# Slideshow: Acne Visual Dictionary - Author: **WebMD** - Document Tags: [[acne]] - [URL link](https://www.webmd.com/skin-problems-and-treatments/acne/ss/slideshow-acne-dictionary)  ## Highlights - A [comedo](https://www.webmd.com/skin-problems-and-treatments/acne/how-to-remove-a-comedo), or basic acne lesion, is a hair follicle that has become clogged with oil and dead skin cells. Comedones (the plural of comedo) can develop into bumps called whiteheads and blackheads ([View Highlight](https://read.readwise.io/read/01hwyf0b9rzdwsa0n02tcezsqs)) --- - noncomedogenic" is less likely to clog pores ([View Highlight](https://read.readwise.io/read/01hwyf0xmsq2b7grnweqgrhfr5)) --- - [Blackheads](https://www.webmd.com/skin-problems-and-treatments/acne/how-get-rid-blackheads) are comedones that are open at the surface of the skin ([View Highlight](https://read.readwise.io/read/01hwyf2dvdnvhtjy5hv1za1rs3)) --- - Comedones that stay closed at the surface of the skin are called whiteheads ([View Highlight](https://read.readwise.io/read/01hwyf26zbr04x586wg66dwy6p)) --- - Papules are comedones that become inflamed, forming small red or pink bumps on the skin ([View Highlight](https://read.readwise.io/read/01hwyf53q0bcr1gnpbrgtzerbm)) --- - Acne mechanica is caused by heat, friction, and pressure against the skin ([View Highlight](https://read.readwise.io/read/01hwyfadvp0v7ca6y3ykx0k10t)) ---