What is Acanthosis Nigricans?
Acanthosis nigricans is a condition that causes the skin to become dark and velvety. It usually appears in areas where skin folds over itself, like the back of the neck, underarms, and groin. The darkened skin, which often thickens, usually has blurry borders. While most often linked to diabetes and insulin resistance, acanthosis nigricans can sometimes indicate internal cancer. Other times, it is related to hormone disorders or specific medications like systemic glucocorticoids, which is a type of steroid, and birth control pills.
What Causes Acanthosis Nigricans?
Acanthosis nigricans, a skin condition that causes dark, thick, and often velvety patches of skin, can be triggered by various factors. Here’s how:
1. Too much insulin in your blood can activate receptors in your skin cells, leading to skin cell growth. There’s a specific type of receptor, IGF-1, that responds powerfully to high insulin levels. When active, it speeds up skin cell and fiber tissue growth.
2. Certain inherited variations can result in growth factor defects, which might lead to acanthosis nigricans.
3. If associated with cancer, it’s thought to be down to increased levels of a molecule called transforming growth factor (TGF), which causes damage to the skin.
Familial acanthosis nigricans is a type that may occur from birth or during childhood and is caused by a genetic mutation. This type is often due to an inherited trait that affects the fibroblast growth factor receptor 3 (FGFR3), a protein that regulates cell growth and division.
Another common type is obesity-associated acanthosis nigricans. It is often seen in overweight adults but can occur at any age. These cases are often associated with insulin resistance. The most effective treatment for it is a healthy diet, weight reduction, or medical treatments, which can result in the improvement or resolution of the skin condition.
Certain medications such as nicotinic acid, systemic glucocorticoids, diethylstilbestrol, contraceptive pill, growth hormone therapy, and injected insulin have been known to trigger acanthosis nigricans. Once the medication is stopped, the skin condition usually improves.
There’s also a type associated with endocrine dysfunction, which affects hormone production. This can be a slow-developing type of acanthosis nigricans, generally affecting a smaller area of the body and often seen in people who are overweight. Certain diseases such as polycystic ovarian syndrome (PCOS) are associated with insulin resistance and can cause acanthosis nigricans.
The variant known as acral acanthotic anomaly is typically found on elbows, knees, knuckles, and the tops of feet, particularly in people with dark skin.
Malignant acanthosis nigricans syndrome is associated with cancers related to the digestive and urinary systems. Certain cancers like lung cancer and lymphoma are rarely associated. This type of acanthosis nigricans often develops rapidly and may also be linked to skin tags and multiple seborrheic keratoses (skin growths).
Auto-immune acanthosis nigricans is associated with autoimmune disorders, where the immune system mistakenly attacks the body’s own tissues, such as SLE, Sjogren’s syndrome, and scleroderma.
Unilateral acanthosis nigricans, also known as nevoid acanthosis nigricans, is a very rare type that occurs on one side of the body and is visible from birth or appears in childhood or adulthood.
Risk Factors and Frequency for Acanthosis Nigricans
Acanthosis nigricans is a condition that usually develops in people under 40 years of age. It’s often linked to several conditions such as obesity, under-functioning thyroid (hypothyroidism), excessive growth hormone production (acromegaly), polycystic ovary disease, insulin-resistant diabetes, and Cushing and Addison diseases. Some less common conditions associated with acanthosis nigricans are rare diseases like pinealoma, Cushing disease, ovarian hyperthecosis, stromal luteoma, ovarian dermoid cysts, Prader-Willi syndrome, leprechaunism, lipoatrophic diabetes, pineal hyperplasia syndrome, and Alstrom syndrome.
In the United States, this condition is more prevalent in Native Americans, African Americans, and Hispanics compared to Whites or Asians.
Signs and Symptoms of Acanthosis Nigricans
Acanthosis nigricans is a skin condition that often presents as an area of skin that is dark and thick. It’s not usually painful, but the skin might feel velvety and be itchy, with hyperpigmented patches or plaques that can be felt. One-third of the time, these skin changes show up before any signs of cancer in cases of malignant acanthosis nigricans. Another third of cases show skin lesions at the same time as the cancer appears. For the remaining third of cases, skin symptoms are noticed after a cancer diagnosis.
About a third of patients with malignant acanthosis nigricans experience skin changes before any signs of cancer. Another third develop skin lesions at the same time as cancer appears, and for the rest, skin changes occur after a diagnosis of cancer. In cases of malignant acanthosis nigricans, skin changes can occur suddenly and often come with intense itching.
- The skin changes mostly happen in the skin folds, like the groin, underarm, or back of the neck.
- In children, the back of the neck is the most common site.
- It can rarely be found in the mucous linings like the nose, mouth, esophagus, or voice box.
- Women may develop lesions on the nipple.
- In very rare cases, it has been reported in the lining of the eye.
- There can be associated skin tags in the same area.
- Nail changes like nail thickening (hyperkeratosis) and white nails (leukonychia) may be present.
It’s important to note that without a medical examination, it’s not possible to tell if the condition is benign or malignant just by looking at the lesions.
Testing for Acanthosis Nigricans
Acanthosis nigricans is a skin condition that is usually identified by a doctor’s examination and then confirmed with a skin biopsy, which is where a small sample of skin is taken to be tested. Following this, additional tests like blood tests, an endoscopy (which is a procedure where a thin tube with a camera attached is used to examine inside the body), or X-rays might be needed to rule out conditions like diabetes or cancer.
