What is acanthosis nigricans?

black line around your neck
on Thu 21 Nov


If you have noticed a thick brown/black line around the back and sides of your neck – or on the neck of someone else – your initial thought may be that it’s been caused by a necklace that needs cleaning. 


However, you could be looking at a condition called acanthosis nigricans.


This condition does not only appear around the neck but most typically also in the skin folds of your armpit or groin. Less often it can also occur on the back of the knees, the front of your elbows, on your palms /soles or under the breasts.


The black patches cannot be rubbed off and are dry and “velvety” to the touch.  The skin tends to thicken and occasionally the area is itchy and/or additionally has skin tags.


The medical terms for skin becoming darker in this way is “hyperpigmentation” and the term for the skin becoming thicker is “hyperkeratosis”


The causes of acanthosis nigricans

Typically appearing in people below the age of 40, acanthus nigricans is very common in conditions connected with hormonal changes associated with insulin resistance such as



Insulin resistance  is associated with central fat distribution – the so called “apple shape” – which is an indicator for an increased risk of type 2 diabetes. Please read this post on the subject  


Corticosteroids are also associated with the condition.


Rarely it can be associated with cancer – usually of the stomach. The latter form is called “malignant acanthosis nigricans” and tends to develop in middle aged people who are not obese.  In this case the patches develop abruptly.


What actually triggers acanthosis nigricans?

Where the condition is in existence there would appear to be a much higher presence of fibroblasts – a connective tissue cell which produces collagen – and a greater than usual stimulation of skin cells that produce keratin.


This is likely to be caused by high levels of insulin or an insulin like growth factor which is encouraging the over propagation of these skin cells


There is a very detailed explanation of the condition just here


How is acanthosis nigricans treated?

The main aim is firstly to diagnose the primary cause of the condition


  • Those who have it and are simply overweight will be encouraged into a more healthy lifestyle through diet and exercise
  • Those with hormone conditions or insulin resistance may find the condition improves as their own health is stabilised through medication
  • If the condition has been triggered by medication itself this will have to stop
  • If the condition is malignant the underlying tumour will require treatment


There are topical creams associated with lightening age spots that can improve the cosmetic appearance.  Some people may feel they need to look at laser therapy or dermabrasion.


I hope this has been helpful.


Although every effort is made to ensure that all health advice on this website is accurate and up to date it is for information purposes and should not replace a visit to your doctor or health care professional.


As the advice is general in nature rather than specific to individuals Dr Vanderpump cannot accept any liability for actions arising from its use nor can he be held responsible for the content of any pages referenced by an external link


acanthosis nigricans Acromegaly Addison's disease adolescent diabetes problems adolescent thyroid problems Adrenal crisis adrenal fatigue Adrenal glands Anovulation artificial pancreas Autoimmune Thyroiditis Bariatric Surgery blood glucose levels blood pressure breastfeeding CAH Charcot foot cholesterol CHT coffee cold and flu medications Conception Congenital adrenal hyperplasia congenital hypothyroidism Consultant Endocrinologist London coronavirus cortisol covid-19 Cushing's disease Cushing's syndrome Depression Diabetes diabetes and bone health diabetes and heart health diabetes and oral health diabetes and parkinsons diabetes and sexual dysfunction diabetes and skin conditions diabetes and thrush diabetes in China diabetes insipidus diabetes latest diabetic ketoacidosis diabetic neuropathy Diabetic prevalence diabetic retinopathy diet for diabetes diet for obesity Disability Act Down's Syndrome Dr Mark Vanderpump e-consulting endocrine system fertility folic acid Freestyle Libre frozen shoulder and thyroid Fruit sugars gestational diabetes Gigantism Glucose Monitoring Glucose Tolerance Test gluten free Goitre Graves Disease Graves Orbitopathy guthrie test hair loss Hashimoto's Disease healthcare services hearing loss Heart Disease heel prick test Hepatitis C Hormones - most important how to lose weight hyperparathyroidism Hypersecretion Hyperthyroidism hyperthyroidism and respiratory problems Hypocalcaemia Hypogonadism hypoparathyroidism hypophysitis Hyposecretion Hypothyroidism hypothyroidism and respiratory problems IFG IGT immunotherapy side effects Impaired Fasting Glucose Impaired Glucose Tolerance Insulin Resistance Iodine IR iron Labour and birth late onset hypogonadism Levothyroxine Long Covid losing weight Low testosterone Mark Vanderpump MEN1 MEN2 menopause metabolic syndrome mood changes morning sickness Multiple endocrine neoplasia neuroendocrine tumour neuropathy Obesity obstructive sleep apnoea older patients online doctor OSA Osteoporosis overactive thyroid ozempic Pancreas Pancreatic Cancer Pancreatic Diabetes parathyroid glands Patient Resources Patient Support Groups PCOS PCOS and acne PCOS and fertility PCOS and Insulin PCOS diet Phaeochromocytomas Pituitary Gland POF Polycystic Ovary Syndrome Post menopause thyroid problem Post pregnancy thyroid problem postnatal diabetes medication postnatal thyroid medication Prader-Willi Syndrome pre-eclampsia prediabetes pregnancy Pregnancy and Diabetes Pregnancy and Thyroid Disease Premature Ovarian Failure prolactinomas PTH puberty Radioactive Iodine RAI resistant hypertension semaglutide Sheehan's Syndrome Skin tags sleep and diabetes sleep and obesity soy Soya steroid dependent subacute thyroiditis T4 Tara Palmer Tomkinson testosterone Tetany The endocrine system Thyroid thyroid and menstruation thyroid cancer Thyroid disease in children thyroid nodules Thyroid Storm thyroid tests Thyroiditis Thyrotoxic Periodic Paralysis Thyroxine TSH levels TSH Testing tumours Type 1 diabetes Type 2 Diabetes Type 3 diabetes underactive thyroid Vitamin B complex Vitamin D Waist circumference weight gain weightloss

Please get in touch

Phone: 07565 978310

Contact form