Some more information about sebaceous filaments, and also: beware of marketing!

This post was motivated by the Proactiv blackhead dissolving gel commercial, found here. Early in the commercial, they show an image of blackheads on the skin, but they also show a close-up of a nose with normal sebaceous filaments. The rest of the advertisement goes on to claim how great the product is at busting blackheads.

My beef is with the depiction of sebaceous filaments (which are a normal feature of the skin) as blackheads (acne). So, beware of marketing! Rest assured, your SFs are normal.

Some literature regarding sebaceous filaments: Sebaceous filaments are cylindrical tubes of whitish-yellowish color, which can be expressed from areas of the face rich in sebaceous follicles by pinching the skin or by the cyanoacrylat-technique. Sebaceous filaments are most commonly found in the centrofacial areas and the alae nasae in postpuberal individuals with large facial pores and seborrhea. Sebaceous filaments are composed of a skeleton of 10-30 horny cell layers which enclose a mixture of bacteria, sebaceous lipid, corneocyte fragments and one hair. Following the expression of the filament the follicle refills within 30 days. The various portions of sebaceous follicles (acro- and infrainfundibulum) and the follicular contents are presented at the light microscopial and ultrastructural level. Follicles containing sebaceous filaments have a conspicuous granular layer and no acanthosis. Sebaceous filaments should be differentiated from a microcomedo and trichostasis spinolosa. They are a common morphological variant of sebaceous follicles. (G Plewig, HH Wolff, Sebaceous Filaments, Arch. Derm. Res. 255 (1976) 9-21.

Also, Sebaceous follicles are limited to the face and upper trunk. They are characterized by deep, cavernous follicular canals, wispy hairs, and large sebaceous glands. The terminal fifth of the in-fundibulum, or acroinfundibulum, is lined with normal squamous epithelium. The internal four fifths, or infrainfundibulum, is lined with a glycogen-rich epithelium. Its granular layer is meager and its thin keratin layer lacks a normal laminated structure. It sloughs readily to form a loose, porous mass of horny detritus in the follicular canal, or sebaceous filament, which permits sebum to flow through it. The patency of the infundibulum is not easily maintained as it lacks rigid terminal hairs that act as wicks for the outward flow of sebum. It is not surprising that most acne lesions occur in sebaceous follicles. (DA Whiting, Acne Clinical Review, West J. Medicine 131 (1979) 551-557.)

Edit: Some common means of identifying sebaceous filaments: common in the nose, chin, and forehead area; when squeezed fill back up in 24-48 hours; white, fleshlike, or light-gray colored (not black); when squeezed, express soft material and not a solid plug.