changes in connective tissue that lead to pathologies and are a consequence of various diseases. This process is also observed during the aging of the body and is physiological in nature.
Hyalinosis
(as a type of stromal vascular dystrophy).
(according to V.V. Serov, M.A. Paltsev)
Stromal-vascular (mesenchymal) dystrophies develop as a result of metabolic disorders in connective tissue and are detected in the stroma of organs and the walls of blood vessels.
- Characterized by accumulation in the tissues of translucent dense masses resembling hyaline cartilage.
- Occurs as a result of fibrinoid swelling, plasmorrhagia, sclerosis, necrosis.
- Hyaline - complex fibrillar protein.
- The mechanism of hyaline formation consists of destruction of fibrous structures and impregnation of them with fibrin and other plasma components(globulins, beta-lipoproteins, immune complexes, etc.).
Highlight hyalinosis of the connective tissue itself and vascular hyalinosis; both of these types of hyalinosis can be widespread and local.
An example of local hyalinosis of the connective tissue itself, which developed as a result of mucoid swelling and fibrinoid changes, is hyalinosis of the heart valves in rheumatism (rheumatic heart disease).
Macroscopic picture: the heart is enlarged, the ventricular cavities are expanded. The mitral valve leaflets are dense, whitish in color, fused together and sharply deformed. The atrioventricular opening is narrowed. The chordal filaments are thickened and shortened.
There are 3 types of vascular hyaline:
A) simple hyaline- occurs as a result of plasmorrhagia of unchanged plasma components (more common in hypertension, atherosclerosis);
b) lipohyalin — contains lipids and beta-lipoproteins (most typical for diabetes mellitus);
V) complex hyaline- is built from immune complexes, fibrin and collapsing structures (characteristic of diseases with immunopathological disorders, for example, rheumatic diseases).
- Widespread hyalinosis of arterioles occurs in hypertension and diabetes mellitus as a result of plasmorrhagia.
- In hypertension, due to hyalinosis of arterioles, arteriolosclerotic nephrosclerosis, or primary wrinkled buds, develops: small dense buds with a fine-grained surface and a sharply thinned cortical layer.
Widespread hyalinosis of small vessels (mainly arterioles) underlies diabetic microangiopathy.
|
Rice. 6, 7. Moderate and severe hyalinosis of the walls of the renal arterioles. Staining: hematoxylin-eosin. Magnification x250. |
||
|
Rice. 8-10. Severe hyalinosis of the walls of the afferent arterioles of the renal glomeruli. Severe sclerosis and hyalinosis of the glomeruli (Fig. 9, 10). Staining: hematoxylin-eosin. Magnification x250. |
||
|
Rice. 11-16. Moderate and severe hyalinosis of the walls of the central arteries of the lymphatic follicles of the spleen. In a number of them, atrophy of the lymphatic follicles and delymphatization of the white pulp. Hematoxylin-eosin. Magnification x250. |
||
Rice. 11. Fibrinoid swelling.
A- fibrinoid swelling and fibrinoid necrosis of the capillaries of the renal glomeruli (systemic red
lupus); b - electron diffraction pattern: in the fibrinoid among the swollen ones that have lost their transverse striations
collagen fibers (KlV), fibrin mass (F). x 35000 (according to Gieseking).
ny (fibrinoid changes in connective tissue in rheumatic diseases
yah; capillaries of the renal glomeruli with glomerulonephritis), angioneurotic
chemical (fibrinoid of arterioles in hypertension and arterial hy-
pergensia). In such cases, fibrinoid swelling is widespread
nenny (systemic) nature. As a manifestation of inflammation, especially
chronic, fibrinoid swelling occurs locally (fibrinoid
in the appendix with appendicitis, in the bottom of a chronic gastric ulcer,
trophic skin ulcers, etc.).
As a result of fibrinoid changes, necrosis develops, replacement of the focus
destruction by connective tissue (sclerosis) or hyalinosis.
Meaning fibrinoid swelling is enormous. It leads to disruption
and often the cessation of organ function (for example, acute renal failure)
sufficiency in malignant hypertension, characterized by fibril-
noid necrosis of glomerular arterioles).
