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The Informed Parent

Dermatographism

by Louis P. Theriot, M.D., F.A.A.P.
Published on Dec. 31, 2014
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Ten-month-old Tyler came to the office with a chief complaint of being allergic to something. He is a blond haired, blue-eyed portly baby with an intense interest in his surroundings. He tries to grab anything within reach and put it in his mouth…this includes my stethoscope and pen.

Sitting in mom’s lap while I took the history, he seemed completely normal and happy, in no distress. The chart information showed that he had no fever and his vital signs were normal. When I asked mom about her concerns, she lifted up his shirt and said, “I’m afraid that Tyler is allergic to something but I just don’t know what it could be. For probably the past three weeks he has been getting these hives all over his body.” She pointed to obvious hives, or welts, on his trunk. There were about three of them, red, raised and actual welts. They didn’t seem to follow any particular pattern, nor did they bother him. Mom concurred that he did not itch them or even know they are there. When asked if they were typically on his trunk she indicated that he had more in his inner thighs/groin area. Removing the diaper, he did have some hives in the inner thighs, symmetrical on the right and lefty leg.

Mom explained that she had removed all cow’s milk products from his diet, used no creams or lotions on his skin, and even banished the pet dog to the grandparent’s house much to the consternation of all family members…all to no avail. She added that grandma thought Tyler needed allergy testing and may need to see a specialist.

While I was talking to mom, I scooted my chair next to hers. Tyler was sitting in her lap, and I began playing with him, getting him to laugh. Then I took a tongue depressor and broke it in half, creating a blunt tipped pointer. I took his arm and on the inner part of the forearm gently scratched a large X. He thought this was hilarious and gave out a belly laugh. Then I had mom stand up, holding him facing her and I made a large O on his back. Again, he found this quite amusing. But mom seemed a bit perplexed by this exercise. I asked her to sit down with Tyler in her lap so that we could talk about dermatographism which is what I thought Tyler had.

Within minutes of all of this Tyler had an obvious red streak exactly where I had scratched. In another 1-2 minutes this evolved into a raised, whitish welt with a red border. The welt formed a perfect X and O. Mom shook her head and said that these are exactly what he has been getting for the past three weeks.

Dermatographism is a common phenomenon that occurs in around 2-5% of the general population. But it has been reported to occur in anywhere from 15-24% of all children. The translation of dermatographism means “to write on the skin”. It is a form of urticarial or hives, and in children it is a benign and self-resolving condition.

It is caused by direct trauma to the skin that causes the release of histamine from circulating most cells near the surface of the skin. The histamine is what causes the hive-like reaction. The hive usually appears within minutes of the trauma, and disappears within 15-30 minutes. Although there have been reports of some hives lasting for a day or so, these are very rare. Dermatographism has been divided into two main categories, simple and symptomatic.

SIMPLE DERMATOGRAPHISM refers to the hives mentioned above in Tyler’s case. They come and go within minutes, and do not cause any itching or symptoms. Almost all cases of dermatographism in the young pediatric patient are of this type.

SYMPTOMATIC DERMATOGRAPHISM  refers to hives that are also caused by trauma, but these are also associated with itching or burning. These are seen mostly in adults and can also be associated with other forms of trauma such as cold, heat or even emotional trauma. One must also look for other associated factors such as medications, thyroid disease and kidney disease.   

Tyler’s mom shook her head in disbelief as the hives had almost disappeared by the time we finished our visit. I explained to her that this was not in any way dangerous or serious. This kind of reaction would never cause any airway or breathing problem nor would he need an Epi-Pen for emergencies. He could resume milk products in his diet and essentially do his normal routine. If these did prove to be a problem (cosmetic?) he could take an allergy medication such as Zyrtec. Mom stopped me before I even finished my sentence “As long as I know what is causing this, and it obviously doesn’t bother him, I would rather not medicate him if I didn’t have to”, she said emphatically. I told her that I couldn’t agree with her more.   

I told her that the majority of cases of simple dermatographism resolve completely within a matter of a few years. It is not something that progressively gets worse. Tyler was thoroughly happy playing with the tongue depressor and mom seemed relieved that it was not a more serious condition. As I stood up and shook her hand I added, “You might want to go and rescue the family dog as his sentence has been suspended.” “I’m calling the grandparents as we speak”, she said with a chuckle.




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