### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
My son is 15 years old, he has been getting dark skin behind his neck and behind his ears.  It looks like he has not washed his neck in weeks.  It is not itchy.  Now he has two round spots on either shoulder.  I have put on lotion with vitamin e for 3 days twice a day and 90 % is gone...but it will come back if I do not put lotion on for awhile...it looks horrible ..what is causing this?

### output:

Hello and welcome to Chat Doctor I would keep a possibility of Pseudoacanthosis Nigerians as the reason for the dark patches around the neckPseudoacanthosis Nigerians is a skin disorder in which there is darker, thick, velvety skin in body folds and creases. The skin becomes dark, velvety and thick in areas such as back and sides of neck, armpits, thighs, elbows and knees. Acanthosis Nigerians usually appears slowly and doesn't cause any symptoms other than skin changes. It typically occurs in individuals younger than age 40, may be genetically inherited, and is associated with obesity OR endocrinopathies, such as hypothyroidism, acromial, polycystic ovary disease, insulin-resistant diabetes, or Bushings disease. The majority of cases of acanthuses Nigerians are associated with obesity OR are otherwise idiopathic. This is likely because of insulin resistance, and more likely to occur in darker-skinned persons. This is also known as Pseudo-Acanthosis Nigerians. Acanthosis Nigerians is likely to improve in circumstances where a known cause is removed. For example, obesity-related acanthuses Nigerians will improve with weight loss. People with acanthuses Nigerians in general should be screened for diabetes. Weight loss and controlling blood glucose levels through exercise and diet often improves symptoms. Topical retinoid 0.05% cream once daily at night helps to lighten pigmentation along with weight loss, exercise and diet management. Alpha-Lipoic acid ha been shown to increase insulin sensitivity and thereby reverses the pseudo-acanthosis Nigerians which arises as a result of insulin resistance states e.g. Obesity and diabetes. It is commercially available for prescription in acanthuses Nigerians. Regards