73. Granulomatous inflammation: definition, causes, types, conditions of formation, mechanisms. Pathological anatomy, outcomes, clinical significance, examples of diseases.

Chronic granulomatous inflammation develops in cases when, for some reason, damaging factors cannot be removed from the body. All granulomas are formed according to a single histogenetic plan. The main structural unit of any granuloma is a macrophage.

The morphogenesis of granuloma consists of 4 stages.

•Accumulation of monocytic phagocytes in the lesion of tissue damage.

•Maturation of these cells into macrophages and formation of macrophage granuloma.

•Maturation and transformation of monocytic phagocytes and macrophages into epithelioid cells and formation of epithelioid cell granuloma.

•Fusion of epithelioid cells (or macrophages) and the formation of giant cells (foreign body cells or Pirogov–Langhans cells) and epithelioid cell or giant cell granuloma.

Giant cells are characterized by significant polymorphism — from 2-3-nuclear to giant symplasts containing 100 nuclei or more. Thus, guided by morphological features, three types of granulomas should be distinguished: 1) macrophage granuloma (simple granuloma, or phagocytoma); 2) epithelioid cell granuloma (epithelioidocytoma); 3) giant cell granuloma. Depending on the level of metabolism, granulomas with low and high levels of metabolism are distinguished. Granulomas with a low level of metabolism are formed by the action of inert substances (inert foreign bodies) and consist mainly of giant cells of foreign bodies. Granulomas with a high level of metabolism appear under the action of toxic irritants (Mycobacterium tuberculosis, leprosy) and consist of epithelioid cell nodules. The etiology of granulomatosis is diverse. There are infectious, non-infectious and granulomas of an unidentified nature. Infectious granulomas are formed in both acute and chronic infectious diseases. Non-infectious granulomas occur in dust diseases (silicosis, talcosis, asbestosis, bissinosis), drug effects (granulomatous hepatitis, oleogranulomatous disease). They also appear around foreign bodies. Granulomas of unknown nature — granulomas in sarcoidosis, Crohn's and Horton's diseases, Wegener's granulomatosis. Granulomas are also divided into specific and non-specific ones. Specific are those granulomas whose morphology is relatively specific to a certain infectious disease, the causative agent of which can be found in granuloma cells during histobacterioscopic examination. Specific granulomas (previously they were the basis of the so-called specific inflammation) include granulomas in tuberculosis, syphilis, leprosy and scleroma.

74. Specific granulomas: definition of the concept, conditions of formation, causes. Macro- and microscopic structure, outcomes, complications, clinical significance.

Granulomas are divided into specific and non-specific ones. The morphology of a specific granuloma is relatively specific to a certain infectious disease, the causative agent of which can be found during histobacterioscopic examination in granuloma cells. Specific granulomas were previously considered the basis of the so—called specific inflammation - granulomas in tuberculosis, syphilis, leprosy and scleroma.

Tuberculous granuloma has a necrosis focus in the center, and a shaft of epithelioid cells and lymphocytes with an admixture of macrophages and plasma cells along the periphery. Pirogov–Langhans giant cells typical of tuberculous granuloma are located between epithelioid cells and lymphocytes (Fig. 5-12, 5-13). When impregnated with silver salts, a network of argyrophilic fibers is found among granuloma cells. A small number of blood capillaries are found only in the outer areas of the tubercle. When stained according to Zil–Nielsen, Mycobacterium tuberculosis is detected in epithelioid and giant cells.

Syphilitic granuloma (gumma) has an extensive focus of coagulation necrosis, to which hydrolases of neutrophilic leukocytes impart adhesive properties. The necrosis zone is surrounded by lymphocytes, plasma cells, macrophages, neutrophilic leukocytes and fibroblasts, single epithelioid cells and giant Pirogov–Langhans type cells. Connective tissue is intensively formed around the granuloma, forming a capsule, near which many small vessels with phenomena of productive inflammation in the walls and proliferating endothelium (endovasculitis) are located in the inflammatory infiltrate. Leprosy granuloma is a nodule consisting mainly of macrophages, lymphocytes and plasma cells. Among macrophages, large cells with fatty vacuoles containing Mycobacterium leprosy packed in the form of balls are isolated — Virchow's leprosy cells. When they disintegrate, they release mycobacteria, freely located among the cells of the leprosy. Scleroma granuloma consists of plasma and epithelioid cells, lymphocytes, among which there are many hyaline balls. The appearance of large macrophages with light cytoplasm — Mikulich cells - is very characteristic. The causative agent of the disease, Volkovich—Frisch sticks, is detected in the cytoplasm. Significant sclerosis and hyalinosis of granulation tissue are characteristic.