USMLE Guide: Acne

Introduction

Acne is a common skin condition that affects millions of people worldwide. It is characterized by the presence of pimples, blackheads, and whiteheads on the skin, usually on the face, chest, and back. This guide aims to provide a comprehensive overview of acne for USMLE preparation.

Epidemiology and Risk Factors

• Acne is most prevalent during adolescence, affecting up to 85% of teenagers.
• However, it can persist into adulthood, with around 12% of women and 3% of men experiencing acne in their 30s.
• Risk factors include hormonal changes, family history, increased sebum production, certain medications, and certain cosmetics.

Pathophysiology

1. Increased sebum production: Androgens stimulate the sebaceous glands to produce excess sebum.
2. Hyperkeratinization: Abnormal shedding of skin cells within the hair follicles leads to their accumulation and subsequent blockage.
3. Bacterial colonization: Propionibacterium acnes colonizes the blocked follicles, leading to inflammation.
4. Inflammation: Immune response to P. acnes causes redness, swelling, and the formation of papules, pustules, nodules, and cysts.

Clinical Presentation

• Non-inflammatory lesions: Open comedones (blackheads) and closed comedones (whiteheads).
• Inflammatory lesions: Papules, pustules, nodules, and cysts.
• Acne can cause pain, discomfort, and scarring, leading to psychological distress.

Diagnosis

• Diagnosis is primarily clinical, based on the characteristic appearance of acne lesions.
• Severe or atypical cases may require further evaluation, including hormone testing or skin biopsy.

Treatment

Topical Treatments

1. Retinoids: Normalize keratinization, reduce inflammation, and prevent comedone formation.
2. Benzoyl peroxide: Antibacterial agent that also helps unblock pores.
3. Topical antibiotics: Reduce P. acnes colonization and inflammation.
4. Azelaic acid: Anti-inflammatory and antibacterial effects.

Systemic Treatments

1. Oral antibiotics: Used for moderate to severe inflammatory acne.
2. Hormonal therapy: For women with hormonal acne, oral contraceptives or anti-androgens may be prescribed.
3. Isotretinoin: Reserved for severe, recalcitrant acne, as it carries potential side effects and requires close monitoring.

Procedural Treatments

1. Extraction of comedones: Performed by a dermatologist to remove blackheads and whiteheads.
2. Intralesional corticosteroid injections: For large inflammatory nodules or cysts.
3. Chemical peels: Superficial peels help in comedone removal and exfoliation.
4. Laser and light therapy: Reduce P. acnes and inflammation, and improve scarring.

Complications and Prognosis

• Acne can lead to scarring (atrophic or hypertrophic) and post-inflammatory hyperpigmentation.
• Psychological effects, including depression and anxiety, may occur.
• Early treatment can prevent complications and improve long-term prognosis.

Conclusion

Acne is a prevalent skin condition affecting individuals of various age groups. Understanding its pathophysiology, clinical presentation, diagnosis, and treatment options is essential for medical professionals. By following this USMLE guide, you will gain the necessary knowledge to tackle questions related to acne on the exam.