Acetamides/adverse effects; Keratosis, Actinic/drug therapy; Morpholines/adverse effects; Protein Kinase Inhibitors/adverse effects; Pyridines/adverse effects; Scalp Dermatoses/drug therapy; Secondary Prevention/methods; Acetamides/administration & dosage; Aged; Drug Administration Schedule; Erythema/chemically induced; Erythema/diagnosis; Erythema/epidemiology; Face; Female; Follow-Up Studies; Humans; Keratosis, Actinic/diagnosis; Male; Middle Aged; Morpholines/administration & dosage; Ointments; Pain/chemically induced; Pain/diagnosis; Pain/epidemiology; Proof of Concept Study; Protein Kinase Inhibitors/administration & dosage; Pruritus/chemically induced; Pruritus/diagnosis; Pruritus/epidemiology; Pyridines/administration & dosage; Recurrence; Scalp Dermatoses/diagnosis; Severity of Illness Index; Treatment Outcome