Carbohydrate Dystrophies
This group of pathologies is based on disturbances in carbohydrate metabolism, specifically polysaccharides (glycogen and mucopolysaccharides) and glycoproteins (mucin and mucoids).
Polysaccharide metabolism disorders can manifest in three main variants:
- Decreased carbohydrate content in cells. A classic example is the depletion of glycogen stores in diabetes mellitus.
- Complete absence of carbohydrates, characteristic of aglycogenoses.
- Accumulation of excess carbohydrates, observed in glycogen infiltration and various glycogenoses.
A separate category comprises glycoprotein metabolism disorders, also termed mucous degenerations. These are characterized by the excessive accumulation of mucins and mucoids, causing affected tissues to acquire a characteristic mucous consistency.
Dyspigmentoses (Pigmentary Dystrophies)
Cellular pigments are chromoproteins — complex compounds consisting of a protein and a chromophore. Disturbances in their metabolism are called dyspigmentoses. These conditions are differentiated based on several key criteria.
By origin, they are divided into primary (hereditary and congenital) and secondary (acquired postnatally due to pathogenic agents).
By developmental mechanism, dystrophies are distinguished due to:
- Defects in pigment metabolism enzymes (enzymopathies).
- Alterations in the activity of enzymes responsible for pigment transport across cell membranes.
- Direct damage to cell membranes.
- Excessive accumulation of pigments within phagocytic cells.
- By chemical structure of the pigment, hemoglobinogenic (iron-dependent), proteinogenic (tyrosinogenic), and lipidogenic (lipoproteinogenic) disorders are distinguished.
Clinical manifestations may include the appearance of a pigment that should not normally be present, as well as an excess or deficiency of a physiological pigment. The process can be local (regional) or general (systemic).
Mineral Metabolism Disorders and Thesaurismoses
Mineral dystrophies are associated with disturbed ion metabolism (calcium, potassium, iron, zinc, copper) and manifest as the intracellular accumulation of excess salts. Clinically significant examples include calcinosis, sideroses (iron metabolism disorders), and copper deposition in hepatolenticular degeneration (Wilson's disease).
Thesaurismoses (storage diseases) are conditions in which cells accumulate an excess of various substances, disrupting metabolic and plastic processes, as well as cell structure and function. Virtually all thesaurismoses result from hereditary enzymopathies with an autosomal recessive inheritance pattern.
Lysosomal and peroxisomal storage diseases are distinguished. Classification is based on the type of accumulating substances:
- Lipid (lipidoses) and glycogen (glycogenoses) — the most common forms.
- Amino acid and nucleoprotein.
- Mucopolysaccharide (mucopolysaccharidoses) and mucolipid (mucolipidoses).
Dysplasia and Cell Death
Dysplasia is an impairment of cell differentiation accompanied by persistent changes in its structure, metabolism, and function. Differentiation is dictated by the genetic program, and its realization depends on the interaction between the nuclear genome, cytoplasm, microenvironment, and the influence of biologically active substances. With the same genetic aberration, the manifestations of dysplasias can vary. In clinical practice, many cellular dysplasias are considered precancerous states as they underlie tumor growth.
The final stage of cellular dystrophies or the consequence of direct destructive factors is necrosis — the irreversible cessation of vital activity in a severely damaged cell. Necrosis is always accompanied by perifocal inflammation.
It is preceded by two stages:
- Paranecrobiosis (Paranecrosis) — metabolic and structural changes are still reversible.
- Necrobiosis — changes become irreversible and lead to cell death.
In addition to necrosis and apoptosis, modern data identify specific variants of cell death: necroptosis, pyroptosis, and ferroptosis. Cell death can also occur under physiological conditions (e.g., elimination of spent immunocytes or lactocytes).