Kératoses actiniques : diagnostic anatomoclinique: Clinicopathologic diagnosis of actinic keratosis

Abstract

Actinic keratoses are epidermal preneoplastic lesions localised in photo-exposed areas. They are made of a keratosis of variable thickness overlying an erythematous area, that may be indurated. A field of cancerization is characterized by multiple actinic keratoses in a chronically sun exposed area, especially on the bald area of the scalp in aged males. In general, the diagnosis is made on clinical basis, but a biopsy is necessary in case of ulceration, induration, post-treatment recurrence or bleeding. Biopsy is also mandatory for atypical keratosis, especially the pigmented variants. Histopathology shows dysplasia of the epidermal basal layer, with irregular and hyperchromatic nuclei, parakeratosis and generally a dermal lymphocytic infiltrate. There are hypertrophic, atrophic, pigmented and lichenoid variants among the most common subtypes. The main clinicopathological issue is transformation of actinic keratosis into squamous cell carcinoma, defined by epidermal sheaths of atypical cells penetrating into the dermis. These cells are eosinophilic and show images of dyskeratosis or squamous whorls. Dermatoscopy (and other non invasive imaging techniques) might be useful to help decision making - when to perform a biopsy - and for differential diagnosis. © 2019 Elsevier Masson SAS. All rights reserved. Cet article fait partie du numéro supplément Kératoses actiniques : comprendre et traiter réalisé avec le soutien institutionnel de Galderma International.

Keywords: Actinic keratosis; Carcinome épidermoïde; Dermatopathologie; Dermatopathology; Dysplasie épidermique; Epidermal dysplasia; Kératose actinique; Squamous cell carcinoma.