Fibrosis is the formation of excess fibrous connective tissue during a reparative or reactive process.

Fibrosis occurs in organs and tissues (ex. pulmonary fibrosis is fibrosis in the lungs). This can be reactive, benign, or pathological.

Fibrosis may refer to the deposition of connective tissue that occurs as a normal part of the healing process or the deposition of excess tissue that occurs as part of a pathological process.

If the fibrosis results from a response to injury, it is called scarring.

The term fibroma refers to fibrosis that arises from a single cell line.

Fibromas are benign tumors that can form in any part of the body.

In the pathological accumulation of extracellular matrix (ECM) proteins, fibrosis interferes with organ function.

Similar to an exaggerated wound healing response, fibrosis results in scarring and thickening of affected tissue. 

Many diseases end with fibrosis in various organs such as the lungs or liver.