With hyalinosis (from the Greek hyalos - transparent, glassy), or
hyaline dystrophy, in the connective tissue one-
native translucent dense masses (hyaline) 2 resembling hyaline
cartilage. The appearance of hyaline droplets in the cytoplasm (hyaline-droplet di-
strophy) has nothing to do with hyalinosis.
Hyalin is a fibrillar protein, in the formation of which a major role is played
belongs to plasma proteins, in particular fibrin. With immunohistochemical
In a study, not only fibrin is found in hyaline, but also the composition
nents of immune complexes (immunoglobulins, complement fractions),
as well as lipids. Hyaline masses are resistant to acids,
alkalis, enzymes, stain well with acidic dyes (eosin,
sour fuchsin), picrofuchsin are colored yellow or red,
CHIC-positive.
Mechanism hyalinosis is complex. The leaders in its development are destructive
tion of fibrous structures and increased tissue-vascular permeability
(plasmorrhagia) in connection with angioneurotic (dyscirculatory), metabolic
personal and immunopathological processes. Associated with plasmorrhagia
impregnation of fabric with plasma proteins and their adsorption on modified fibers
ny structures with subsequent precipitation and protein formation -
hyaline. Hyalinosis can develop as a result of various processes: plasmatic
chemical impregnation, fibrinoid swelling (fibrinoid), inflammation,
necrosis, sclerosis.
Classification of hyalinosis. There are vascular hyalinosis and intrinsic hyalinosis.
specifically connective tissue. Each of them can be distributed
local (systemic) and local.
Vascular hyalinosis. Mostly small-sized ones undergo hyalinosis.
some arteries and arterioles. It is preceded by damage to the endothelium, argyro-
philic membranes and smooth muscle cells of the wall and permeation of its plasma-
my blood.
Microscopic picture: hyaline falls out in the subendothelial pro-
wandering, hyaline masses push outwards and destroy the elastic
plate, lead to thinning of the middle shell, resulting in arterial
riols turn into thickened dense glassy tubes with sharp
narrowed or completely closed lumen (Fig. 12).
Hyalinosis of small arteries and arterioles is systemic in nature, but most
more expressed in the kidneys, brain, retina, half-gastric gland
ze, skin. It is especially characteristic of hypertension and hypertension
ical conditions (hypertensive arteriolohyalinosis), diabetic mi-
croangiopathies (diabetic arteriolohyalinosis) and diseases with impaired
niyami immunity. As a physiological phenomenon, local arterial hyalinosis
observed in the spleen of adults and elderly people, reflecting the functional
nal-morphological features of the spleen as a depository organ
blood.
Vascular hyaline is a substance of hematogenous nature. In his education
not only hemodynamic and metabolic, but also immune
mechanisms. Guided by the peculiarities of the pathogenesis of vascular hyalinosis, you
There are 3 types of vascular hyaline: 1) simple, emerging
due to insudation of unchanged or slightly changed plasma components
blood; occurs more often in benign hypertension
pain, atherosclerosis and in healthy people; 2) l i p o g i a l i n containing
lipids and B-lipoproteins; found most often in diabetes mellitus;
3) complex hyaline, built from immune complexes, fibrin
and collapsing structures of the vascular wall (see Fig. 12), characteristic of
diseases with immunopathological disorders, for example, rheumatic
ski diseases.
Hyalinosis of the connective tissue itself. Developing
usually results from fibrinoid swelling leading to collagen destruction
and impregnation of the tissue with plasma proteins and polysaccharides.
Microscopic picture: connective tissue bundles swell,
become fibrillar and merge into a homogeneous dense cartilage-like
mass; cellular elements are compressed and undergo atrophy.
A similar mechanism for the development of systemic connective tissue hyalinosis
especially common in diseases with immune disorders (rev-
matic diseases). Hyalinosis may complete fibrinoid changes
Rice. 12. Hyalinosis of the vessels of the spleen.
