What type of acne is characterized as open comedones?

The type of acne characterized as open comedones is indeed blackheads. Open comedones occur when hair follicles become clogged with oil and dead skin cells, and the surface remains open. This allows the material within the follicle to oxidize when exposed to air, resulting in the dark appearance characteristic of blackheads.

In contrast, whiteheads are another form of comedonal acne, but they are considered closed comedones. In this case, the clogged follicle is covered by skin, preventing oxidation and resulting in a white or skin-colored bump. Papules are raised, inflamed lesions that may not contain pus and do not have the same characteristics as comedonal acne. Cystic acne involves deeper inflammation and nodules, which can be painful and tend to be larger and more severe than either comedones or papules. These distinctions help in understanding the overall classification of acne, highlighting why blackheads are specifically referred to as open comedones.