Extraction of Fairly Normal Appearing Anagen Hairs Signifies Active Scarring Alopecia

New Report Documents The Readily Extractable Anagen Hairs in the Setting of Lichen Planopilaris

Hair grows and sheds and grows again. The phase whereby hair grows is called anagen phase. The phase that hair sheds is called exogen phase (which follows the telogen phase). Telogen hair is well known to all of us - because those are the hairs we see every single day. The hairs in the shower, the hairs on our brush, the hairs on our clothing - those are all telogen hairs.

It’s rare to see an anagen hairs. They are generally quite firmly rooted in the scalp. If you want to see an anagen hair, you would need to do some pretty hard yanking and pulling of hair.

Melo RR et al. 2023

Authors of a new case report describe a 32 year old male with lichen planopilaris.

The authors describe that the patient had a “pull test” as part of his routine examination. The pull test was positive and revealed pigmented hair roots on trichoscopy, typical of anagen bulbs. The hairs were surrounded by a translucid root sheath. The patient went on to have a scalp biopsy which confirmed a diagnosis of LPP.

The authors remind us that extraction of anagen hairs is uncommon and strongly suggests cicatricial alopecia in the active phase. The inflammation that is part of the scarring alopecia facilitates the premature release of anagen hairs. The authors remind us that a positive anagen pull test is compatible with active interface dermatitis on histopathology.

Anagen hairs from a positive pull test. FROM; Melo RR et al. Positive Anagen Pull Test Predicting Lichen Planopilaris ActivityDermatol Pract Concept. 2023 Jul 1;13(3):e2023140. IMAGE shared with creative commons license.

Comment

I liked this report. There are several possible findings of a pull test in active lichen planpilaris. The pull test may be negative. It may be positive with anagen hairs, it may be positive with telogen hairs, or it may be positive with both anagen and telogen hairs.

It’s important to remember that a negative pull test does not mean the scarring alopecia is quiet. A positive pull test for anagen hairs always means the scarring alopecia is active but a negative pull test does not mean the scarring alopecia is quiet.

It is important to have a close look at all hairs that come out during a pull test. If the hairs seem to have something attached to them, it’s important to spend time figuring out if this ‘something’ is the external root sheath of an anagen hairs or just scaling or crust or other scalp material that can often just be seen as part of dandruff or seborrheic dermatitis or dermatitis.

As this report reminds us, the finding of fairly normal appearing anagen hairs is a very significant finding as it may signify an active scarring alopecia.

REFERENCE

Melo RR et al. Positive Anagen Pull Test Predicting Lichen Planopilaris ActivityDermatol Pract Concept. 2023 Jul 1;13(3):e2023140.

 1