1. Epithelial dysplasia → SCCIS → SCC
PRECANCEROUS LESİONS
Epithelial dysplasia → SCCIS → SCC

2. UVR
HPV
Ionizing radiation (chronic radiation dermatitis)
Chronic cicatrix
Thermal keratoses
Chronic inflammation
Non-healing wounds
Hydrocarbons (tar)
Chronic ingestion of inorganic arsenic
Immunosuppression ( drugs, HIV, organ transplantation)

3. ACTINIC KERATOSİS
Single or multiple, discrete, dry, rough, adherent scaly lesions occur on the habitually sun-exposed skin of adults, usually on a background of dermatoheliosis

4. Epidemiology and History
Age of onset: Middle age
Sex: More common in males
Race: SPT I,II, and III; rare in SPT IV; almost never in blacks or South Indians
Occupation: Outdoor workers ( especially farmers, ranchers, sailors) and outdoor sportspersons (tennis, golf, mountain climbing, deep-sea fishing)
Duration of lesions: Months to years.

5. Skin lesions and Distribution
Skin-coloured, yellow-brown, or brown (pigmented AK), often with a reddish tinge. Adherent, hyperkeratotic scale. Rough, “better felt than seen”!, oval or round.
Isolated single lesion or scattered discrete lesions. Face, ears, neck (sides), forearms, hands (dorsa), shins, scalp in bald males.

6. Differential Diagnosis, Course and Prognosis
Chronic cutaneous lupus erythematosus, irritated seborrheic keratosis, warts, SCC, superficial BCC, lentigo maligna.
May dissapear spontaneously, but in general remain for years. 2-5 % will develop into SCC.

7. Management Prevention!: UVB/UVA sunscreens Topical therapy Cryosurgery
Curettage ± electrosurgery
5-FU cream
Imiquimod
Retinoids
Facial Peels
Dermabrasion
Laser surgery: Erbium or C02
Photodynamic Therapy
Systemic therapy: Acitretin or isotretinoin