Skin & Subcutaneous Tissue

Acne vulgaris: outpatient stepwise management

Clinical Overview and When to Suspect Acne Vulgaris

— Follicular hyperkeratinization (microcomedone formation)

— Sebum overproduction (androgen-driven)

— Cutibacterium acnes (formerly Propionibacterium acnes) proliferation

— Perifollicular inflammation (innate immunity, IL-1, TLR-2)

— Classic distribution: face (T-zone), upper chest, shoulders, upper back — areas dense in sebaceous glands

— Mixed lesion types in the same patient: open comedones (blackheads), closed comedones (whiteheads), inflammatory papules/pustules, nodules, cysts

— Polymorphic eruption is the hallmark — monomorphic lesions should prompt reconsideration (see below)

— Sudden severe cystic onset with fever, arthralgias, leukocytosis → acne fulminans (treat as dermatologic urgency)

— Acne + hirsutism + irregular menses + acanthosis nigricans → screen for PCOS / hyperandrogenism

— Pre-pubertal acne (<7 yr) → evaluate for precocious puberty, CAH, adrenal/gonadal tumor

— Monomorphic pustules on trunk after steroids/EGFR inhibitors → drug-induced acneiform eruption, not true acne

— Periorificial papules sparing vermilion border → perioral dermatitis, not acne

Board pearl: The single most important question on a Step 3 acne stem is "Is there scarring or nodulocystic disease?" — if yes, you skip ahead in the ladder and consider systemic isotretinoin referral early rather than cycling through topicals for months.

Definition: Chronic inflammatory disease of the pilosebaceous unit driven by four pathogenic pillars

Epidemiology: Affects ~85% of adolescents aged 12–24; persists into adulthood in ~50% of women and ~25% of men. Peak severity at ages 14–17 (F) and 16–19 (M).

When to suspect (and when not to call it "just acne"):

Red flags suggesting a non-acne or syndromic process:

Severity grading (clinical, not formal): mild (comedonal ± few papulopustules), moderate (numerous papulopustules ± few nodules), severe (widespread nodulocystic or scarring).

Presentation Patterns and Key History

— Duration, onset relative to puberty, prior treatments and adherence/duration (most patients quit topicals at 2–4 weeks — before clinical benefit, which takes 8–12 weeks)

— OTC products tried (benzoyl peroxide, salicylic acid, adapalene 0.1% now OTC)

— Skincare routine: over-washing, scrubbing, comedogenic cosmetics, occlusive sunscreens

— Mechanical/occlusive triggers: helmets, chinstraps, masks ("maskne"), phone pressure

— Medications: corticosteroids, anabolic steroids, lithium, phenytoin, isoniazid, iodides, EGFR inhibitors, progestin-only contraceptives (especially levonorgestrel IUD or implant)

— Diet: high-glycemic-index diets and skim milk have modest evidence for flare association; chocolate and greasy food do not

— Menstrual pattern: perimenstrual flares, hirsutism, alopecia → hyperandrogen workup

— Psychosocial: depression, anxiety, social withdrawal, school avoidance — acne carries measurable QoL burden

— Comedonal acne (forehead, chin) — typical adolescent onset

— Inflammatory papulopustular acne — most common presenting phenotype

— Nodulocystic acne — males > females, trunk-predominant, high scarring risk

— Adult female acne — jawline/perioral, premenstrual flare, often hormonally driven

— Acne mechanica — friction sites, monomorphic

— Acne excoriée — picked lesions, often with underlying anxiety/OCD spectrum

Step 3 management: Always document prior treatment duration, not just the drug name. A patient who "failed adapalene" after 3 weeks has not failed it — set expectations of 8–12 weeks per regimen and rebook at that interval. This adherence-counseling step is itself testable as the best next step before escalating therapy.

Core history elements to elicit at the visit:

Pattern recognition:

Family history: strong heritability; first-degree relative with severe acne predicts severity and isotretinoin need.