A - the wall of the central artery of the splenic follicle is represented by homogeneous hyaline-like
by the masses; 6 -
fibrin among hyaline masses when stained using the Weigert method; V- fixation in hyaline
immunoglobulin class G (antibody) immune complexes; fluorescence microscope; G - electro-
nogram: hyaline masses (G) in the wall of the argeriole; En - endothelium; Etc - arteriole lumen. x 15000.
in the bottom of a chronic gastric ulcer, in the vermiform appendix with appendix
quote; similar to the mechanism of local hyalinosis in the focus of chronic inflammation
scorching.
As a peculiar outcome of sclerosis, hyalinosis has mainly the following:
same local character: it develops in scars, fibrous adhesions, serous
cavities, vascular wall with atherosclerosis, involutional sclerosis
teria, when organizing a blood clot, in capsules (Fig. 13), tumor stroma, etc.
Hyalinosis in these cases is based on metabolic disorders in the connective tissue
fabrics. A similar mechanism has hyalinosis of necrotic tissues and fi-
brinose overlays.
Appearance organs with hyalinosis are usually preserved. However, in those cases
In teas, when the process is expressed sharply, the tissue becomes pale, dense and
translucent. Hyalinosis can lead to deformation and shrinkage of the organ
(for example, the development of arteriolosclerotic nephrocirrhosis, valvular
rock of the heart).
 |
Rice. 13. Hyalinosis of the liver capsule -
glazed liver (top view).
Exodus in most cases
teas hyalinosis is unfavorable -
ny, but possibly also rassas-
formation of hyaline masses. So,
hyaline in scars, the so-called
keloids, may be susceptible
to resist loosening and disintegration -
Vania. Let's reverse hyalinosis
mammary gland, and dis-
shedding of hyaline masses
comes in conditions of hyperfunction
tions of glands. Sometimes hyalinisi-
the fabric becomes slimy...
Functional meaning hyalinosis varies depending on its localization
tion, degree and prevalence. For example, in scars it may not cause
no special disorders. Widespread hyalinosis, on the contrary, leads to significant
significant functional impairment and may have severe after-effects
effects, as observed, for example, with rheumatism, scleroderma,
hypertension, diabetes and other diseases.
Details
Mesenchymal dystrophies develop as a result of metabolic disorders in connective tissue and are detected in the structure of organs and the walls of blood vessels. In case of metabolic disorders in the connective tissue, mainly in its intercellular substance, metabolic products accumulate, which can be carried with blood and lymph, be the result of perverted synthesis, or appear as a result of disorganization of the main substance and fibers of the connective tissue.
1. Stromal-vascular dysproteinoses
Dystrophies of this type include mucoid swelling, fibrinoid swelling, hyalinosis, and amyloidosis.
Often, mucoid swelling, fibrinoid swelling and hyalinosis are successive stages of connective tissue disorganization. This process is based on the accumulation of blood plasma products in the main substance as a result of increased tissue-vascular permeability ( plasmorrhagia), destruction of connective tissue elements and the formation of protein-polysaccharide complexes. Amyloidosis is distinguished by the fact that the complex formed includes an abnormal protein that is synthesized by amyloidoblasts.
1) Mucoid swelling
Superficial and reversible disorganization of connective tissue. In this case, accumulation and redistribution of glycosaminoglycans occur in the main substance due to an increase in the content of primarily glucuronic acid. Since glycosaminoglycans have increased hydrophilic properties, their accumulation causes an increase in tissue and vascular permeability. As a result, plasma proteins (mainly globulins) and glycoproteins are mixed with GAGs. Hydration and swelling of the main interstitial substance develop.
Microscopy: the main substance is basophilic. A phenomenon arises metachromasia– change in the state of the main interstitial substance due to changes in pH with the accumulation of chromotropic substances. Collagen fibers swell and usually retain their bundle structure. They become less resistant to the action of collagenase.
Changes may be accompanied by the appearance of lymphocytic, plasma cell and histiocytic infiltrates.
This type of swelling occurs in various organs and tissues, but more often in the walls of arteries, heart valves, endocardium, epicardium, that is, where chromotropic substances are found normally (however, in pathology, their number increases sharply).
