Actinic keratoses is represented by scaly papules which occur on exposed skin of older, fairer-skinned, persons resulting from chronic overexposure to ultraviolet light from the sun. Actinic keratoses are mostly found on sites repeatedly exposed to the sun especially the backs of the hands and the face, most often affecting the nose, cheeks, upper lip, temples and forehead. They are especially common in fair-skinned persons or those who have worked outdoors for long periods. A small percentage of these lesions do develop into invasive squamous cell carcinoma. As a result of the potential for actinic keratoses to continue to evolve to in situ and then invasive squamous cell carcinoma, a rarely reported but often misdiagnosed variant of the classic actinic keratoses known as spreading pigmented actinic keratosis has earned itself attention in the scholarly literature (Uhlenhake, Omar, Sangueza, Lee & Jorizzo, 2010). In a recent study, researchers from the Wake Forest University School of Medicine, sought to review current data and identify areas needing further research to establish diagnostic guidelines for spreading pigmented actinic keratosis and to increase awareness of this common entity (Uhlenhake, Omar, Sangueza, Lee & Jorizzo, 2010). In this study it was found that spreading pigmented actinic keratoses is a rarely reported lesion that can be difficult to distinguish from other benign and malignant pigmented lesions, including seborrheic keratosis, melanoma in situ and lentigo maligna melanoma. Located mainly on sun-exposed areas and with a size gretaer than 1.4 cm, the lesion typically spreads laterally. Pathologically, it was found that the lesion resembles classic actinic keratoses with increased basal melanisation ( Uhlenhake, Omar, Sangueza, Lee & Jorizzo, 2010).
Uhlenhake, E.E., Omar, B.S. Sangueza, P., Lee, A.D. & Jorizzo, J.L. 2010. Spreading pigmented actinic keratosis: a review. Journal of American Academic Dermatology, 63, 499-506.