Tuesday, November 11, 2008

Acanthosis Nigricans in a Child

Abstract: 11 yo girl with three year history of acanthosis nigricans

This is a healthy 11 y.o. girl. Her mother noticed gradual darkening of skin in neck folds, axillae and groin around three years ago. The child is Chinese. Has not had her first menstrual cycle yet, although has some breast development. She is mildly overweight (not obese). Fitzpatrick Skin Type IV - V. No hirsuitism.
O/E: Velvety hyperpigmentation of skin folds. There are a few skin tags in axillae. Some perioral darkening
Clinical Photo:

Lab: Insulin Level 43 (nl 3 - 28)
Hgb A1C normal, Serum Testosterone Level 75 (normal < style="font-weight: bold;">Histopathology: N/A
Diagnosis or DDx: Acanthosis Nigricans
This child may have AN associated with obesity or a syndromic AN associated with insulin resistance. Too early to say if PCOS is related. We do not have any pediatric endocrinologists in our area, but I feel that she should travel to see one. Dr. Susan Ratzan has kindly given us some guidelines (see below)
Questions: How would you approach this patient and initiate an appropriate work-up? (See Dr. Ratzan's comments below) Is this high insulin level significant?
Reason(s) Presented: To Discuss implications of this diagnosis and work-up.
1. eMedicine.com

2. Hermanns-Lê T, Scheen A, Piérard GE. Acanthosis nigricans associated with insulin resistance : pathophysiology and management. Am J Clin Dermatol. 2004;5(3):199-203.
Departments of Dermatopathology, University of Liège, Liège, Belgium.

The association of acanthosis nigricans, skin tags, diabetes mellitus due to insulin resistance, and obesity in adolescents and young adults represents a well defined syndrome. Hyperandrogenism may also be present. The endocrine origin of this condition is beyond doubt. Insulin and insulin-like growth factor-1, and their receptors on keratinocytes are obviously involved in the complex regulations leading to the peculiar epidermal hyperplasia. This condition is unrelated to other types of acanthosis nigricans, including the congenital and the paraneoplastic types.Control of obesity contributes largely to reverse the whole process, essentially by reducing both insulin resistance and compensatory hyperinsulinemia. Several drugs including metformin, octreotide, retinoids and topical colecalciferol (vitamin D(3)) analogs are also beneficial in clearing acanthosis nigricans.

Comments by Susan Ratzan, M.D. (pediatric endocrinologist):
As far as I am concerned AN is the cutaneous manifestation of hyperinsulinism or insulin resistance. For starters I would get a very good family history for type 2 diabetes, PCOS, hirsutism, infertility, irregular menses, and obesity. You described her very politely as "chunky" but what is her BMI? The way I would document her degree of insulin resistance/carbohydrate tolerance is by doing a 2 hr oral glucose tolerance test with samples at 0, 30, 60, 90 and 120 minutes for BOTH insulin and glucose. At the 0 sample, since she will be fasting, I would also get cholesterol, LDLdirect, triglycerides and HDL(many of these children have the dyslipidemia associated with metabolic syndrome which is elevated TG and low HDL). The best treatment for insulin resistance, but the most difficult to achieve, is a healthier lifestyle, lots of fresh fruits and veggies, healthy oils, fat free milk, no fast food, no soda or other sugar sweetened beverages and juice limited to 4-6 oz/day. We also recommend limiting carbs to 5-6 servings(and they need to be taught what a serving is)/day. If only I could live like this!! Exercise needs to be worked up to an hour a day by turning off the TV and the video games/internet. If the child has glucose intolerance or severe insulin resistance, we use metformin even in children as young as 11, but nothing works as well as lifestyle change.

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