Darkness around the neck is a common condition caused by hormones weight gain pregnancy insulin resistance and certain medical conditions. This condition called Acanthosis Nigricans is dark pigmentation along with velvety feel to the skin that can commonly be seen around the neck and other skin folds such as armpits and groin explains Dr Shuba Dharmana Dermatologist and Medical Director Lejeune Medspa Bangalore. She adds It can occur in any age group. Read: Dark patches on the neck could be the sign of these 3 skin problems Dr Shuba Dharmana lists out few causes: Certain medical conditions like Cushing's diseases