Erythema Ab Igne
Erythema ab igne (EAI), sometimes called toasted skin syndrome, is a pigment and blood vessel change caused by long-term, repeated exposure of the skin to infrared heat below the level that causes a burn (usually 43–47°C). It shows up as a net-like (reticular) red pattern that gradually turns dark brown or gray-blue, sometimes with thinning of the skin, in areas that are regularly in contact with a heat source, such as the thighs from a laptop, the abdomen or back from a hot-water bottle, or the lower legs from a heater.
EAI begins as a harmless vascular and pigment reaction to chronic heat, but it reflects real damage to the dermis (heat-induced elastic fiber degeneration) along with hemosiderin deposits. If heat exposure continues for years without treatment, EAI can progress to precancerous lesions such as actinic keratosis or to squamous cell carcinoma (SCC).
At Haute-Derma, we treat toasted skin syndrome in three stages: removing the heat source, restoring the blood vessels and dermis, and clearing pigment with a 1064 nm picosecond laser. This rebuilds the skin safely and gives the best possible cosmetic result.
Pathogenesis and Cellular Mechanisms of Erythema Ab Igne
Toasted skin syndrome develops through a combination of heat-driven changes: blood vessel damage, hemosiderin buildup, and increased melanin production:
- Superficial vessel dilation and red cell leakage (erythrocyte extravasation): Repeated heat widens the network of superficial dermal capillaries. Rising pressure in these tiny vessels causes small breaks in their walls, and red blood cells leak into the surrounding tissue. As those cells break down they release iron as hemosiderin, which leaves a lasting gray-blue or gray-brown color in the dermis.
- Heat-induced elastic fiber damage (thermal elastosis): Much like UV damage (actinic elastosis), chronic infrared heat breaks down collagen bundles and alters the elastin fibers in the dermis. Fibroblasts work less well, so the affected skin slowly loses its elasticity and develops fine areas of atrophy.
- Melanocyte activation and increased eumelanin: Heat directly stimulates the pigment cells in the basal layer of the epidermis to make more melanin. Melanin in the epidermis combined with hemosiderin in the dermis produces a layered, net-like color ranging from light brown to brown-black.
Differential Diagnosis of Net-Like Pigment and Vascular Patterns
| Toasted Skin Syndrome (EAI) | Livedo Reticularis | Livedoid Vasculopathy |
|---|---|---|
| Damage from chronic infrared heat | Capillary spasm in the microcirculation, triggered by cold or autoimmune disease | Thrombotic occlusion of dermal vessels |
| History of heat exposure (laptop, heating pad) | Not related to heat (often triggered by cold) | Not related to temperature |
| Melanin (epidermis) plus hemosiderin (dermis) | No pigmented spots (only red-blue mottling from vessel dilation and spasm) | White scars (atrophie blanche) with a pigmented rim |
| Mild burning or no symptoms | Cold, numb fingers and toes | Marked stabbing pain; may ulcerate or become necrotic |
| Risk of malignant change (SCC) if long-standing | Associated with systemic disease (lupus, APS) | Chronic; leaves white atrophic scars |
Examination, Dermoscopy, and Medical Screening at Haute-Derma
- History of heat-producing devices: We pin down the heat source, such as a laptop resting on the thighs, a hot-water bottle for period pain or back pain, a heated pillow, or work near a furnace or oven.
- Detailed dermoscopy: A network of dilated red-brown vessel loops (telangiectasia) with irregular gray-brown pigment dots and streaks arranged in a net-like pattern.
- Screening for precancerous change: We examine the surface closely for thickened, rough, scaly patches or sores that will not heal, and biopsy them when needed to rule out squamous cell carcinoma (SCC).
Safe Management and Treatment at Haute-Derma
Our EAI protocol follows a complete sequence designed to restore the blood vessels and clear the mottled pigment:
- Remove the Heat Source and Calm the Vessels
- Stop all contact with the heat source that caused the damage.
- Apply topical ingredients that strengthen vessel walls and act as antioxidants: vitamin K1, tranexamic acid 5%, niacinamide, and rutin.
- Restore the Dermis and Basement Membrane: Mesotherapy micro-injections of polynucleotides (PDRN) with non-cross-linked hyaluronic acid to repair heat-damaged collagen and elastin and bring back the skin's elasticity.
- Clear Melanin and Hemosiderin With a 1064 nm Picosecond Laser
- We use a 1064 nm picosecond laser in low-fluence toning mode (spot size 7–8 mm, fluence 0.8–1.2 J/cm²).
- The photomechanical effect shatters hemosiderin particles in the dermis and melanin in the epidermis with almost no heat, so macrophages can clear them without re-triggering vessel dilation.
- Course: 4–6 sessions, 3–4 weeks apart.
