Short Anagen Syndrome

Short anagen syndrome is a disorder of children with hair that does not grow beyond a short length (usually less than 10 to 15 cm) and excessive shedding, because the growth phase of the hair cycle is short.

It presents between the ages of 2 and 6 years in otherwise healthy children, typically girls. The scalp hair is normal in density at first, with no pigment or shaft abnormality, and haircuts are rarely needed.

It is often an incidental finding. It may be underdiagnosed, and improves in many children by adolescence. A familial pattern is described.

Pathophysiology.

The anagen phase lasts months instead of years, so hair does not reach long lengths, and a greater proportion of follicles are in telogen at any time. The cause is not known, and no gene has been identified.

• Hair that never grows past the shoulders or is short, with fine and sparse appearance and frequent shedding without bald patches.
• Normal general health and development, with no nail, tooth or skin abnormality.
• Persistence into adulthood in some patients.

• Clinical diagnosis from history (no need for haircut, short hair, excess shedding) and examination.
• Pull test positive for telogen hairs (more than 10% of a gentle pull). Trichogram shows a high proportion of telogen hairs (often more than 30%) with normal shaft structure.
• Rule out other causes of excess shedding: full blood count, ferritin, thyroid function and, if indicated, zinc, in children with other symptoms.

Differential diagnosis.

• Telogen effluvium (acute and diffuse, with recovery) and loose anagen hair syndrome (hairs pull out painlessly with a distorted bulb).
• Iron deficiency, hypothyroidism and trichotillomania.
• Alopecia areata incognita and hair shaft disorders.

• Explain the condition and its benign course. No treatment is required.
• Gentle hair care: avoid tight styles, chemicals and heat. Hair can be allowed to grow without cutting.
• Topical minoxidil 2% has been tried in older children with unproven results.
• Correct any deficiency found. Psychological support for the child if teasing occurs.

Monitoring. Review once or twice yearly while hair length is followed.

Referral and escalation. Paediatric dermatology if there is a bald patch, abnormal shafts or other features.