Regression (medicine)

Regression in medicine is the partial or complete reversal of a disease's signs and symptoms.

• Clinically, regression generally refers to a decrease in severity of symptoms without completely disappearing. At a later point, symptoms may return. These symptoms are then called recidive.

• In cancer, regression refers to a specific decrease in the size or extent of a tumour.^[2] In histopathology, histological regression is one or more areas within a tumor in which neoplastic cells have disappeared or decreased in number.^[3] In melanomas, this means complete or partial disappearance from areas of the dermis (and occasionally from the epidermis), which have been replaced by fibrosis, accompanied by melanophages, new blood vessels, and a variable degree of inflammation.^[3]