Number of treatments: Multiple treatments are required to avoid repigmentation of nearby unirradiated melanocytes. Age of treatment: Patients who develop the disease before the age of one and those who are actively treated before the age of five generally have good results, but some patients who are younger are more likely to relapse, probably because melanocytes are more actively growing in younger patients. Efficacy: There is no laser that can achieve completely ideal results. The recurrence rate is high. After several treatments, some patients can achieve a satisfactory outcome, but a small number of patients can relapse quickly, so the outcome is sometimes unpredictable.