Acne vulgaris:


General: results from clogged pilosebaceous units (comedones), forms pustules, papules, nodules, and comedones (open v. closed),  commonly affects adolescents, family history is important, affects face, neck, and upper trunk/arms, psychosocial effects


Pathogenesis: androgens increase sebum production, sebum and keratin clog the pilosebaceous unit to form a comedo, bacteria (cutibacterium/propionibacterium acnes) grow and cause inflammatory response, certain medications (steroids, testosterone), tight clothing/pressure on the skin


Classification: comedonal, inflammatory (papulopustular), nodulocystic, mild or severe depending on extent of acne, scarring


Complications: post-inflammatory hyperpigmentation, scarring


Treatments: can take 2-3 months to see effect, adherence is key, using a daily ceramide-containing moisturizer can help
 

- Topical retinoids: vitamin A derivative, normalizes differentiation of epithelial cells, prevents new comedones from forming, promotes clearing of comedones, can cause dryness, itching, redness, scaling, sensitive skin (use sunscreen!), available as adapalene, tretinoin creams, lotions, solutions, avoid use during pregnancy 


- Benzoyl peroxide: kills bacteria via free radical production, available as creams, lotions, washes, can cause bleaching and irritation


- Topical retinoid at bedtime, benzoyl peroxide wash in the morning


- Antibiotics: topical erythromycin 2%, topical clindamycin 1%, can be irritating and can cause dry skin, often prescribed w benzoyl peroxide to prevent resistance, oral antibiotics (tetracycline, macrolides) can be used for moderate to severe inflammatory acne but make sure to consider side effect profiles and patient's age/pregnancy status 


- Oral isotretinoin: retinoic acid derivative, used for severe acne unresponsive to other treatments, can cause dry skin and lips, elevated LFTs and triglycerides, teratogenic


- For mild acne, use topical retinoid or benzoyl peroxide, for moderate acne use combo therapy of retinoid and benzoyl peroxide plus a topical antibiotic, for severe acne add oral antibiotic  


- For comedonal acne use topical retinoids, for inflammatory/papulopustular acne start w retinoids/benzoyl peroxide then add topical antibiotics for moderate and oral antibiotics for severe, for nodulocystic acne use topical retinoid/benzoyl with topical antibiotic, do oral antibiotic if severe, oral isotretinoin if unresponsive, can use adapalene for sensitive skin 


- For pediatric patients, consider underlying systemic problems, avoid tetracyclines in patients with age < 8


- Spironolactone and OCPs can treat acne via decreasing amount of androgens 


Avoid over-the-counter products, harsh scrubs, excessive washing


Diet can contribute; low-glycemic carbs are good, *chocolate and greasy foods do not have significant effect on acne*


References: AAD Basic Dermatology Curriculum, Dermatology by Bolognia et. al., Lookingbill and Mark's Principles of Dermatology, First Aid USMLE Step 1 2020, First Aid USMLE Step 2 CK