Appearance: the tissue or organ is preserved.
Causes: hypoxia, infectious and allergic diseases, rheumatic diseases, atherosclerosis, endocrinopathy, etc.
Exodus: twofold. Either complete tissue restoration or transition to fibrinoid swelling.
2) Fibrinoid swelling.
There is profound and irreversible disorganization of connective tissue, which is based on the destruction of its basic substance and fibers, accompanied by a sharp increase in vascular permeability and the formation of fibrinoid. Fibrinoid– a complex substance, the composition includes proteins and polysaccharides of decaying collagen fibers, the main substance and blood plasma, as well as cellular nucleoproteins. An essential component is fibrin.
Microscopy: bundles of collagen fibers impregnated with plasma become homogeneous, forming insoluble, strong eosinophilic compounds with fibrin. Tissue metachromasia is not expressed or expressed weakly (since the GAGs of the main substance are depolymerized).
Appearance: Externally, organs and tissues change little.
Causes: most often this is a manifestation of infectious-allergic, autoimmune and angioedema reactions. In such cases, swelling is systemic. Local fibrinoid swelling can occur during inflammation, especially chronic inflammation.
Exodus: characterized by the development of fibrinoid necrosis, replacement of the focus of destruction with connective tissue (sclerosis) or hyalinosis.
Such swelling leads to disruption, sometimes to cessation of organ function.
3) Hyalinosis
In the connective tissue, homogeneous translucent dense masses are formed, reminiscent of hyaline cartilage. At the same time, the fabric becomes denser.
In the development of hyalinosis, the leading role is played by the destruction of fibrous structures and an increase in tissue-vascular permeability. Plasmorrhagia is associated with the impregnation of tissue with plasma proteins and their adsorption on altered fibrous structures, followed by precipitation and the formation of hyaline. Smooth muscle cells take part in the formation of vascular hyaline. Hyalinosis can develop as a result of various processes: plasma impregnation, fibrinoid swelling, inflammation.
There are:
A) vascular hyalinosis
Hyalinosis occurs mainly in small arteries and arterioles. It is preceded by damage to the endothelium, its membrane and smooth muscle cells of the wall and its saturation with blood plasma.
Microscopy: hyaline is found in the subendothelial space6, it pushes outward and destroys the elastic lamina, the tunica media becomes thinner, and in the phiale the arterioles turn into thickened glass tubes with a sharply narrowed or completely closed lumen.
This hyalinosis is systemic in nature, however6 it is most pronounced in the kidneys, brain, retina, pancreas, and skin. Characteristic of hypertension, diabetic microangiopathy and diseases with impaired immunity. As a physiological phenomenon, local arterial hyalinosis is observed in the spleen of adults and elderly people (reflects the functional and morphological characteristics of this organ - blood deposition).
Vascular hyaline- a substance of predominantly hematogenous nature. Guided by the peculiarities of the pathogenesis of vascular hyalinosis, the following are distinguished:
- simple vascular hyaline
Occurs as a result of insudation of unchanged or slightly changed components of blood plasma. This type of hyaline is more common in patients with benign hypertension, atherosclerosis, as well as in healthy people.
- lipohyalin
Contains lipids and beta-lipoproteins. This type of hyaline is often found in diabetes mellitus.
- complex hyaline
It is built from immune complexes, fibrin and collapsing structures of the vascular wall. This hyaline is typical for patients with immunopathologies, for example, rheumatic diseases.
B) hyalinosis of the connective tissue itself
It develops, as a rule, as a result of fibrinoid swelling, leading to the destruction of collagen and saturation of the tissue with plasma proteins and polysaccharides.
Myometrial hyalinosis is of great clinical importance. After a Caesarean section, a scar remains on the uterus; hyaline is deposited in the cells at the border with the muscle. If a woman gives birth to a second child naturally, a gap will occur.
Microscopy: connective tissue bundles lose fibrillarity, and cellular elements turn into a cartilage-like mass.
