Hello, Thank you for writing to us at healthcaremagic I would keep a possibility of acanthosis Nigricans as the reason for dark skin around the neck. The involved skin in acanthosis has darker, thick, velvety texture in body folds and creases. Acanthosis nigricans usually doesn t cause any symptoms other than the skin changes. The majority of cases of acanthosis nigricans are associated with obesity OR are otherwise idiopathic. This is likely because of insulin resistance, and is more likely to occur in darker-skinned persons. Acanthosis is also associated with various endocrinopathies, such as hypothyroidism, acromegaly, polycystic ovary disease, insulin-resistant diabetes, or Cushing s disease. People with acanthosis nigricans in general should be screened for insulin resistance and diabetes. Weight loss and controlling blood glucose levels through exercise and diet often improves the skin condition. Topical tretinoin 0.05% cream once daily at night helps to lighten pigmentation along with weight loss, exercise and diet management. Alpha-Lipoic acid has been shown to increase insulin sensitivity and thereby reverses the skin condition to an extent. regards