ICD-10 Code L59.0 – Erythema ab igne [dermatitis ab igne] (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code L59.0 – Erythema ab igne [dermatitis ab igne]
What it is
Erythema ab igne is a skin change caused by repeated exposure to heat, usually from a localized source. It often appears as a mottled, netlike discoloration rather than an acute burn.
Clinical signs
Typical findings include reticulated red-brown or hyperpigmented patches on skin exposed to chronic heat. Clinical features vary; refer to documentation.
When to use this code
Use L59.0 when the record clearly documents erythema ab igne or dermatitis ab igne due to repeated heat exposure. It may apply when the provider identifies a characteristic patterned rash linked to heating pads, space heaters, or similar sources. Check documentation if the cause is not explicit.
Do not use for
Do not use this code for acute thermal burns, contact dermatitis, or unexplained skin discoloration without documented heat exposure. Check documentation.
Coding tip
Confirm the note links the skin findings to chronic heat exposure before assigning L59.0.