Role of Elastic Verhoef Van Gieson (EVG) Elastic Staining for Differentiating Scarring and Non Scarring alopecia
Follicular streamers are a normal part of the scalp. They are remnants of the lower part of the hair follicle. When seen in lower parts of the scalp, they remind us that a full hair follicle was once there. There presence often indicates the presence of a catagen or telogen hair or a vellus like hair that is part of androgenetic alopecia. Therefore follicular streamers are commonly seen in the non scarring alopecias. Of course, they can be seen in scarring aloepcias but are less common.
Study 1: Hohenstein and Jacob 2008
In 2008, Hohenstein and Jacob from New Jersey set out to look more closely at follicular streamers in a variety of different hair loss conditions. They evaluated 22 non‐scarring alopecia cases, including alopecia areata (AA) and androgenetic alopecia (AGA), and 22 scarring alopecia cases, including central centrifugal cicatricial alopecia (CCCA) and other scarring alopecia (OSA) disorders.
The authors found streamers in 8/9 AA, 11/13 AGA, 6/12 CCCA and 3/10 OSA cases. Of 74 streamers in total that were recorded, 61 of them (82.4%) were from non scarring alopecias (p < 0.001) and only a minority were from the scarring alopecias. In general, most streamers corresponded to catagen and telogen hairs (72%) and 25 % corresponded to vellus like hairs from androgenetic alopecia. Only 3 % of the streamers actually better classified as true follicular scars.
Tan T et al. 2018
In 2018, Tan and colleagues from Norwestern University in Chicago used a special histological stain known as the elastic Verhoef van Gisen stain (EVG) to differentiate follicular streamers from follicular scars on horizontal scalp biopsy sections. They studied 64 scarring alopecias (25 lichen planopilaris, 29 central centrifugal cicatricial alopecias, and 10 discoid lupus erythematosus) and 53 noncicatricial alopecias (34 androgenic alopecia, 8 telogen effluvium, and 11 alopecia areata), and EVG staining was performed on horizontal sections.
In follicular “ streamers”, EVG highlighted an intact elastic network composed of delicate and thin elastic fibers circumferentially surrounding the angiofibrotic streamer. There was no elastic network attenuation, loss, clumping, thickening, or recoil. In contrast in the so called follicular “scars”, EVG demonstrated central attenuation and loss of the elastic network with peripheral clumping and recoil of elastic fibers.
These authors concluded that EVG staining can be helpful in cases where distinguishing between follicular streamers and scars is difficult. This stain may allow better discrimination between cicatricial and noncicatricial alopecias.
Understanding the differences between follicular streamers and follicular scars is important. Follicular streamers are common in non scarring alopecias and usually represent a catagen telogen follicle or a follicle where a vellus hair once lived. They are rare in scarring aloepcias. Follicular scars however, are very much a part of scarring alopecia and are associated with elastin clumping, loss and disarray. These fine details help differentiate challenging cases.
Tan T et al. Elastic staining in differentiating between follicular streamers and follicular scars in horizontal scalp biopsy sections. Am J Dermatopathology 2018; 4:254-258.
Hohenstein M and Jacob J. Follicular streamers (stelae) in scarring and non‐scarring alopecia. . J Cutan Pathol. 2008 Dec;35(12):1115-20.
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