Acanthosis nigricans (AN) is an odd name. However, this medical condition isn’t new to many. A disorder characterised by dark, thick patches on the skin-fold regions like the axilla, groin and back of the neck, is most frequently linked to diabetes and insulin resistance. It can also occasionally be an indicator of internal malignancy. Sometimes, it can be caused by drugs too, like oral contraceptives or systemic glucocorticoids – anti-inflammatory drugs that work with the immune system to treat a wide range of illnesses.
This condition typically affects people under 40. It may be genetically inherited or linked to obesity, hypothyroidism, polycystic ovary syndrome (PCOS) and insulin resistance. Because of unhealthy lifestyle patterns and related complications, insulin resistance and prediabetes have emerged as the main reason for people to develop this condition.
Acanthosis Nigricans and Diabetes
Bibin J E, a 38-year-old quality health safety and environment project co-ordinator with a private oil and gas firm in the United Arab Emirates who weighed 136 kgs and was suffering from a horde of adverse lifestyle health conditions, including high blood sugar levels, tells Happiest Health how he developed black patches near his neck. It was one of the initial signs that forced him to seek medical help and realise that he was at serious risk of developing type 2 diabetes. However thankfully motivated by his doctor’s advice and his determination to lose weight, he managed to bring down his body weight and also avert the looming threat of diabetes.
The American Diabetes Association has formally recognised AN as a predictor of the development of diabetes. The condition is more common in Native Americans, African Americans and Hispanics than in people of white or Asian origin in the United States.
According to Dr Vijay Viswanathan, head and chief diabetologist, MV Hospital for Diabetes and Research Center, Chennai, AN is a skin marker for insulin resistance. “The condition in which the folds such as the armpits and nape of the neck become more pigmented could result in type 2 diabetes,” confirms Dr Viswanathan, one of the veteran diabetologists and researchers in South India.
Does insulin resistance cause black patches on skin?
Insulin resistance, a condition in which insulin doesn’t work as well as it should, is a sign of the most common type of AN. Insulin, a hormone produced by the pancreas, controls the amount of glucose in the blood by making glucose move into cells to make energy or into the liver and fat cells to store energy. The main source of energy for cell metabolism in the body is glucose, which is a simple sugar. AN is thought to be caused by a build-up of insulin in the blood, which is caused by insulin resistance. Insulin resistance has been linked to several diseases, including obesity, polycystic ovary syndrome (PCOS) and type 2 diabetes.
When insulin resistance is the most frequent cause of AN in children and young adults, basal and glucose-stimulated insulin levels are higher in children with AN compared to obese children without the condition; this is linked to hyperinsulinemia (the amount of insulin in the blood is higher than what’s considered normal) independently of body mass index.
According to studies from both India and the United States, there is a clear connection between acanthosis nigricans and childhood obesity. Regular and adequate physical activity can help to delay the onset of the condition. The high prevalence of AN in women with diabetes is known to be partly or entirely due to PCOS, an insulin-resistant condition.
The build-up of insulin in the blood explains why the body converts carbohydrates into glucose when we eat. While the body stores the remaining glucose, cells use some of it for energy. For cells to use glucose as energy, the hormone insulin must permit glucose to enter the cells. People who are overweight tend to develop resistance to insulin over time. Although the pancreas produces insulin, the body has trouble effectively using it. This causes a build-up of glucose in the blood, which may result in high levels of glucose and insulin in the blood.
Dr Nihal Thomas, professor and head of the department, endocrinology, diabetes, and metabolism, Christian Medical College in Vellore, talks about the different types of acanthosis nigricans. He says that type 3, also referred to as obesity and pseudoacanthosis nigricans, is a very prevalent form. “If the underlying causes, such as insulin resistance, obesity, etc, are treated, this may lessen and even go away. But this may take months or years. Type 1 acanthosis can appear at birth or develop during childhood and is brought on by an autosomal dominant trait. Type 2 AN is related to diabetes and metabolic syndrome. Type 4 acanthosis nigricans is linked to the use of oral contraceptives and growth hormone therapy,” he says.
Benign forms of the condition commonly manifest during childhood or puberty. Benign acanthosis nigricans, which occurs less commonly, may be present at birth or develop after puberty. The latter cases almost always involve acanthosis nigricans in conjunction with obesity (pseudoacanthosis nigricans).
Malignant acanthosis nigricans, usually appears after the age of 40. Experts believe that several factors may point to malignant acanthosis nigricans in combination with underlying cancer. These include adult-onset symptoms that are unrelated to the use of specific medications, obesity, positive family history and certain underlying disorders known to be associated with the condition. On rare occasions, malignant acanthosis nigricans can develop in children.
Dealing with Acanthosis Nigricans
The condition can be reversed and will go away in six to eight months if the person adopts healthy lifestyle habits, says Dr Thomas. Hereditary variants may or may not fade with age, and malignancy-associated variants may fade after a malignancy is removed.
“On the subject of treatment, endocrine-related acanthosis nigricans can be managed by reducing blood sugar levels through diet and exercise. Selenium sulfide-containing creams are used to treat the condition. The causative tumour can be removed to treat malignant acanthosis nigricans. However, it is certain that it can be reversed in a number of scenarios; it may go away if the underlying causes are treated. If it is drug-induced, it disappears when the drug is stopped. Weight loss also helps with obesity-related acanthosis nigricans,” says Dr Thomas.