Laptop-induced erythema ab igne

A 21‐year‐old man presented with a 2‐month history of an asymptomatic patch on the left thigh. On physical examination, a reticulated, dark reddish‐brown pigmented patch with an undefined border was seen on the left thigh (Fig. 1). The patient reported to prolonged contact with any heat sources reported in the literature, except that in order to complete a project, he had used his laptop computer intensely for 3 months preceding the occurrence of the lesions, and while working on this computer, he often placed it on his anterior thighs. Reticulated, dark reddish‐brown pigmented patch with an undefined border seen on the left thigh of the patient. Histological examination of a biopsy taken from the lesion showed orthohyperkeratosis, abundant dyskeratotic cells and hydropic degeneration in the basal cell layer in the epidermis. Some keratinocytes displayed atypical changes, such as enlargement of the nucleus, pleomorphism and prominent nucleoli (Fig. 2). There was mild fibroblastic activity and scattered pigment‐laden macrophages in the upper dermis. Using orcein stain, there was no change seen in the elastic fibres. Based on the clinical and histological features, a diagnosis of erythema ab igne was made. Atypical keratinocytes with many dyskeratotic cells within the epidermis, and focal areas of hydropic degeneration in the basal cell layer (haematoxylin and eosin, original magnification × 200). Erythema ab igne is characterized by chronic reticulated telangiectases and pigmentation, caused by chronic exposure to infrared radiation. It is typically seen on the frontal thighs and shins of women who habitually sit in front of or near a heat source.1 There have only been five cases of laptop‐induced erythema ab igne reported previously in the literature. All cases were induced by infrared heat radiating from the optical drives of the laptops.2–5 The typical feature of laptop‐induced erythema ab igne is the involvement of only one side of the leg, as in our case and in the other cases reported, which corresponds to the location of the optical drive. As the optical drive of our patient’s laptop was located on the left, the lesions occurred on his left thigh. Erythema ab igne is accepted as a precancerous lesion.1 Squamous cell carcinoma and Merkel cell carcinoma can develop on such lesions.5 There is no effective treatment. The progression of the disease can only be prevented by removal of heat exposure.1 These cases emphasize that the use of laptop can induce a precancerous lesion, erythema ab igne. Patients with the condition should be questioned about any history of intense laptop use. In addition, all laptop users should be warned to avoid placing laptops on their thighs for prolonged periods. Conflict of interest: none declared.