Kératose lichénoïde striée et exposition prolongée aux infrarouges

Erythema Ab Igne with Histological Features of Keratosis Lichenoides Chronica

Erythema ab igne (EAI) is a localized, hyperpigmented and reticulated dermatosis at sites of chronic heat exposure. Within longstanding skin lesions of EAI, hyperkeratotic lesions may emerge and can potentially transform into pre-malignant or malignant skin lesions. A 55-year-old woman presented for the evaluation of multiple hyperkeratotic lesions along with a reticular patterned hyperpigmentation on her right knee, an area that had repeated and prolonged exposure to a heat source over a period of several months. Based on her clinical history and the physical examination of her lesions, she was diagnosed as having a hyperkeratotic form of EAI. A skin biopsy was performed to rule out malignant alteration, but the histopathological findings were supportive of keratosis lichenoides chronica.

Erythema ab igne with features resembling keratosis lichenoides chronica

Erythema ab igne (EAI) is an asymptomatic dermatosis that develops in response to chronic exposure to low-grade heat. Characteristic findings on histopathology include epidermal atrophy, dermal elastosis, atypical histiocytes, and melanin and hemosiderin deposition. Reactive endothelial changes and prominent vascular proliferation are variable. Keratosis lichenoides chronica (KLC) is a rare lichenoid hyperkeratotic dermatosis. Acanthosis with parakeratosis and a lichenoid interface dermatitis with lymphocytes, histiocytes, and plasma cells are characteristic findings of KLC. Although its etiology remains unclear, KLC has been reported to occur in response to heat. Herein, we report a case of EAI with features resembling KLC.

The other end of the rainbow: infrared and skin

Although infrared radiation (IRR) is ubiquitous in the terrestrial milieu, its effects on human skin have until now been largely ignored. Recent studies suggest an important role for infrared A (IRA) radiation (760-1440 nm) in dermal inflammation, photoaging, and photocarcinogenesis. In this issue, Calles et al. identify and analyze the IRA-induced transcriptome in human dermal fibroblasts. Their work paves the way for new research directions in IRA photobiology and raises important clinical questions regarding photoprotection and IRR-based dermatotherapy.

Keratosis Lichenoides Chronica: Proposal of a Concept

It has been a subject of controversy whether keratosis lichenoides chronica (KLC) is a distinctive inflammatory disease of the skin or whether it represents a manifestation of another well-known disease, such as lichen planus, lupus erythematosus, or lichen simplex chronicus. In search of clear criteria for diagnosis of KLC the entire literature pertinent to the subject was studied and findings clinical and histopathologic as they were telegraphed in them were compared with a patient of my own experience. Review of the literature reveals more than 60 patients in whom the diagnosis of KLC was made. Three categories emerge based on whether the findings presented in a particular article (1) do not permit any diagnosis to be rendered; (2) do allow a diagnosis specific to be made, such as of lichen simplex, lichen planus, or lupus erythematosus; or (3) do not correspond to any disease well defined, such as lichen simplex, lichen planus, lupus erythematosus, but seem to show attributes morphologic, clinically and histopathologically, that are repeatable. Patients diagnosed as having KLC obviously represent a potpourri of different diseases, the most common of them being lichen simplex chronicus, lichen planus, and lupus erythematosus. Fewer than 25 patients reported on, however, presented themselves with lesions very similar to one another clinically, namely, an eruption that involved the face in a manner reminiscent of seborrheic dermatitis and with tiny papules on the trunk and extremities, which assumed linear and reticulate shapes by way of confluence of lesions. Individual papules were infundibulocentric and acrosyringocentric. Findings histopathologic were those of a lichenoid interface dermatitis affiliated with numerous necrotic keratocytes and covered by parakeratosis housing neutrophils in staggered fashion. These patients seem to have an authentic and distinctive condition that is exceedingly rare. In conclusion, the diagnosis of KLC should be made only for patients who present themselves with features clinical and findings histopathologic that resemble closely those of what is summarized in this article under category 3.