Hyalinosis can complete fibrinoid changes in the focus of chronic inflammation. Hyalinosis as an outcome of sclerosis is mainly local in nature: it develops in scars, fibrous adhesions of serous cavities, and the vascular wall in atherosclerosis.
Appearance: with severe hyalinosis, the appearance of organs changes. Hyalinosis of arterioles and small arteries leads to atrophy, deformation and shrinkage of the organ. With hyalinosis of the connective tissue itself, it becomes dense, whitish, and translucent.
Exodus: in most cases unfavorable, however, resorption of hyaline masses is also possible.
4) Amyloidosis
It is accompanied by a profound disruption of protein metabolism, the appearance of abnormal fibrillar protein and the formation of amyloid in the interstitial tissue and walls of blood vessels.
Amyloid is a glycoprotein, the main components of which are fibrillar proteins (F-component, synthesized by amyloidoblasts). They form fibrils . Fibrillar proteins amyloid is heterogeneous:
a) AA protein: not associated with immunoglobulins, formed from its serum counterpart - the SAA protein
b) AL protein: associated with immunoglobulins, its precursor is the light chains of immunoglobulins
c) AF protein: prealbumin is involved in its formation
d) ASC 1 protein - a protein whose precursor is also prealbumin
These fibrillar proteins form complex compounds with blood plasma glucoproteins. This plasma component (P component) of amyloid is represented by rod-shaped structures.
Both F and P components have antigenic properties. Amyloid fibrils and the plasma component enter into compounds with chondroitin sulfates in tissue, and “hematogenous additives” are added to the resulting complex, among which fibrin and immune complexes are of primary importance. All bonds in amyloid are very strong, so the body's enzymes do not act on it.
Classification amyloidosis is based on possible causes, specificity of fibrillar proteins, prevalence, clinical manifestations.
A. For reasons of occurrence:
Primary (idiopathic) amyloidosis
It is characterized by: the absence of a previous or concomitant “causal” disease; damage to predominantly mesodermal tissues - cardiovascular system, skeletal and smooth muscles, nerves and skin; tendency to form nodular deposits, inconstancy of colorful reactions of amyloid substance
Hereditary (genetic, familial) amyloidosis
Hereditary amyloidosis with predominant kidney damage is characteristic of a periodic disease (familial Mediterranean fever), which is more often observed among representatives of ancient peoples (Jews, Armenians, Arabs).
Secondary (acquired) amyloidosis
Unlike other forms, it develops as a complication, and not as an independent disease. This amyloidosis is caused by chronic nonspecific inflammatory lung diseases, tuberculosis, osteomyelitis, malignant neoplasms, and rheumatic diseases.
This amyloidosis is usually generalized and occurs most often.
Senile amyloidosis
Typical lesions are the heart, arteries, brain, and islets of Langerhans. These changes cause physical and mental degradation of senility. With senile amyloidosis, local forms are most common, although generalized senile amyloidosis also occurs.
B. According to the specificity of fibrillar proteins:
AL amyloidosis
Includes primary (idiopathic) amyloidosis and amyloidosis with “plasma cell dyscrasia”, which combines paraproteinemic leukemia, malignant lymphomas, etc.
Always generalized with damage to the heart, lungs and blood vessels.
AA amyloidosis
Covers secondary amyloidosis and McClell's and Welsh's diseases. Also generalized, but predominantly affects the kidneys.
AF amyloidosis
Hereditary, represented by familial amyloid nephropathy. The peripheral nerves are mainly affected.
ASC 1 amyloidosis
Senile generalized or systemic with predominant damage to the heart and blood vessels.
B. By prevalence
- generalized form
Primary amyloidosis, amyloidosis with “plasma cell dyscrasia” (AL), secondary amyloidosis and some types of hereditary (AA), senile systemic amyloidosis (ASC 1).
Local amyloidosis
Combines a number of forms of hereditary and senile amyloidosis, as well as local tumor-like amyloidosis.
D. According to clinical manifestations
- cardiopathic
It is more common in primary and senile systemic amyloidosis.
- nephropathic
For secondary amyloidosis, periodic disease and McClell and Wells disease.
