Reddening of the skin in patches is known as erythema in medical terms. This is due to capillary congestion. It can occur in various skin conditions like allergic skin reaction, side effects of skin treatments, insect sting, sunburn, thermal injuries, infection, etc.
Understanding Figurate Erythemas
Figurate erythemas are a group of skin conditions characterized by ring-shaped, arciform, or polycyclic lesions often associated with systemic diseases.