Snapshot A 60-year-old man with multiple "sun spots," or solar lentigos, comes to the dermatologist for his annual skin exam. He complains of several rough patches on his cheeks that has been there for a year. They feel like sandpaper. He is a gardener and often spent hours under the sun. AK close up Introduction Keratotic, pre-malignant lesions Epidemiology common in fair-skinned individuals common in elderly patients results from significant lifetime sun exposure keratinocyte damage May lead to squamous cell carcinoma Presentation Symptoms typically asymptomatic Physical exam thin, adherent scale that is transparent or yellow rough, “sand-paper” texture may see some telangiectasias frequently on sun-exposed areas face, head, neck, dorsal hands, ears Evaluation Skin biopsy dysplastic epidermis with keratinocyte atypia no invasion into dermis Differential Squamous cell carcinoma Actinic cheilitis Lentigo maligna Photoaging presents as rough texture, abundant wrinkles, and diffuse mottled pigmentation seen on histology as flattening of dermal papillae with basophilic depositions. Treatment Lifestyle modification avoid sun exposure use sunscreen Surgical liquid nitrogen (cryotherapy) = most common treatment Pharmacological topical 5-fluorouracil Prognosis, Prevention, and Complications Prognosis typically slow-growing and persistent if untreated Prevention avoid sun exposure use sunscreen Complications risk of progression to squamous cell carcinoma