A study of dermoscopic features of nail psoriasis: the pseudo-pseudo-fiber sign

I have read with interest the article published by Yorumalz and Artuz [1] concerning, among other nail psoriasis characteristics, the finding of a new “pseudo-fiber sign”. Identification of sensitive and specific dermatoscopic signs of nail psoriasis can be crucial in the diagnosis of subtle disease. However, I have never seen this finding as proposed by the authors, furthermore I have some comments regarding the pictures presented. The “pseudo-fibers” as illustrated in Figures 8 and 12 appear caught as well in focus as the nail keratin, within anatomical recesses of the cuticle or underneath the nail free edge, well displaced from the site where nail apparatus’ capillaries are normally found. Figure 17 shows some greenish debris and Figure 14 clearly shows that a red “pseudo-pseudo-fiber” jumps over the proximal/lateral nail fold onto the nail. The authors should clarify if the pictures are from the same patient and if the patient has the habit of wearing wool mittens.
The investigators should have highlighted that their conclusions regarding the “pseudo-fiber sign” were based on clinical empirical grounds alone, and not based on any sort of ultrasound examination or biopsy and such testing should have been performed beforehand. I believe these to be real fibers caught on a dystrophic nail given that they blatantly diverge from anything to be expected, even from the pathological process of nail psoriasis, and are merely artefactual.

References

1. Yorulmaz A, Artuz F. A study of dermoscopic features of nail psoriasis. Adv Dermatol Allergol 2017; 34: 28-35.