Insulin Resistance Linked to Acanthosis Nigricans

SAN FRANCISCO — Insulin resistance may be present in patients with acanthosis nigricans, particularly if they are overweight or obese, and research increasingly supports a link between these conditions.

A high level of clinical suspicion may be warranted, Dr. Jeffrey P. Callen said at a seminar on women's and pediatric dermatology sponsored by Skin Disease Education Foundation (SDEF). “Sometimes it is a very subtle finding.”

Dr. Callen, chief of dermatology and professor of medicine at the University of Louisville (Ky.), cited the case of an overweight young woman he saw for acne treatment. She had no menstrual irregularities, which can signal polycystic ovary syndrome, a condition also linked with insulin resistance. “Basically the reason we were alert to the fact that she was insulin resistant is, during her complete examination, we noticed a velvety discoloration on the back of her neck, in a folded area of the skin.”

The patient was referred to her primary care physician and tested positive for insulin resistance.

An insulin sensitizer such as metformin can help such a patient lose weight, after which their acanthosis nigricans would likely improve as well, said Dr. Callen. Some reports in the literature support use of insulin sensitizers to indirectly improve acanthosis nigricans (Ann. Pharmacother. 2008;42:1090–4), whereas others only point to modest benefits (J. Drugs. Dermatol. 2006;5:884–9).

The clinical association became stronger after researchers found 78 (36%) of 216 patients newly diagnosed with type 2 diabetes also had acanthosis nigricans on the back of their necks (Endocr. Pract. 2004;10:101–6). Investigators at the University of Texas Southwestern in Dallas found risk varied by body mass index and ethnicity in this retrospective study. “They found those who had acanthosis nigricans were most often insulin resistant, overweight, and more of them were people of color,” Dr. Callen said. For example, 50 of 95 African American and 28 of 78 Hispanic diabetics in the study had acanthosis nigricans, compared with 1 of 39 whites and 0 of 4 Asians.

More recently, researchers found a higher prevalence of insulin resistance among obese women with acanthosis nigricans, compared with others without the skin hyperpigmentation (J. Dermatol. 2009;36:209–12). Specifically, 5 of 32 participants (16%) with acanthosis nigricans had insulin resistance, compared with none of the 34 women without the dermatologic condition.

Acanthosis nigricans is a clinical diagnosis and histopathology generally is not required. Affected patients often come to a dermatologist “because they've noticed this hyperpigmentation on folded areas of the skin—the back of the neck or under the arms.” Although Dr. Callen sometimes orders fasting and postprandial insulin levels for patients with acanthosis nigricans, he thought most dermatologists would refer a patient for further work-up.

Dr. Callen disclosed no relevant conflicts of interest. SDEF and this news organization are owned by Elsevier.

To see a video of Dr. Callen discussing this association, visit www.youtube.com/SkinAndAllergyNews

SAN FRANCISCO — Insulin resistance may be present in patients with acanthosis nigricans, particularly if they are overweight or obese, and research increasingly supports a link between these conditions.

A high level of clinical suspicion may be warranted, Dr. Jeffrey P. Callen said at a seminar on women's and pediatric dermatology sponsored by Skin Disease Education Foundation (SDEF). “Sometimes it is a very subtle finding.”

Dr. Callen, chief of dermatology and professor of medicine at the University of Louisville (Ky.), cited the case of an overweight young woman he saw for acne treatment. She had no menstrual irregularities, which can signal polycystic ovary syndrome, a condition also linked with insulin resistance. “Basically the reason we were alert to the fact that she was insulin resistant is, during her complete examination, we noticed a velvety discoloration on the back of her neck, in a folded area of the skin.”

The patient was referred to her primary care physician and tested positive for insulin resistance.

An insulin sensitizer such as metformin can help such a patient lose weight, after which their acanthosis nigricans would likely improve as well, said Dr. Callen. Some reports in the literature support use of insulin sensitizers to indirectly improve acanthosis nigricans (Ann. Pharmacother. 2008;42:1090–4), whereas others only point to modest benefits (J. Drugs. Dermatol. 2006;5:884–9).

