Final answer:
Untreated actinic keratosis can develop into basal cell carcinoma (BCC) or melanoma.
Step-by-step explanation:
If actinic keratosis is left untreated, it can develop into basal cell carcinoma (BCC) or melanoma. BCC is a form of skin cancer that affects the mitotically active stem cells in the stratum basale of the epidermis, while melanoma is characterized by the uncontrolled growth of melanocytes, the pigment-producing cells in the epidermis. Both BCC and melanoma can be serious and require treatment, so it is important to have actinic keratosis examined and treated by a dermatologist if necessary.