Fibriniai

Fibriniai, commonly translated as fibrinous, is an adjective used in medical pathology to describe tissues, exudates, or lesions that contain or are rich in fibrin, a fibrous protein involved in blood coagulation.

Fibrin is formed when fibrinogen is cleaved by thrombin to create insoluble fibrin, which polymerizes to form a mesh that stabilizes blood clots. In inflammatory processes, plasma fibrinogen leaks into tissues and is converted there, creating a fibrinous exudate that appears as a pale, glassy, eosinophilic layer on serous surfaces.

Fibrinous exudates are commonly seen in serosal inflammation, such as fibrinous pericarditis, pleuritis, and peritonitis. They can organize into scar tissue or adhesions. In the lung, fibrinous pneumonia produces fibrin-rich exudates on alveolar surfaces.

Fibrin is distinct from fibrous tissue, which is collagen-rich and forms durable connective tissue; fibrin is temporary and part of the coagulation process. Histology shows a loose, eosinophilic mesh of fibrin that may be accompanied by inflammatory cells. Resolution involves fibrinolysis: plasmin degrades the fibrin mesh, while macrophages help clear debris; persistent inflammation may promote adhesions or scarring.