- neuropathic
As a rule, it is hereditary.
Hepapathic
Epinephropathic
- mixed
Secondary amyloidosis.
APUD amyloidosis
It develops in the organs of the APUD system when tumors develop in them (apudomas), as well as in the islets of the pancreas during senile amyloidosis.
Morphological and pathogenesis of amyloidosis
Sometimes the function of amyloidoblasts is performed by macrophages, plasma cells, fibroblasts, etc. In local forms, the role of amyloidoblasts can be played by cardiomyocytes, smooth muscle cells, and keratinocytes.
In secondary amyloidosis (excluding amyloidosis with “plasma cell dyscrasia”), mutations and the appearance of amyloidoblasts can be associated with prolonged antigenic stimulation.
Cellular mutations in “plasma cell dyscrasia” and in tumor amyloidosis are caused by tumor mutagens.
In genetic amyloidosis, we are talking about a gene mutation that can occur at different loci, which is why the composition of amyloid proteins differs. Similar mechanisms probably occur in senile amyloidosis.
Because amyloid fibril protein antigens are extremely weak immunogens, mutating cells are not recognized or eliminated. Immunological tolerance to amyloid proteins develops, which leads to the progression of amyloidosis.
The formation of amyloid protein may be associated with:
Reticular fibers (perireticular amyloidosis)
Amyloid falls out along the membranes of blood vessels and glands, as well as the reticular stroma of parenchymal organs. Characterized by predominant damage to the spleen, liver, kidneys, adrenal glands, intestines, and the intima of small and medium-sized vessels (parenchymal amyloidosis).
Collagen fibers (pericollagenous)
Amyloid falls out along the collagen fibers; the adventitia of medium and large vessels, myocardium, striated and smooth muscles, nerves, and skin are predominantly affected (mesenchymal amyloidosis).
Pathogenesis amyloidosis is complex and ambiguous. The pathogenesis of AA and AL amyloidosis has been best studied.
At AA amyloidosis Amyloid fibrils are formed from the precursor of amyloid fibrillar protein entering the macrophage - the SAA protein, which is synthesized in the liver. The synthesis of SAA is stimulated by the macrophage mediator interleukin-1, which leads to a sharp increase in SAA in the blood. Under these conditions, macrophages do not completely degrade SAA, and amyloid fibrils are assembled from its fragments and invaginates of the plasma membrane of the amyloidoblast. This assembly is stimulated by the amyloid-stimulating factor, ASF, which is found in tissues in the pre-amyloid stage.
So, the magrophage system plays a leading role in the pathogenesis of AA amyloidosis: it stimulates increased synthesis of SAA and is also involved in the formation of amyloid fibrils from degrading protein fragments.
At AL amyloidosis The serum precursor of amyloid fibril protein is the L-chains of immunoglobulins. There are two possible mechanisms for the formation of AL fibrils: 1) disruption of the degradation of light chains with the formation of fragments capable of aggregation and fibrils; 2) the appearance of light chains with special secondary and tertiary structures during amino acid substitutions.
The synthesis of amyloid fibrils can occur not only in macrophages, but also in plasma and myeloma cells that synthesize paraproteins.
Accordingly, the appearance of amyloidogenic light chains of immunoglobulins, the precursor of amyloid fibrils, is associated with the perverted function of the lymphoid system.
Macro and microscopy
The appearance of the organs depends on the extent of the process. If the deposits are small, the appearance of the organ is little changed. With severe amyloidosis, the organ enlarges, becomes very dense and brittle, and has a waxy, greasy appearance when cut.
IN spleen amyloid is deposited in the lymphatic follicles (sago spleen - dense, enlarged, translucent grains on a section) or evenly throughout the entire pulp (sebaceous spleen - enlarged, dense, brown-red, smooth, has a greasy sheen on a section).
IN kidneys amyloid is deposited in the wall of blood vessels, in the capillary loops and mesangium of the glomeruli, in the basement membranes of the tubules and in the stapes. The buds become dense, large, and greasy. As the process progresses, the glomeruli and pyramids are completely replaced by amyloid, the connective tissue grows and amyloid wrinkling develops.
IN liver amyloid deposition is observed along the reticular stroma of the lobules. In the walls of vessels, ducts, connective tissue of portal tracts. Hepatocytes shrink and die. The liver is enlarged, dense, and looks greasy.
IN intestines amyloid falls out along the reticular stroma of the mucosa, as well as in the walls of blood vessels of both the mucous membrane and the submucosal layer. With severe amyloidosis, the glandular apparatus of the intestine atrophies.
IN heart amyloid is found under the endocardium, in the stroma and vessels of the myocardium, as well as in the epicardium along the veins. Deposition leads to amyloid cardiomegaly. The heart becomes dense and greasy.
Exodus amyloidosis is unfavorable.
2. Stromal-vascular lipidoses
They occur when there are disturbances in the metabolism of neutral fats or cholesterol and its esters.
Neutral fats– labile fats that provide the body with energy reserves.
Obesity– an increase in the amount of neutral fats in fat depots, which is of a general nature. It is expressed in abundant deposition of fats in the subcutaneous tissue, omentum, and mesentery. mediastinum, epicardium. Adipose tissue also appears where it is normally absent, for example, in the myocardial stroma and pancreas.
Classification is based on various principles:
A. According to etiology:
Primary form
Its cause is unknown, which is why it is called idiopathic.
Secondary form
Represented by the following types:
Nutritional, the cause of which is physical inactivity and unbalanced nutrition
Cerebral, developing with trauma, tumors, a number of neurotropic infections
Endocrine-Itsenko-Cushing, Froelich syndromes
Hereditary – Lawrence-Moon-Biedl syndrome, Gierke disease
B. By external manifestations:
Symmetrical type
Fats are deposited evenly in different parts of the body.
Accumulation in the subcutaneous tissue of the face, back of the head, neck, upper shoulder girdle, and mammary glands.
Fat is deposited in the subcutaneous tissue of the abdomen in the form of an apron
In the thighs and shins area
B. For excess body weight:
I degree – 20-29% excess body weight
II degree – 30-49%
III degree - 50-99%
IV degree – 100% or more
D. According to the characteristics of morphological changes
The number of adipocytes and their size are taken into account.
Hypertrophic type
Fat cells are enlarged and contain several times more triglycerides than normal ones. The number of adipocytes does not change. Adipocytes are insensitive to insulin, but highly sensitive to lipolytic hormones.
Hyperplastic type
The number of adipocytes increases. The function of adipocytes is not impaired, there are no metabolic changes, and the course of the disease is benign.
Causes and mechanisms of development
Unbalanced nutrition, physical inactivity, disturbances of the central nervous system, endocrine regulation, and hereditary factors are of great importance.
The immediate mechanism of obesity lies in the imbalance of lipogenesis and lipolysis in the fat cell in favor of lipogenesis.
Exodus: Rarely favorable.
Metabolism disorders of cholesterol and its esters.
Such disorders underlie atherosclerosis. At the same time, cholesterol and its esters, but also low-density beta lipoproteins and blood plasma proteins accumulate in the intima of the arteries, which is facilitated by an increase in vascular permeability.
Accumulation leads to destruction of the intima.
As a result, fat-protein detritus is formed in the intima, connective tissue grows, and a fibrous plaque is formed, narrowing the lumen of the vessel.
3. Stromal-vascular carbohydrate dystrophies
May be associated with an imbalance of glycoproteins and glycosaminoglycans.
Slime tissue– dystrophy associated with impaired glycoprotein metabolism. Chromotropic substances are released from bonds with proteins and accumulate in the interstitial substance. In contrast to mucoid swelling, this involves replacement of collagen fibers with a mucus-like mass. Connective tissue, organ stroma, adipose tissue, cartilage become translucent, mucus-like, and their cells become stellate.
Cause: most often due to dysfunction of endocrine jelly, exhaustion (for example, myxedema, mucous edema, mucus of connective tissues with cachexia).
Exodus: The process can be reversible, but its progression leads to colliquation and necrosis.