The tubercular inflammation, as well as I everyone another, develops of the phenomena alteration, exudation, proliferation, resulting to formation tubercular granuloma (tuberculum, tubercular tumour). The term granuloma derived from the diminutive of the Latin term for a grain, granulum, was used Rulolf Virchov [1818] to describe tumours that may ulcerate and give rise to granulation tissue. The tubercular granuloma is not a mere collection of inflammatory cells but an active site of numerous enzymes and cytokines in the very serious process of removing the causative agent – MBT. In formation of tubercular granuloma take part hematogenic (lymphocytes, monocytes, polymorphonuclear leucocytes) and histiogenic (histocytes, macrophages, fibroblasts, reticular cells, endothelium of blood vessels, plasmatic and fat cells). The tuberculum has the following structure. The center of the formation is consisted from tissue detritus (consequence of alteration and necrosis), on periphery fence locates comprised from several layers of epithelial cells. In external layers of tuberculum lymphoid and plasmatic cells in small quantity are found out. Among the epithelioid cells, the large multinuclear gigantic Pirogov-Langhance cells are found out.
The structure of the tuberculum depends, how inflammative process is developed: progresses or, on the contrary, regresses. At decrease of the host resistance to MBT, progression of tubercular inflammation occurs, the tissue exudative reaction develops with occurrence of cheesy necrosis. Cheesy necrosis develops in tuberculum and in surrounded tissue, impregnated by serous-fibrinous exudates. At further progression of specific tubercular inflammation, besides tubercles, the various size focuses of cheesy necrosis appear. At enlargement, the focuses of cheesy necrosis can melt, merge in the large focuses, from which focuses with sites of caseation (infiltrations) are formed. Caseosis is liquefied under the influence of proteolitic enzymes and coughed out. In these regions of the lungs cavities of disintegration and on mucous membranes and skin – ulcer are appeared. Formed, at caseous disintegration, the cavity will be a source of МВТ dissemination in other parts of lungs with formation of the new focuses and cavities.
The special danger is represented by erosion blood vessel participating in blood supply of a site of a lung tissue caseous degeneration. At formation of a cavity blood from the damaged vessel penetrates in bronchi and by them, in other parts of lungs or expectorates with sputum. At high resistant of host the reverse development of inflammation process (regression) takes place. The epithelium cells are turned into fibroblasts, tuberculum turns to scarring. In the further development the focus of necrosis can dissolve, undergo fibrosis, calcification and ossification.