Metastasis is the pathological education arising from development in any organ painful process due to the introduction him in the blood or lymph pathogenic agent. The process of moving painful process with the development of the new (secondary) hearth called metastasis.
Disease agents are cells of malignant tumors or pathogens. In the first case are developing tumor metastases (see Tumors, Cancer, Sarcoma), the second - inflammation, the nature of which depends on the characteristics of the infectious agent. Infectious metastases are the basis for the development of sepsis (see), lesions of bones, joints and other organs of lung tuberculosis, etc., In the formation of metastases, plays a significant role embolism (see) carry - pathogenic agent is remote from the primary tumor site. However embolism not always imply the development of metastases, as a great role for reactive properties of tissues, which are pathogenic embolus. Metastasis of tumor - an indicator of malignancy process.
In relation to the primary tumor, which is the source of metastasis, there are coming (regional and distant metastases. Coming detect metastases in the lymph nodes, in which the lymph from the primary area of focus. Distant metastases develop hematogenous route, though lymphogenous way it is. Metastasis may in turn be a source of metastasis with the formation of the so-called child metastases.

Metastasis (from the Greek. metastasis - move) - the pathological education, appeared in an organ or tissue through the introduction of pathogenic beginning from the nearest or distant focus of this process. Pathogenic beginning can be pathogenic microorganisms (infectious metastasis and cell tumors (tumor M). The term "metastasis" sometimes used (without good reason) for the introduction of any inert masses in remote areas of the body. Such, for example, M. coal pigment from the hearth of intrakota, M. lime - from the hearth of calcification.
Metastasis is performed by the introduction of pathogenic beginning of the blood (hematogenous M) or lymph (lymphogenous M). There are still implant metastases, which are essentially straight privivkami from home defeat by contacting healthy surface of the body.
The process of metastasis can be schematically divided into 3 phases: 1) a breakthrough pathogenic agents into the blood or lymph flow; 2) transfer them to the blood or lymph in the direction of their movement (rarely against the movement, when the so-called retrograde M) and drift in the nearest or distant organs (embolic phase M); 3) development of appropriate painful process in the area of embolism. As shown by numerous observations, the development is determined it is the last phase and depends on the properties of the medium in which listed pathogenic elements.