In the simplest terms, pathogenesis describes how a disease begins and develops. In medical studies, researchers may discuss pathogenesis in a tangential sense, such as noting that the pathogenesis of a disease has yet to be understood, or in exploring possible biological mechanisms (including exposures in observational studies) that might explain how something might cause a particular disease.
If you’re new to reporting on a specific condition, it can be especially helpful to look in PubMed for studies that specifically focus on the pathogenesis of that condition. Not only will such papers discuss risk factors and (any known) causes of the disease, but they will help you understand why and how those factors and causes contribute to the disease. Although pathogenesis is closely related to a disease’s etiology, there’s a subtle difference between the concepts. The etiology is the specific origin of a disease while pathogenesis is the full process of development, focusing more on the biological mechanism and how the disease proceeds.