Occipital hair exhibited considerable vertical strength. Because occipital hair exerted the greatest force and cut hair fragments were found in the pilonidal nest in large quantities, these data suggest that pilonidal sinus disease is promoted by occipital hair. See Video Abstract at http://links.lww.com/DCR/A435.

Short hair fragments with rootless sharp cut ends were found within pilonidal sinus cavities. Morphologically, these fragments resemble short cut rather than intact body hair. Since short cut hair, e.g., derived from the head potentially enters the pilonidal cavity more easily than longer hair, the source of these cut hair fragments needs to be eliminated when aiming to prevent Pilonidal Sinus Disease.

We saw our null hypothesis that "hair in the sinus cavity is from the intergluteal region" rejected by each of three different approaches. There is strong evidence that occipital hair is present regularly in pilonidal sinus nests. We should start thinking of occipital hair as an important hair source for the development of the pilonidal hair nest.