The clinical association became stronger after researchers found 78 (36%) of 216 patients newly diagnosed with type 2 diabetes also had acanthosis nigricans on the back of their necks (Endocr. Pract. 2004;10:101–6). Investigators at the University of Texas Southwestern in Dallas found risk varied by body mass index and ethnicity in this retrospective study. “They found those who had acanthosis nigricans were most often insulin resistant, overweight, and more of them were people of color,” Dr. Callen said. For example, 50 of 95 African American and 28 of 78 Hispanic diabetics in the study had acanthosis nigricans, compared with 1 of 39 whites and 0 of 4 Asians.

More recently, researchers found a higher prevalence of insulin resistance among obese women with acanthosis nigricans, compared with others without the skin hyperpigmentation (J. Dermatol. 2009;36:209–12). Specifically, 5 of 32 participants (16%) with acanthosis nigricans had insulin resistance, compared with none of the 34 women without the dermatologic condition.

Acanthosis nigricans is a clinical diagnosis and histopathology generally is not required. Affected patients often come to a dermatologist “because they've noticed this hyperpigmentation on folded areas of the skin—the back of the neck or under the arms.” Although Dr. Callen sometimes orders fasting and postprandial insulin levels for patients with acanthosis nigricans, he thought most dermatologists would refer a patient for further work-up.

Dr. Callen disclosed no relevant conflicts of interest. SDEF and this news organization are owned by Elsevier.

To see a video of Dr. Callen discussing this association, visit www.youtube.com/SkinAndAllergyNews

SAN FRANCISCO — Insulin resistance may be present in patients with acanthosis nigricans, particularly if they are overweight or obese, and research increasingly supports a link between these conditions.

A high level of clinical suspicion may be warranted, Dr. Jeffrey P. Callen said at a seminar on women's and pediatric dermatology sponsored by Skin Disease Education Foundation (SDEF). “Sometimes it is a very subtle finding.”

Dr. Callen, chief of dermatology and professor of medicine at the University of Louisville (Ky.), cited the case of an overweight young woman he saw for acne treatment. She had no menstrual irregularities, which can signal polycystic ovary syndrome, a condition also linked with insulin resistance. “Basically the reason we were alert to the fact that she was insulin resistant is, during her complete examination, we noticed a velvety discoloration on the back of her neck, in a folded area of the skin.”

The patient was referred to her primary care physician and tested positive for insulin resistance.

An insulin sensitizer such as metformin can help such a patient lose weight, after which their acanthosis nigricans would likely improve as well, said Dr. Callen. Some reports in the literature support use of insulin sensitizers to indirectly improve acanthosis nigricans (Ann. Pharmacother. 2008;42:1090–4), whereas others only point to modest benefits (J. Drugs. Dermatol. 2006;5:884–9).

The clinical association became stronger after researchers found 78 (36%) of 216 patients newly diagnosed with type 2 diabetes also had acanthosis nigricans on the back of their necks (Endocr. Pract. 2004;10:101–6). Investigators at the University of Texas Southwestern in Dallas found risk varied by body mass index and ethnicity in this retrospective study. “They found those who had acanthosis nigricans were most often insulin resistant, overweight, and more of them were people of color,” Dr. Callen said. For example, 50 of 95 African American and 28 of 78 Hispanic diabetics in the study had acanthosis nigricans, compared with 1 of 39 whites and 0 of 4 Asians.

More recently, researchers found a higher prevalence of insulin resistance among obese women with acanthosis nigricans, compared with others without the skin hyperpigmentation (J. Dermatol. 2009;36:209–12). Specifically, 5 of 32 participants (16%) with acanthosis nigricans had insulin resistance, compared with none of the 34 women without the dermatologic condition.

Acanthosis nigricans is a clinical diagnosis and histopathology generally is not required. Affected patients often come to a dermatologist “because they've noticed this hyperpigmentation on folded areas of the skin—the back of the neck or under the arms.” Although Dr. Callen sometimes orders fasting and postprandial insulin levels for patients with acanthosis nigricans, he thought most dermatologists would refer a patient for further work-up.

Dr. Callen disclosed no relevant conflicts of interest. SDEF and this news organization are owned by Elsevier.

To see a video of Dr. Callen discussing this association, visit www.youtube.com/SkinAndAllergyNews