rubor

Rubor is the Latin term for redness and is used in medical contexts to describe the reddish discoloration of tissue caused by increased blood flow during inflammation. It is one of the classic signs of inflammation described in antiquity, alongside calor (warmth), tumor (swelling), and dolor (pain); functio laesa (loss of function) was later added by Rudolf Virchow. The word rubric is often encountered in clinical notes and pathology to indicate vascular changes rather than a specific disease.

Pathophysiology: In acute inflammation, rubor results mainly from arteriolar vasodilation and increased capillary blood flow in the affected area. This response is mediated by chemical mediators such as histamine, nitric oxide, prostaglandins, and bradykinin. The increased blood volume in the tissue produces the visible redness and the accompanying warmth (calor). Enhanced vascular permeability may also occur, contributing to edema (tumor).

Clinical context and assessment: Rubor can appear in infections, injuries, dermatitis, sunburn, and various inflammatory or immune reactions. It may also occur as a physiological flush in response to heat or emotion. Clinicians assess the extent and distribution of rubor and its association with pain, swelling, or heat. The appearance can be less conspicuous in individuals with darker skin tones, and documentation may use imaging or thermographic methods in research or complex cases.

Differential and interpretation: Rubor indicates increased blood flow but does not specify the cause. It should be interpreted together with other signs (calor, tumor, dolor, and functional loss) and clinical context to distinguish infection, trauma, vasculitis, or other vascular conditions from benign flushes.