The pathogenesis of a disease is the mechanism by which the disease is caused. The term can also be used to describe the origin and development of the disease and whether it is acute, chronic or recurrent. The word comes from the Greek pathos, "disease", and genesis, "creation".
Types of pathogenesis include microbial infection, inflammation, malignancy and tissue breakdown.
Most diseases are caused by multiple pathogenetical processes together. For example, certain cancers arise from dysfunction of the immune system (skin tumors and lymphoma after a renal transplant, which requires immunosuppression).
Often, a potential etiology is identified by epidemiological observations before a pathological link can be drawn between the cause and the disease.