Talk to Dermatologist on Tanning On Neck /black Neck

"I have noticed that the skin on my neck has become significantly darker compared to the rest of my body. This discoloration resembles a tanned or blackened patch, and it doesn't seem to be improving. It’s not just sun exposure; the darkening persists even in areas not directly exposed to sunlight. I would like to understand what could be causing this darkening, whether it could be related to skin conditions like acanthosis nigricans, hyperpigmentation, or another health issue, and what treatment options are available."