Comedones

Comedones are non-inflammatory lesions of the pilosebaceous unit characterized by a plug of keratinous material and sebum that blocks the hair follicle. They are typically categorized as open comedones (blackheads), where the follicular opening is visible on the skin surface, and closed comedones (whiteheads), where the opening is occluded and the plug remains beneath the skin.

Pathophysiology of comedones involves hyperkeratinization of the follicular infundibulum with increased sebum production. The keratin and sebum accumulate, forming a plug that can enlarge the follicle. When the opening is exposed to air, oxidation of melanin in the material gives open comedones their dark color; closed comedones appear as pale or flesh-colored bumps.

Clinically, comedones are most often seen in acne vulgaris but can occur independently. They are common during adolescence due to hormonal changes and may persist into adulthood. Contributing factors include genetic susceptibility, cosmetic occlusion, friction, certain medications, and environmental influences. While comedones are non-inflammatory, they may precede inflammatory lesions if bacteria colonize the plugged follicle.

Diagnosis is clinical, based on appearance. Management aims to prevent blockage and promote turnover of the follicular epithelium. Treatments include topical retinoids (such as adapalene or tretinoin), keratolytics (salicylic acid), and sometimes benzoyl peroxide to reduce bacterial load. In some cases, manual extraction by a clinician may be performed with proper sterile technique. For persistent or widespread comedones, dietary, hormonal, or systemic therapies may be considered under medical supervision.

Prognosis is variable; with appropriate therapy, comedones can improve, but relapse is common without ongoing maintenance and avoidance of comedogenic products.