Comedo

A comedo is a form of primary acne lesion, which presents as a small bump or spot on the skin. It arises due to the blockage of a hair follicle by excessive sebum and dead skin cells. Comedones can manifest in two major forms: open (blackheads) and closed (whiteheads). Despite being benign in nature, comedones can lead to psychological distress due to their impact on appearance.

Nose with Blackhead 2009

Pathophysiology

The formation of a comedo begins with the plugging of a hair follicle. This is often initiated by an overproduction of sebum, an oily substance produced by the sebaceous glands, in conjunction with an accumulation of dead skin cells. These factors lead to the formation of a keratinous plug, creating a favorable environment for the growth of the bacterium Cutibacterium acnes. The metabolic activity of this bacterium may further contribute to follicular obstruction and inflammation, leading to the development of visible acne lesions.

Blausen Skin Pores

Types of Comedones

Comedos Nose 01

Comedones are primarily classified into two types:

Open comedones (blackheads): These are dilated hair follicles filled with keratin, bacteria, and sebum. The black color is due to the oxidation of sebum rather than dirt. They are usually painless. Closed comedones (whiteheads): These are smaller, flesh-colored papules that are filled with sebum and skin debris. They are covered by a thin layer of skin which prevents the contents from oxidizing and becoming black.

Diagnosis and Treatment

Diagnosis of comedones is typically based on clinical examination. The appearance of blackheads and whiteheads on the skin is usually indicative of the condition.

Treatment for comedones primarily involves topical applications aimed at unclogging pores and reducing sebum production. These include retinoids, salicylic acid, and benzoyl peroxide. In some cases, extraction using a comedone extractor may be performed by a dermatologist. Lifestyle modifications such as maintaining proper skin hygiene and a balanced diet can also help manage the condition.

See Also

• Acne vulgaris
• Hair follicle
• Sebaceous gland
• Cutibacterium acnes

References

Comedo Resources
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