Koebner phenomenon to heat in cutaneous (discoid) lupus erythematosus (lupus ab-igne).

A 63-year-old woman with a ten-year history of systemic lupus erythematosus presented with a three-year history of a large, pruritic lesion that was located on the back and a pruritic lesion that was located on the right thumb. She was a baker by profession for many years during which time she often stood with her back to a hot oven. Physical examination of the lower back showed a large, atrophic, and reticulated plaque with a hyperpigmented border. On the right thumb was a well-demarcated, erythematous plaque with adjacent loss of the medial nail plate on the affected finger. Histopathology of both skin lesions showed cutaneous lupus erythematosus. This patient displays the Koebner phenomenon to heat in cutaneous (discoid) lupus erythematosus. We propose the term lupus ab-igne to describe her skin lesions. There are a few reports of the Koebner phenomenon occurring in patients with lupus erythematosus in response to contact dermatitis, tattoos, zoster, operative scars, scratching, or pressure from clothing. To our knowledge, this is the first report of heat as the physical factor leading to the formation of cutaneous lupus lesions.