Gentle hair pull can diagnose pediatric alopecia.
COEUR D'ALENE, IDAHO -- The most important test in determining the cause of diffuse hair loss in children and adolescents is a gentle hair pull, Dr. Elise A. Olsen said at the annual meeting of the Society for Pediatric Dermatology.
"This is something you should do in all patients with alopecia, accompanied by looking under the microscope at the hair you've pulled. Grasp a small clump of hair close to the scalp and gently pull through to the ends. It's important that you do it not just in one area but all over, in various places on the scalp. Coming away with three or four hairs per pull is abnormal. Be especially gentle in young children because you can actually induce what looks like a loose anagen syndrome, confusing the picture," explained Dr. Olsen, professor of dermatology and medicine and director of the hair disorders research and treatment center at Duke University in Durham, N.C.
She described how to use the hair pull and other tools to differentiate between telogen effluvium, alopecia areata, androgenetic alopecia, loose anagen syndrome, and short anagen syndrome.
This condition is characterized by a global decrease in hair density. This global reduction can be confirmed by performing a midline part on the back and top of the scalp, which should show a similarly widened, thinned part.
Microscopic examination of the proximal end of all hairs that come off with hair pulls in an adolescent with telogen effluvium should show them to be telogen hairs.
"If you see any anagen hairs, that's abnormal, and I would urge you to think about another condition, like loose anagen syndrome or alopecia areata," Dr. Olsen said.
Potential etiologies of telogen effluvium include stress, thyroid disease, medication side effects, vitamin A intake in excess of 15,000 IU/day, and numerous diet or nutritional deficits.
"Diet is incredibly important in figuring out the cause of telogen effluvium, particularly in children and adolescents, where you might be dealing with bulimia, anorexia nervosa, or another abnormal diet," according to the dermatologist.
The relationship between hair loss and iron deficiency is a matter of long-standing controversy. Low iron levels have often been linked to hair loss. As yet, however, there is no well-controlled clinical trial showing that iron replacement improves telogen effluvium in an iron-deficient patient.
Isotretinoin tons the list of medications that can cause telogen effluvium in pediatric patients. Other drugs that need to be considered include sodium valproate, antidepressants, lithium, and medications for attention-deficit / hyperactivity disorder.
Vitamin supplements should be stopped for at least 24 hours before conducting screening laboratory testing in a patient with telogen effluvium. Dr. Olsen recommended ordering a CBC with differential; thyroid-stimulating hormone and free thyroxine; serum ferritin; total iron binding capacity; and an erythrocyte sedimentation rate to screen for occult inflammatory conditions, which would skew the ferritin results. While a serum ferritin less than 40 ng/mL ordinarily has 98% sensitivity and specificity for iron deficiency, the bar rises to less than 70 ng/mL in patients with any kind of underlying systemic inflammation.
This form of diffuse hair loss can look clinically just like telogen effluvium. The key distinguishing feature is a positive hair pull showing not only telogen hairs but dystrophic, "exclamation point" anagen hairs as well.
"These anagen hairs are broken off or bayonet-like in appearance, and there's usually a distortion of the hair shaft diameter as well," she explained.
Scalp dermoscopy will show yellow dots of keratinaceous debris in the empty follicles of patients with alopecia areata, an uncommon condition in children.
The most useful clue in differentiating this condition from telogen effluvium is that a midline part will be widened on the central scalp but never over the occiput. The gentle hair pull typically doesn't yield any hairs except in affected areas on the top portion of the scalp. Any hairs produced via the hair pull will be telogen hairs, and they will typically vary in diameter. Dermoscopy may show perifollicular pigmentation in areas of hair loss.
"If you diagnose alopecia areata in an adolescent, there are some key things you need to discuss with the parents," Dr. Olsen stressed.
For example, their child is likely to have a more rapidly progressive course of hair loss. And affected girls are at increased risk for underlying hyperandrogenemia-related symptoms, including hirsutism, insulin resistance, polycystic ovarian syndrome, and metabolic syndrome. A finding of acanthosis nigricans in a nonobese teen is a very good indicator that they may have underlying insulin resistance.
Loose anagen syndrome
This condition, whose onset is usually before 8 years of age, is characterized by short, very slow-growing hair. The hair pull yields anagen hairs, which under the microscope have a distinctive appearance marked by a rolled-up proximal tip.
Short anagen syndrome
The hallmarks here are decreased hair density, increased shedding, and an inability to grow hair long. On the hair pull, affected patients have an increased number of telogen hairs. The telogen hairs, which are newly regrowing in response to the truncated anagen cycle, will have a tapered tip at the distal end.
Scalp biopsy is of variable utility in diagnosing the cause of diffuse hair loss in young patients. It can be used to make the diagnosis of certain conditions, including acute alopecia areata, trichotillomania, connective tissue disease, infection, tumor, and scarring disorders. However, scalp biopsy can't be used to make a definitive diagnosis of telogen effluvium, androgenetic alopecia, or long-standing alopecia areata--it can be only suggestive.
Pathologic standards dictate that the scalp biopsy should always be 4 mm. Normal white adults have roughly 36 follicles per 4-mm biopsy. African American adults have about 22. While no standard numbers have been established for children, the number of follicles per biopsy is higher than in adults because of the child's smaller head size. After all, the number of follicles present at birth is what an individual will carry throughout life, Dr. Olsen explained.
It's important that patients and parents understand the need for patience regarding hair regrowth, which takes 6-12 months after the cause of alopecia has been identified and eliminated. That means, for example, that in a patient with thyroid disease the clock for regrowth starts ticking not at the time treatment begins, but when the patient becomes euthyroid.
Dr. Olsen reported serving as a consultant to Canfield Scientific and Allergan.
Caption: "Coming away with three or four hairs per pull is abnormal," explained Dr. Elise A. Olson.
Please note: Illustration(s) are not available due to copyright restrictions.
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|Publication:||Family Practice News|
|Date:||Aug 1, 2014|
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