An auto-injector device including a syringe, a needle arranged in the vicinity of a first end of the syringe, and a plunger arranged within the syringe. A volume within the syringe between the plunger the needle accommodates medicine, such that movement of the plunger toward the needle dispenses medicine through the needle. A selection assembly configurable by a user to adjust an amount of medicine dispensed by the auto-injector device and depth to which the medicine is delivered. Also, a method for treating a skin lesion or skin disorder utilizing the auto-injector and a kit for patient administered treatment.