Proteins form essential and distincitive contituents of living tissue.
Some disease processes show disturbance of the nature and or guantity of intracelular protein substances or the abnormal apperance of abnormal protein material in the tissue spaces or cells.
These conditions are:
Cloudy swelling (albuminous degeneration, parenchymatous degeneration): most frequent and the mildest and also the most easily reversible change. Many organs may show this change but the best is seen in kidneys (epitelium of proximal convoluted tubules), liver (hepatocytes) and heart (muscles fibers).
Microscopicly the cells are swollen (increased water content) and cytoplasm has cloudy appearence and contains granules of protein which can be fine or coarse.
It is result of variety of injurious conditions (acute infection, fevers, certain poisons, toxins, burns, anoxemia, inanition, sudden excessive demand on an organ and as well early autolytic changes)
Hydropic degeneration: much greater of increased water content in a cell. There is not sharp line between cloudy sweeling and mild hydropic degeneration except that in hydropic degeneration is the granularity not the prominent feature.
Microscopicly the cells are markedly swollen, pale, clear and vacuolated or reticulated in appearence.
It can be seen after intravenous administration of hypertonic sucrose solution, what causing hydropic degeneration of convoluted tubullar cells.
Hyaline degeneration: Hyaline is translucent, homogeneous material that stain with eozin. Similar to colagen. Hyalins can be originaly from connective tissue or epitelium.
The most common type of hyalin (from connective tissue) is evident in any old scare tissue. May follow any chronic inflamation. Hyalinization of the wall of vessels is characteristic feature of aterosclerosis, and as well can be evident in vessels of atrofic organs.
Next type of hyalin can occur within the cells. For instance in severe injuries of the kidneys, small hyalin droplets are prominent in the epithelial cells of convoluted tubules.
Hyalin masses within hepatocytes can be seen in alcoholic cirhosis. (called Malory bodies). In degenarating plasma cells in chronic inflammatory lesions contain hyaline masses (Russel-Fuchs bodies).
Hyalin casts inside renal tubules composed of coagulated protein, in a cases of abnormal permeability of glomeruli to protein.
Fibrinoid degeneration: In a case of artheriolosclerosis and artheriolonecrosis of many organs where is wall of the vesel damaged from various reasons. Plasma from a blood is leaking to the wall and proteins of the plasma start coagulating and homogenazing. After affected parts of the wall have hyalin look.
Amyloid is hyalin-like material that accumulates between parenchymatous cells and in connective tissue. From other hyalins can be distinguished by special staining (PAS, Iodine, Metachromatic dyes as Methyl violet, gentian violet, Congo red). Gross recognition of amyloids in tissues can be provided by Lugol´s solution (iodine). Amyloids area become brown colored. And if 1% sulfuric acid is applied after iodine color will change to blue.
Amyloidosis can be classified:
Secondary amyloidosis: most common form, associated with chronic infestions, chronic inflamations such as tuberculosis, osteomyelitis, rheumatoid athritis... . The most affected organs are spleen, kidneys, liver, adrenal glands.
Primary amyloidosis: absence of know preceding predisposing disease. Tends to involve tissues of mesenchymal origin rather then the parenchymatous tissues. The most affected organs are muscles of the tonque and heart, spleen, liver, kidneys, GIT). Usually affected are middle age persons and disease is developed slowly. Localized amyloidosis forming tumor like nodules in respiratory tract, tonque, pharynx, thyroid, etc.. In eldery diabetics we can found amyloid in the islets of Langerhans of the pancreas.