Androgenetic Alopecia: The Brown Peripilar Sign

BPPS: Brown peripilar sign in AGA

Dermatoscopic image showing the brown peripilar sign.

Dermatoscopic image showing the brown peripilar sign.

It is increasingly clear that androgenetic alopecia (ie male and female genetic hair loss or “balding) is an inflammatory condition. Even though the scalp typically looks non-inflamed, scalp biopsies show that there is inflammation present just a few millimeters beneath the scalp in an area known as the isthmus and infundibulum. Studies have shown that inflammation occurs quite early in the course of androgenetic alopecia. This inflammation is believed to facilitate the progressive miniaturization of hair follicles.

Although the scalp usually looks fairly normal and non-inflammatory in patients with androgenetic alopecia, evaluation of the scalp via dermoscopy techniques may also show features that suggest there is inflammation under the scalp.

The 2004 Deloche Study

In 2004, Deloche and colleagues from France performed a nice study of 40 patients with androgenetic alopecia. The researchers showed that the brown discolouration around hairs that is seen with dermoscopy correlated nicely with inflammation under the scalp when evaluated by biopsy. They called this the peripilar sign (PPS). “Peri” means around and pilar means hair. The peripilar sign is known by many names as well including the “brown peripilar sign (BPPS)” and “peripilar halo.” Included here is a patient with androgenetic alopecia whose scalp hairs show the BPPS (photo below).

Treating Inflammation in AGA: Yes or No?

It’s almost a certainty that the inflammation needs to be treated in order to best stop hair loss. Modern medicine does not quite know how to best do this yet. There are many different types of anti-inflammatory treatment including corticosteroids, doxycycline, tacrolimus, TNF-inhibitors, immunomodulatory and immunosuppressants. It’s a bit of a guess as to how best to address the inflammation in AGA and more research is needed. It’s extremely likely this will play a beneficial role, particularly the earlier such anti-inflammatory treatment is started. Whether current treatments like antiandrogens or laser actually help with reducing inflammation is not known yet.


Deloche C et al. Histological features of peripilar signs associated with androgenetic alopecia. Arch Dermatol Res. 2004.

Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Whistler office at 604.283.1887

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