Is acanthosis nigricans an endocrine disorder?

No. Acanthosis nigricans is a dark skin discoloration, often found on the back of the neck and other skin folds. It is not an endocrine disorder, but is often present in people with endocrine disorders like pcos and type 2 diabetes. Pregnancy and some birth control pills can cause it too.
Acanthodians. Acanthosis is a skin disorder often caused by an endocrine disorder called Insulin resistance.