Metaplasy

In pathological anatomy one speaks about metaplasy in front of the transformation of a cellular fabric differentiated into another differentiated cellular fabric. It is about an adaptive and reversible phenomenon which generally occurs in answer to a repeated and prolonged tissue aggression (ignition, mechanical or chemical irritation, infection), the fabric of replacement being armed better than original fabric against the aforementioned aggression.

In the metaplasy the structure and the function of new fabric are strictly normal, which distinguishes it from the dysplasy (or précancéreux state), although it can evolve secondarily to this stage in the event of persistence of the aggression.

Examples of metaplasy in human pathology

The metaplasy can be marked only by the microscopic examination of a tissue taking away. In human pathology one meets it mainly in four situations:

Bronchi

The chronic exposure to the smoke of Tobacco and/or other carcinogenic substances is responsible for the transformation of the glandular epithelium normal of the bronchial mucous membrane into epithelium malpighien (metaplasy malpighienne). The following stage is the appearance of a dysplasy, then of a Carcinome malpighien.

Cervix

The infection by a papillomavirus can lead to the transformation of the cylindrical epithelium normal of the internal part of the Cervix into epithelium malpighien (metaplasy malpighienne). Such a metaplasy can evolve to a cervical dysplasy then towards a cervical carcinome malpighien. The Smear of tracking, carried out periodically according to the recommendations in force, in particular sticks to seek this metaplasy, in order to allow the assumption of responsibility early and adapted of the patient.

Esophagus

In the pathological Backward flow gastro-œsophagien, the mucous membrane of the lower third of the esophagus is exposed in a chronic way to the acid pH of the gastric liquid, from which it is not protected. One can attend the transformation of the normal epithelium malpighien into a glandular epithelium of intestinal type (intestinal metaplasy), giving a Endobrachyœsophage (or esophagus of Barett), which can in certain case evolve to a Adénocarcinome and thus requires an endoscopic monitoring .

Stomach

A metaplasy similar to that described above for the esophagus can be met in edge of a gastric ulcer, in particular when Helicobacter pylori is in question. The possible evolution towards a cancer justifies here also an endoscopic monitoring.

Other examples

The metaplasy can meet in all fabrics (metaplasy myéloïde, osseous metaplasy, etc)

Random links: