Treatment of Erythema Ab Igne

The primary and most critical treatment for erythema ab igne is immediate and complete cessation of heat exposure to the affected area. 1, 2, 3

First-Line Management: Heat Source Removal

Immediately discontinue all contact with the causative heat source (heating pads, space heaters, laptop computers, hot water bottles, heated car seats, or any infrared radiation source). 1, 2
Counsel patients extensively on the importance of permanently stopping prolonged heat exposure, as this is the only effective measure to prevent progression. 2
Early removal of the heat source typically results in progressive clearing over 8 weeks, though complete remission may not occur. 2
Delayed diagnosis and continued heat exposure can result in permanent hyperpigmentation or malignant transformation to squamous cell carcinoma, Merkel cell carcinoma, or basal cell carcinoma. 1, 3, 4

With prompt heat source removal, prognosis is good and complete remission is possible in early cases. 3
In two-thirds of cases, skin changes progressively clear but may not completely resolve. 2
Patients who continue heat exposure will have persistent skin changes that may become permanent. 2
Chronic cases with established cutaneous atrophy and hyperpigmentation may never fully resolve even after heat source removal. 3

For patients with chronic erythema ab igne showing epithelial dysplasia or carcinoma in situ, additional topical treatments are necessary:

Topical 5-fluorouracil cream has shown good response in individual case reports of established epithelial dysplasia. 5, 3
Topical imiquimod is an alternative option for premalignant changes. 5
Photodynamic therapy has achieved successful results in cases with carcinoma in situ. 5
Topical retinoids may be considered for chronic cases with premalignant cutaneous dysplasia. 3
Laser treatments are an option for persistent pigmentary changes. 3

All patients with permanent skin changes require ongoing monitoring due to the accepted precancerous nature of chronic erythema ab igne. 2, 4
Biopsy is indicated when malignancy is suspected, particularly if there are histologic features of squamous atypia with basal layer crowding and loss of maturation throughout the epidermis. 1, 4
Watch specifically for development of squamous cell carcinoma, Merkel cell carcinoma, or cutaneous marginal zone B cell lymphoma in longstanding cases. 3, 4

Do not delay counseling about heat source removal—this is the definitive treatment and delays result in permanent changes or malignancy. 1, 2
Do not assume patients will spontaneously stop the causative behavior; patients with eating disorders (a common population affected) may have increased pain thresholds and continue heat exposure despite skin changes. 2
Do not dismiss localized erythema ab igne over areas of pain (abdomen, lower back) as purely cosmetic—this can indicate underlying disorders including cancer. 3
Do not provide false reassurance about complete resolution—inform patients that chronic cases may result in permanent pigmentation. 2, 3