Sebaceous filament

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, yellow to off-white hair-like strand when expressed from the skin. These filaments are naturally occurring, and are especially prominent on the nose. They are typical among those with naturally oily skin and large pores, even if those individuals have ceased to produce acne. They are not a sign of infection or any other ailment including acne, and are commonly mistaken for, though cannot form, blackheads. In 1979, David A. Whiting described them in a review in the Western Journal of Medicine as "a loose, porous mass of horned detritus".^[1] Although sebaceous filaments cannot be permanently removed, there are methods to help manage them.

Sebaceous filament
Other names	Blackhead (mistakenly)
A 14-year-old with characteristic black kind of sebaceous filaments on the nose
Specialty	Dermatology
Treatment	Retinol topical cream

Anatomy and Physiology

In order to understand the anatomy of sebaceous filaments, it is important to understand sebaceous glands. Skin contains hair follicles, and within these hair follicles are sebaceous glands. These glands secrete an oily substance known as sebum. Sebum protects and lubricates the skin, and also keeps hair healthy and strong. Sebaceous glands are found throughout the entire body (excluding palms and soles), but they are densely located on the face, especially the nose. Sebaceous filaments help move sebum to the surface of the skin, and are composed of sebum and dead skin cells that collect and form a plug within the hair follicle. If there is an increased production of sebum, these sebaceous filaments can become larger and more noticeable.^[2][3] Additionally, sebocytes actively participate in innate immunity by releasing cytokines like IL-1α, IL-6, and TNF-α.^[4]

Appearance and Characteristics

Sebaceous filaments usually appear as small, flat, circular spots on the skin, commonly on the nose. They tend to be a lighter color, ranging from yellowish to gray to translucent. If squeezed, a thin, waxy string of filament comes out of the pore.^[5] This can sometimes leave a small circular hole in the skin.

Sebaceous filaments and blackheads are often mixed up, but they are not the same thing. While sebaceous filaments are a natural component of our pore anatomy, blackheads (open comedones) are considered to be acne. They are caused by the pore becoming clogged with bacteria, dead skin, and sebum. They appear on the skin as black, raised bumps, and can vary in size. After a blackhead heals, it may not come back. Sebaceous filaments do not disappear (even with management) since they are a natural part of our anatomy and required to bring sebum to the skin surface.^[6]

Causes and Risk Factors

There are a variety of factors that contribute to the formation of sebaceous filaments^[7]:

• Age
  • Puberty
    • More sebum is produced by the body, which results in larger sebaceous filaments
  • Elderly
    • Skin loosens, which enlarges pores and makes it easier to see filaments
• Genetics
  • Some individuals naturally make more sebum, which results in larger sebaceous filaments
  • Individuals with thicker hair have larger hair follicles, resulting in more visible sebaceous filaments
• Dry Skin
  • Dry skin triggers the body to create more sebum in order to lubricate the skin