The mechanisms of origin and development - the pathogenesis of enlarging the lymph node - are partly due to the functions of the lymph nodes that, with the help of macrophages of their sinuses and stroma, purify the lymph fluid from associated antigens, toxins and products of cellular metabolism. For more details, see Lymph node hyperplasia.
Depending on the cause of the disease and the mechanism of action on lymphoid tissue, the types of this pathology are distinguished: infectious, reactive and malignant. So, with an infection with a current of lymph, phagocytes with entrapped antigens and those killed by inflammatory necrosis of cells get into the nodes and accumulate. For example, in tubercular patients, mycobacterium M. Tuberculosis, which enter the lymph nodes, is absorbed by macrophages with the formation of phagolysomes, formation of granulomas and the development of caseous necrosis of lymphoid tissue.
Granulomatous changes in the lymph nodes (with the displacement of fibrotic lymphoid tissue) are also noted in sarcoidosis, the etiology of which is still unknown to medicine (although autoimmune and genetic causes of its occurrence are not excluded).
In cases of reactive enlargement of the lymph nodes in the lungs, the dominant pathological process is the increased proliferation of their follicles, which is provoked by autoimmune diseases - when the body's immune system produces antigens against healthy cells, as happens, in particular, in systemic lupus erythematosus.
With the increase of lymph nodes in lungs of malignant nature, lymphomas with abnormal cell proliferation are formed. And with metastases, lymphoproliferative disorders are caused by the infiltration of healthy tissues with atypical (cancerous) cells and their proliferation, which leads to pathological morphological changes.