Follicular streamers are residual fibrovascular tracts representing the impermanent lower third of the hair follicle below the bulge region. Streamers are generally not counted in transverse alopecia samples as they may represent catagen/telogen (CT) follicles and vellus-like (VL) follicles, or be mistaken as follicular scars.Design
We evaluated 22 non-scarring alopecia cases, including alopecia areata (AA) and androgenetic alopecia (AGA), and 22 scarring alopecia cases, including follicular degeneration syndrome (FDS)/central centrifugal cicatricial alopecia and other scarring alopecia (OSA) disorders. We counted terminal follicular streamers found at a deep dermal level (L2) and followed them into a mid-dermal level at the central follicular unit (FU) to determine their precise derivation.Results
We found streamers in 8/9 AA, 11/13 AGA, 6/12 FDS and 3/10 OSA cases. We counted a total of 74 streamers at L2, including 61 in non-scarring alopecia cases (p < 0.001). At the more superficial FU level, 72% of streamers corresponded to CT follicles, 25% to VL follicles and 3% to follicular scars.Conclusions
Follicular streamers are found predominantly in non-scarring alopecia cases. Streamers found at deep dermal or subcutaneous levels should be followed and identified at the FU level in order to obtain accurate follicular counts and follicular ratios needed for non-scarring alopecia diagnosis.