April 2006

Fig. 2

Fig. 3

Diagnosis: loose anagen hair syndrome

Discussion:

Loose anagen hair syndrome is a hair disease first reported by Zaun in 1984. It is a sporadic or familial disorder that primarily affect children. The condition is characterized by anagen hairs of abnormal morphology resulting in easily and painlessly pluckable hairs. This is due to defective anchoing of the hair shaft to the hair follicle. Loose anagen hair syndrome has been reported only in Caucasians. It is more common in females than in males. The clssic patient with this disorder is a girl aged 2-5 years with blond hair.

Commonly, the parents report that the child's hair is thinning and that a haircut is needed very infrequently. Accidental traction during playing often yields clumps of painlessly removed hair. Affected children are healthy and free of nutritional deficiencies. Their development is normal. Physical exam reveals a sparse growth of thin fine hair, sometimes diffuse or patchy alopecia without inflammation or scarring. A hair pull test normally yields 0-2 hairs per pull in healthy individuals, but in loose anagen hair syndrome, the number extracted is much higher. In a normal person, only telogen hairs are pulled during a gentle pull test. However, in loose anagen hair syndrome, a gentle pull test results mainly in anagen hairs.

Under the light microscope (Figs.2 & 3), the epilated hairs are predominantly in anagen phase. The proximal end demonstrates a distorted hair bulb that is often bent at a acute angle to the hair shaft. The hairs lack an inner or outer root sheath. The cuticle has a characteristic ruffled or rippled, baggy stocking appearance.

In loose anagen hair syndrome, mutations in the gene encoding for the companion-layer keratin (K6HK) might explain the characteristics of the loosely attached hair. Another possible candidate may be the gene encoding for the new keratin (K61RS) specific for the inner root sheath. This suggests that the genetic basis of loose anagen hair syndrome may involve more than one gene encoding keratins expressed in the inner root sheath and in the companion layer (the inner most layer of the outer root sheath).

No treatment is currently available. Patient's parents need to be reassured that this is only of cosmetic concern and it usually improves with increasing age.

References:
1. Chapalain, et al. Is the loose anagen hair syndrome a keratin disorder? 2002 Arch. Dermatol. 138: 501-506
2. Tosti.A. and Piraccini., B.M. Loose anagen hair syndrome and loose anagen hair 2002 Arch Dermatol. 138:521-522
3. Chong, A. H. and Sinclair, R. 2002 Loose anagen syndrome: A prospective study of three families Australasian Journal of Dermatology 43:120-124
4. Lee, A.J., Maino, K. L., Cohen, B. and Sperling, L 2005 A gilr with loose anagen hair syndrome and uncombale, spun-glass hair Pediatric dermatology 22:230-233

Presented by Dr. Wei-Wei Huang and Dr. Susan Mallory.