Which skin disorder is characterized by the presence of comedones?

The correct answer is acne vulgaris, which is specifically characterized by the presence of comedones. Comedones are clogged hair follicles (pores) that can be open or closed. When the opening of the comedo is dilated, it is referred to as an open comedo or blackhead, and when it is closed, it is known as a closed comedo or whitehead.

Acne vulgaris develops when sebaceous (oil) glands produce excess sebum, and this oil, along with dead skin cells, accumulates in the hair follicles. The blockage of the follicles leads to the formation of both open and closed comedones. This condition is common during adolescence due to hormonal changes but can affect individuals at any age.

In contrast, rosacea is primarily characterized by redness, flushing, and potential pustules but does not typically involve comedones. Dermatitis refers to inflammation of the skin and may present with redness and scaling but does not specifically produce comedones. Fungal infections generally present with other symptoms like itching and scaling rather than comedones. Thus, acne vulgaris stands out as the skin disorder specifically associated with comedones.