A sebaceous filament is a tiny collection of sebum and dead skin cells around a hair follicle, which usually takes the form of a small hair-like strand. They usually have white or yellow color, and can be expressed from the skin by pinching. These filaments are naturally occurring, and are not a sign of infection or any other ailment. They help to channel the flow of sebum within a given skin pore, allowing it to seep gradually to the surface. David A. Whiting described them in his review in the Western Journal of Medicine as "a loose, porous mass of horny detritus". Sebaceous filaments are usually only notable around the thin skin of the nose.