Talk to Dermatologist on Dark Patches On Lips For 6 Years – Need Effective Treatment

Hello Doctor, I have had dark patches on my lips for approximately 6 years. My lips were normal before this problem started. Now, my lips have uneven pigmentation, with dark patches and light pink areas. The condition has remained almost unchanged for the past 6 years, and the patches are only on my lips, not on any other part of my body. I have consulted several doctors and tried different medications, but the problem has not resolved. Could you please help me identify the possible cause of these patches and recommend an appropriate treatment? I would also like to know whether any tests or examinations are needed and if there is a safe treatment to restore my natural lip colour. Thank you.