Have you noticed hyperpigmentation on your neck? Well, a few things could be causing it. The skin on your neck is thinner than the rest.So, it could just be the result of UV radiation sensitivity (sun), or you could have natural hyperpigmentation on the neck. But, if you’ve noticed a marked difference or patches, it may not be hyperpigmentation. There is a condition called acanthosis nigricans, and it might be worth checking in with your doctor or reading about it. 

Acanthosis nigricans (NY-gruh-kans)

“Acanthosis nigricans is a condition that causes areas of dark, thick velvety skin in body folds and creases. It typically affects the armpits, groin, and neck.”

 

Photo cred: NHS

Why does acanthosis nigricans happen?

The direct cause of acanthosis nigricans has not been determined for sure, but scientists believe it results from high levels of insulin in the blood and hyperkeratosis. In many patients with acanthosis nigricans, abnormal concentrations of IGF-1 (insulin growth factor) are seen. 

Insulin is a hormone that regulates blood sugar levels.  Both high and low levels of IGF-1 activity are associated with having too much insulin, and it varies from patient to patient. But, specifically with acanthosis nigricans, patients often have high levels of IGF-1 activity. 

IGF-1 is a hormone and chemical messenger that promotes the growth of tissues, and it can help stimulate the proliferation of keratinocytes (a type of skin cell). And due to high insulin levels in the blood, scientists posit that hyperkeratosis is occurring in patients with acanthosis nigricans. 

Hyperkeratosis  is the thickening of the skin’s top layer, and it is associated with an abnormal quantity of keratin production. Likewise,  the discoloration is actually due to the thickness of keratin on the skin’s top layer, not increased pigment production.

Summary: High insulin levels can be related to more cell production than normal. So, these elevated insulin levels may be present in patients with acanthosis nigricans, a condition where there is an elevated amount of skin cell production. 

Genetics

Fibroblast growth factors can have defects or mutations at birth, and this can be related to acanthosis nigricans. Fibroblasts secrete keratin growth factors. Thyroid disorders and autoimmune disorders have also been linked to acanthosis nigricans. Mutations in the insulin receptor gene may also lead to acanthosis nigricans. 

Summary: Some people are born with defects in how their skin functions or with genes that have to do with insulin, and this may lead to acanthosis nigricans too.

AN and high insulin cont’d: What causes high insulin in the blood?

Type 2 diabetes 

The most common cause of acanthosis nigricans is type 2 diabetes and an excess of adipose tissue. With type 2 diabetes, the cells aren’t taking in sugar like they should. This is called insulin resistance. Insulin helps the glucose (blood sugar) get into your cells to give them energy.

When the body can't process glucose properly, it produces more insulin to compensate. This leads to high levels of insulin and glucose in the body because not enough is going into your cells, and as mentioned before, too much insulin can be related to too much keratin (in layman’s terms). 

PCOS

The HAIR-AN syndrome (Hyperandrogenemia, Insulin Resistance) has been described as another reason for acanthosis nigricans. HAIR-AN is associated with mutations in the insulin receptor gene, and patients have significantly higher levels of insulin and androgens like testosterone and androstenedione. 

High insulin levels directly stimulate androgen production in the ovaries, (additionally and potentially) leading to unusual hair growth (hirsutism), acne, and an increase in weight.

Conversely, high insulin levels as seen in high BMI or diabetic patients can react with insulin-like growth factors, leading to increased ovarian androgen production.

More simply, excess weight can cause high insulin, and this high insulin can make the ovaries produce more androgens, a sex hormone that can effect the hair and skin.

Things potentially related to acanthosis nigricans: 

GI complications

Some clinicians contend that “imbalances in the gut and a leaky gut lining (read more here) can lead to more inflammation and likewise, impaired insulin receptor function." So, basically, they’re saying that inflammation can affect the way the body responds to insulin. 

Stress 

Stress and elevated cortisol levels are other major but often overlooked factors, says functional medicine practitioner, Steve Grant. Stress acts as a stimulator of glucose, but it may also induce insulin resistance as well. 

Potential treatments for acanthosis nigricans:

Retinoids

Scrubbing will not resolve acanthosis nigricans, and any type of abrasion can damage the skin.

Topical retinoids are considered one of the first-line treatment options for AN, and they’ll typically prescribe tretinoin. Retinoids bind to RnR and RxR receptors in the skin to promote and thicken the lower layers of the skin so flakey or old skin cells can be pushed off, revealing a new layer of skin. This can help reduce the thickness and discoloration of acanthosis nigricans. Lasers have also been used in the treatment of acanthosis nigricans. 

The Ordinary Retinal 0.2% Emulsion Serum - $14.90

This is an OTC retinal. Retinal is typically more potent than retinol.

 

Medik8 Crystal Retinal 1 - $53

This is a high strength retinal. If you want to work up to tretinoin or if you can't get a tretinoin prescription, you can use retinal. 

 

Dermatica custom blended formulas

If you want tretinoin, online pharmacies can actually pair you with experts. Two of Cassandra's absolute favorites platforms are Dermatica, Agency, and Apostrophe.

Regimen for lowering BMI

Reducing BMI can help with insulin resistance and likewise acanthosis nigricans. Excess adipose tissue can impair cells’ normal response to insulin. 

Treating underlying causes

Some say prolonged use of oral contraceptives can increase the likelihood. Plus, if there is an underlying cause like PCOS, thyroid dysfunction, or an autoimmune disorder, speak with your doctor about a customized treatment plan.

 

Cover photo cred: istock images

 

Sources: 

https://health.clevelandclinic.org/the-best-skin-care-ingredients-for-your-neck

https://www.ncbi.nlm.nih.gov/books/NBK431057/#:~:text=In%20patients%20with%20benign%20acanthosis,(epidermal%20growth%20factor%20receptor).

https://pmc.ncbi.nlm.nih.gov/articles/PMC3308317/#:~:text=IGF%2DI%20has%20an%20almost,risk%20of%20type%202%20diabetes

https://medlineplus.gov/lab-tests/igf-1-insulin-like-growth-factor-1-test/

https://www.sciencedirect.com/topics/medicine-and-dentistry/acanthosis-nigricans

https://pmc.ncbi.nlm.nih.gov/articles/PMC7167451/

https://www.stevegranthealth.com/health-score/female-androgen-dominance/#:~:text=Excessive%20exercise%20without%20adequate%20recovery,a%20lowering%20of%20estrogen%20levels.

https://jamanetwork.com/journals/jamadermatology/article-abstract/535309#:~:text=%E2%80%94%20Prolonged%20use%20of%20oral%20contraceptive,of%20having%20malignant%20acanthosis%20nigricans.