This is a transient, reticulated, vascular pattern that appears on exposure to cold and disappears with rewarming, unlike the fixed, hyperpigmented pattern of erythema ab igne.
This is a congenital condition, present from birth, and consists of a persistent, blue-violet reticulated pattern, unlike the acquired, heat-induced pigmentation of erythema ab igne.
While also a reticulated vascular pattern, livedo reticularis is often associated with systemic diseases (like vasculitis) and represents a physiological response, whereas erythema ab igne is a direct thermal injury to the skin.
Poikiloderma is a combination of atrophy, telangiectasias, and mottled hyper- and hypopigmentation, a more complex pattern than the net-like hyperpigmentation of erythema ab igne.
