Fibrosis is the formation of excess fibrous connective tissue in an organ or tissue in a reparative or reactive process.

This can be a reactive, benign, or pathological state. In response to injury, this is called scarring, and if fibrosis arises from a single cell line, this is called a fibroma.

Fibrosis occurs when excessive scar tissue builds up faster than it can be broken down and removed from the liver.