Poorly differentiated carcinoma arising in the setting of erythema ab igne.

Erythema ab igne (EAI) is a reticulated, erythematous, or hyperpigmented dermatosis that is caused by chronic exposure to infrared radiation. Chronic lesions of EAI have significant potential for malignant transformation. We report a case of poorly differentiated carcinoma arising within a patch of long-standing EAI on the lower extremity of a 92-year-old female. This case highlights the importance of recognizing EAI early and counseling patients to avoid further exposure to the offending infrared source to reduce the risk of malignant transformation. EAI has been associated with several different types of cutaneous neoplasms including the Merkel cell carcinoma, squamous cell carcinoma, and cutaneous marginal zone lymphoma.