comedone

Comedones are the most common non-inflammatory lesions of acne, resulting from blockage of the pilosebaceous unit by keratinous debris and sebum. They occur in two forms: open comedones, or blackheads, where the pore remains open and a dark apex is visible, and closed comedones, or whiteheads, where the pore is occluded by keratinous material and appears as a small white or flesh-colored bump.

Pathophysiology involves abnormal keratinization of the follicular epithelium, increased sebum production, and accumulation of keratin and sebum within the follicle. Open comedones appear dark due to oxidation of melanin and lipids at the skin surface, not primarily because of dirt. Comedones can occur alone or as part of acne vulgaris; hormonal influences, puberty, and certain medications can raise the risk.

Clinical features include small, non-inflammatory lesions most commonly on the face (especially the forehead, nose, and chin) and sometimes on the chest or back. Open comedones present as visible dark or blackened pores; closed comedones present as small, white or flesh-colored bumps. Diagnosis is clinical; differential diagnoses include milia or keratin plugs in hair follicles. Inflammatory lesions may develop if comedones become irritated or infected.

Management aims to prevent new comedones and promote clearing of existing ones. Topical retinoids (such as tretinoin or adapalene) normalize desquamation and help prevent plugging. Keratolytics like benzoyl peroxide and salicylic acid reduce blockage and have anti-inflammatory effects. Professional extraction of open comedones can be performed by trained personnel; home extraction is discouraged due to scarring risk. For women, hormonal therapies (combined oral contraceptives or anti-androgens) may help in hormonally influenced cases. Regular noncomedogenic skincare and sun protection support prevention.