Final answer:
Erythema is redness of the skin due to capillary dilation, often indicating inflammation.
Step-by-step explanation:
Erythema is the medical term used to describe redness of the skin due to capillary dilation. This condition is often a sign of inflammation or infection and is one of the five cardinal signs of inflammation, which also include edema, heat, pain, and altered function. Erythema can be a response to various factors, including localized injury, allergic reactions, or infections such as cellulitis and erysipelas.
One specific type called erythema nodosum is characterized by inflammation in the subcutaneous fat cells of the hypodermis, which results in red, tender nodules, typically on the legs or face. Common causes for erythema nodosum include infections like those from Streptococcus pyogenes, though it may arise from other pathogens as well.
The process of erythema involves increased blood flow to the affected area as part of the immune response, which helps bring white blood cells to fight off the causative agents of the disease.