Solar keratoses are a reflection of abnormal skin cell development due to exposure to ultraviolet radiation. They are considered pre-cancerous or an early form of squamous cell carcinoma.
They appear as multiple flat or thickened, scaly or warty, skin coloured or reddened lesions. A keratosis may develop into a cutaneous horn.
Solar keratoses are very common 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. On the lips they are often called actinic or solar cheilitis. They are especially common in fair-skinned persons or those who have worked outdoors for long periods without skin protection. Sun-damaged skin is also dry, discoloured and wrinkled.