Friday, November 9, 2018
Acne vulgaris is a common chronic skin disease involving blockage and/or inflammation of pilosebaceous units (hair follicles and their accompanying sebaceous gland). Acne can present as noninflammatory lesions, inflammatory lesions, or a mixture of both, affecting mostly the face but also the back and chest.
cne vulgaris is the formation of comedones, papules, pustules, nodules, and/or cysts as a result of obstruction and inflammation of pilosebaceous units (hair follicles and their accompanying sebaceous gland). Acne develops on the face and upper trunk. It most often affects adolescents. Diagnosis is by examination. Treatment, based on severity, can involve a variety of topical and systemic agents directed at reducing sebum production, comedone formation, inflammation, and bacterial counts and at normalizing keratinization.
Acne is the most common skin disease in the US and affects 80% of the population at some point in life.
Pathophysiology
Acne occurs through the interplay of 4 major factors:
Excess sebum production
Follicular plugging with sebum and keratinocytes
Colonization of follicles by Propionibacterium acnes (a normal human anaerobe)
Release of multiple inflammatory mediators
Acne can be classified as
Noninflammatory: Characterized by comedones
Inflammatory: Characterized by papules, pustules, nodules, and cysts
Noninflammatory acne
Comedones are sebaceous plugs impacted within follicles. They are termed open or closed depending on whether the follicle is dilated or closed at the skin surface. Plugs are easily extruded from open comedones but are more difficult to remove from closed comedones. Closed comedones are the precursor lesions to inflammatory acne.
Inflammatory acne
Papules and pustules occur when P. acnes colonizes the closed comedones, breaking down sebum into free fatty acids that irritate the follicular epithelium and eliciting an inflammatory response by neutrophils and then lymphocytes, which further disrupts the epithelium. The inflamed follicle ruptures into the dermis (sometimes precipitated by physical manipulation or harsh scrubbing), where the comedone contents elicit a further local inflammatory reaction, producing papules. If the inflammation is intense, grossly purulent pustules occur.
Nodules and cysts are other manifestations of inflammatory acne. Nodules are deeper lesions that may involve > 1 follicle, and cysts are large fluctuant nodules.
Etiology
The most common trigger is
Puberty
During puberty, surges in androgen stimulate sebum production and hyperproliferation of keratinocytes.
Other triggers include
Hormonal changes that occur with pregnancy or the menstrual cycle
Occlusive cosmetics, cleansers, lotions, and clothing
High humidity and sweating
Associations between acne exacerbation and diet, inadequate face washing, masturbation, and sex are unfounded. Some studies suggest a possible association with milk products and high-glycemic diets. Acne may abate in summer months because of sunlight’s anti-inflammatory effects. Proposed associations between acne and hyperinsulinism require further investigation. Some drugs and chemicals (eg, corticosteroids, lithium, phenytoin, isoniazid) worsen acne or cause acneiform eruptions.
Symptoms and Signs
Skin lesions and scarring can be a source of significant emotional distress. Nodules and cysts can be painful. Lesion types frequently coexist at different stages.
Comedones appear as whiteheads or blackheads. Whiteheads (closed comedones) are flesh-colored or whitish palpable lesions 1 to 3 mm in diameter; blackheads (open comedones) are similar in appearance but with a dark center.
Papules and pustules are red lesions 2 to 5 mm in diameter. Papules are relatively deep. Pustules are more superficial.
Skin Lesion (Pustule) Skin Lesion (Pustule) Skin Lesion (Pustule)
Image provided by Thomas Habif, MD.
Acne (Papules and Pustules) Acne (Papules and Pustules) Acne (Papules and Pustules)
Image provided by Thomas Habif, MD.
Acne With Multiple Pustules Acne With Multiple Pustules Acne With Multiple Pustules
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Acne Affecting the Body Acne Affecting the Body Acne Affecting the Body
© Springer Science+Business Media
Nodules are larger, deeper, and more solid than papules. Such lesions resemble inflamed epidermoid cysts, although they lack true cystic structure.
Cysts are suppurative nodules. Rarely, cysts form deep abscesses. Long-term cystic acne can cause scarring that manifests as tiny and deep pits (icepick scars), larger pits, shallow depressions, or hypertrophic scarring or keloids.
Acne With Abscess Formation Acne With Abscess Formation Acne With Abscess Formation
© Springer Science+Business Media
Acne conglobata is the most severe form of acne vulgaris, affecting men more than women. Patients have abscesses, draining sinuses, fistulated comedones, and keloidal and atrophic scars. The back and chest are severely involved. The arms, abdomen, buttocks, and even the scalp may be affected.
Acne Conglobata (Conglobate Acne) on the Face Acne Conglobata (Conglobate Acne) on the Face Acne Conglobata (Conglobate Acne) on the Face
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Acne fulminans is acute, febrile, ulcerative acne, characterized by the sudden appearance of confluent abscesses leading to hemorrhagic necrosis. Leukocytosis and joint pain and swelling may also be present.
Pyoderma faciale (also called rosacea fulminans) occurs suddenly on the midface of young women. It may be analogous to acne fulminans. The eruption consists of erythematous plaques and pustules, involving the chin, cheeks, and forehead. Papules and nodules may develop and become confluent.
Pyoderma Faciale (Rosacea Fulminans) Pyoderma Faciale (Rosacea Fulminans) Pyoderma Faciale (Rosacea Fulminans)
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Diagnosis
Assessment for contributing factors (eg, hormonal, mechanical, or drug-related)
Determination of severity (mild, moderate, severe)
Assessment of psychosocial impact
Diagnosis of acne vulgaris is by examination.
Differential diagnosis includes rosacea (in which no comedones are seen), corticosteroid-induced acne (which lacks comedones and in which pustules are usually in the same stage of development), perioral dermatitis (usually with a more perioral and periorbital distribution), and acneiform drug eruptions (see Table: Types of Drug Reactions and Typical Causative Agents). Acne severity is graded mild, moderate, or severe based on the number and type of lesions; a standardized system is outlined in Table Classification of Acne Severity.