The biopsy will show changes in the skin, such as thickening (hyperkeratosis), an influx of white blood cells (leukocyte infiltration), the outer layer of skin folding more than it should (epidermal folding), and an increase in pigment-producing cells (melanocyte proliferation).
The main goal is to make sure it’s not linked to cancer. However, most instances of this skin condition are tied to insulin resistance (where your body doesn’t respond properly to the insulin hormone) and/or obesity. As a result, your doctor may recommend getting screened for diabetes and monitoring the amount of sugar attached to your red blood cells (measuring glycosylated hemoglobin).
Treatment Options for Acanthosis Nigricans
Acanthosis nigricans is a skin condition that involves dark, velvety patches in body folds and creases. Currently, acanthosis nigricans itself cannot be directly treated and the treatment focuses on addressing the underlying conditions that cause it. The dark patches on your skin might fade over time if the root causes, such as insulin resistance, are successfully managed. You can control your blood sugar levels with regular exercise and a healthy diet, which often improves symptoms. Topical creams, designed to lighten skin, can also be used in milder cases.
If acanthosis nigricans is caused by a tumor, successful removal of the tumor may completely resolve it. The main goal of treatment is to manage the disease that is triggering the skin condition. For most patients, treatment is primarily pursued to improve appearance. Weight loss and managing insulin resistance can decrease the severity of the skin condition in some patients. Medications that help improve the body’s sensitivity to insulin, such as metformin and rosiglitazone, can be helpful in the treatment process.
If you are taking medications that might have triggered acanthosis nigricans, it’s advised to discontinue them. It’s also recommended to lower the lipid profile (a group of tests that are often ordered together to determine the risk of heart disease) which can be successful with a healthy diet and introducing dietary fish and niacin (a form of vitamin B).
Dermatologists may prescribe skin treatments that improve the texture and tone of the skin. These include ingredients that help exfoliate the skin, known as keratolytics, like topical retinoids and podophyllin, as well as topical vitamin D analogs like calcipotriol, which help reduce the rapid growth of skin cells. The effectiveness of these treatments can vary.
Other substances, such as the drug octreotide, have shown promise in improving the condition in patients with insulin resistance. Melatonin, a hormone that regulates sleep-wake cycles, can also improve skin symptoms in obese patients with acanthosis nigricans by improving inflammation and insulin sensitivity.
Cosmetic treatments, including laser therapy, dermabrasion (a skin-resurfacing procedure), and chemical peels, have been tried to manage the symptoms of acanthosis nigricans. For cases where the skin condition turns malignant or cancerous, surgical removal of the lesions is the main treatment option.
What else can Acanthosis Nigricans be?
These are some of the conditions that may look similar to each other and doctors need to consider when diagnosing skin conditions:
- Seborrhea (a skin condition that causes flaky scales to form on oily areas such as the scalp or inside the ear)
- Tinea (a fungal infection of the skin, often known as ringworm)
- Erythrasma (a type of skin infection caused by bacteria)
- Candidiasis (a fungal infection typically on the skin or mucous membranes caused by Candida)
- Pellagra (a disease that happens due to a lack of niacin, a form of vitamin B)
- Ichthyosis (a family of rare genetic skin disorders characterized by dry, thickened skin)
- Linear epidermal nevus (a type of birthmark that consists of skin patches)
- Granular parakeratosis (a rare skin disorder characterized by dark, rough patches)
- Cutaneous hyperpigmentation related to Addison disease (darkening of the skin that can happen in people with Addison disease, which is a disorder of the adrenal glands)
What to expect with Acanthosis Nigricans
People with the benign, or non-harmful, form of a condition known as acanthosis nigricans typically have minimal skin problems and a good chance of recovery. While rare, complications from this skin condition can occur if the individual also has underlying conditions like diabetes or a resistance to insulin. Fortunately, this form of acanthosis nigricans can often be improved with suitable treatment.
On the other hand, people with the malignant, or harmful, form of acanthosis nigricans generally have a poor prognosis. This is because, typically, the associated malignant conditions are far advanced by the time the skin condition is diagnosed in these patients.
Possible Complications When Diagnosed with Acanthosis Nigricans
The type of complications a person may experience from acanthosis nigricans, a skin condition that causes dark patches, largely depends on what caused it. Most of the time, this condition arises from the body’s resistance to insulin. However, it can also be associated with severe situations, such as the development of cancer.
Potential Complications:
- Insulin resistance
- Association with serious diseases like cancer
Preventing Acanthosis Nigricans
It’s important for patients to understand that darkened patches on the skin might not just be a skin issue and should be checked further, especially in those who are middle-aged or elderly. If you notice any unusual dark patches on your skin, you should talk to your regular doctor about it.
These dark spots, caused by a skin condition known as acanthosis nigricans, can be treated and sometimes even completely cleared up with the right skin treatment or by managing the condition that’s causing it. Being aware of the risk factors, as well as knowing how to spot the signs and symptoms of a serious condition linked to acanthosis nigricans is vital.
Lastly, it’s worth noting that acanthosis nigricans can sometimes lead to feelings of depression and low self-confidence. If this is the case, it’s important to recognize these feelings early on and seek help for your mental well-being alongside the treatment for the skin condition.