My 15-year-old daughter was diagnosed with type 1 at the age of three. She now has acanthosis nigricans, but is not overweight at all. She participates in sports 15 hours in a week. What could this mean? The endocrinologist doesn’t know what it is or could be. Are there more cases like this?

There are several different types of acanthosis nigricans, a darkening and often thickening of the skin that commonly occurs at skin folds, such as under the arms, around the neck (back of neck seems to be more common than front of neck), or umbilical area. I’ve also seen it on the labia and elbows and fingers. It commonly occurs in patients who experience excessive insulin, such as a patient with type 2 diabetes. It would seem highly unlikely for your daughter to have type 2 diabetes. Does she treat excessively with insulin, enough to cause lows?

Acanthosis nigricans is not specific for diabetes. There are forms/cases of acanthosis nigricans that are familial, related to obesity, drug-induced, and insulin resistance in polycystic ovary syndrome (PCOS). What are your daughter’s periods like? Does she have excessive body hair, especially as might be rather unusual for a teenage girl, such as on the face or chest or back? There are rare forms of acanthosis nigricans that have been associated with abdominal cancers, again, highly unlikely in a 15-year-old girl. Still, there are other forms of acanthosis nigricans that seemingly are unexplained and are called “idiopathic.” So, as you can see, acanthosis nigricans is primarily simply a cosmetic issue that can represent some other medical conditions.

You might want to talk with a dermatologist or review matters with the pediatric endocrinologist involved in your daughter’s care, especially if she has irregular periods and/or has excessive body hair.

DS