Infiltration (medicine)

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Infiltration describes the penetration of solid or liquid substances, called infiltrates , into biological tissue . The spread of tumor cells or pathogens into a tissue is also known as infiltration. Pathological infiltration must be distinguished from infiltration therapy , in which medicinal substances are injected into small areas of tissue.

Forms of infiltration

In inflammatory processes, immune cells accumulate in the tissue to eliminate infectious agents and waste materials. The resulting inflammatory infiltrates are divided into purulent , eosinophilic , lymphocytic and other forms according to the predominant cell type .

Infiltrative growth is an essential feature that distinguishes malignant from benign neoplasms . A special form here are leukemic infiltrates, which are characterized by a massive penetration of skin and other tissue areas with white blood cells . The spread of the tumor cells can also be reticulate, as in the case of micro carcinomas .

Accumulations of fluids and cellular components in the lungs , such as those that occur in tuberculosis , pulmonary embolism or allergic processes , lead to tissue densification , which is known as lung infiltration (especially in pneumonia ).

In lupus vulgaris , epithelioid cells accumulate in the dermis , which leave apple jelly-like stains under the pressure of a glass spatula. Pathological infiltrates of the intercellular areas can also consist of fluids such as blood plasma , liquor , secretions or exudates .

Occasionally, the increased storage of solids or liquids in cells, as occurs, for example, in fatty degeneration as a result of an insufficient supply of oxygen to the tissue, is also referred to as infiltration.