Physical Exam Findings and Severity Assessment

— Non-inflammatory: open comedones (dilated follicle with oxidized keratin = "blackhead") and closed comedones ("whitehead," 1–2 mm flesh-colored papule). These define the comedonal phenotype.

— Inflammatory: erythematous papules (<5 mm), pustules (purulent center), nodules (>5 mm, deep, tender), cysts (fluctuant, suppurative).

— Sequelae: post-inflammatory erythema (lighter skin) vs post-inflammatory hyperpigmentation (darker skin, Fitzpatrick IV–VI) vs scars (ice-pick, boxcar, rolling, hypertrophic, keloidal — especially mandible/sternum).

— Mild: mostly comedones, <10 inflammatory lesions, no nodules

— Moderate: 10–40 inflammatory lesions ± few nodules, trunk involvement

— Severe: numerous nodulocystic lesions, scarring, or any acne fulminans/conglobata features

— Hirsutism (Ferriman–Gallwey score), androgenetic alopecia, acanthosis nigricans → hyperandrogenism workup

— Truncal striae, moon facies, buffalo hump → exogenous/endogenous Cushing

— Fever, malaise, painful joints, friable hemorrhagic crusted nodules → acne fulminans — admit, urgent derm

— Interconnected sinus tracts in axillae/groin/inframammary → hidradenitis suppurativa (often coexists)

Key distinction: Rosacea lacks comedones and shows centrofacial erythema + telangiectasias ± ocular symptoms. If you don't see a single comedone, the diagnosis is probably not acne vulgaris — reconsider rosacea, perioral dermatitis, or folliculitis.

Systematic skin exam: Examine face, neck, chest, upper back, shoulders, scalp margin under good lighting. Document lesion count categories rather than exact numbers.

Lesion taxonomy — must distinguish on exam:

Severity grading for treatment decisions:

Findings beyond the skin that change management:

Photograph at baseline (with consent, ideally standardized lighting) — objective measure of response, supports prior-auth for isotretinoin and hormonal therapy.

Diagnostic Workup — When (and When Not) to Order Tests

— Adult female with sudden-onset acne, treatment-resistant acne, or acne + hirsutism/alopecia/oligomenorrhea/infertility/acanthosis nigricans

— Pre-pubertal acne in young children (<8 yr girls, <9 yr boys)

— Virilization signs (clitoromegaly, voice deepening, rapid muscle gain) → urgent workup

— Total testosterone and free testosterone (or SHBG to calculate free) — markedly elevated → ovarian/adrenal tumor

— DHEAS — elevated → adrenal source (CAH, adrenal tumor)

— 17-hydroxyprogesterone (morning, follicular) — screen for non-classical CAH (21-hydroxylase deficiency); >200 ng/dL → ACTH stimulation test

— LH:FSH ratio, prolactin, TSH — PCOS workup and exclude mimics

— Consider fasting glucose, HbA1c, lipid panel — PCOS metabolic comorbidity

— Pregnancy test x2 (iPLEDGE-required, see chunk 10)

— LFTs (ALT, AST) and fasting lipid panel (triglycerides) at baseline and ~1 month into therapy; if stable, no need to recheck monthly

— CBC routine monitoring is no longer recommended

CCS pearl: Resist the urge to order a "shotgun" hormone panel on every female with acne. The high-yield triggers are adult-onset, treatment-resistant, or virilizing features — order testosterone + DHEAS + 17-OHP, not a 12-test endocrine workup.

Acne vulgaris is a clinical diagnosis. No labs, imaging, cultures, or biopsies are required for the typical patient. Ordering routine workup on a teenager with classic facial papulopustular acne is low-value care and a likely wrong-answer distractor on Step 3.

Indications to order targeted labs — hyperandrogenism workup:

Initial androgen panel (draw in early follicular phase, off combined OCPs ≥6 wk if possible):

Pre-isotretinoin baseline labs (per current AAD):

Pre-spironolactone labs: baseline potassium and creatinine in older patients or those on ACEi/ARB/NSAIDs/K-sparing meds; routine K monitoring in healthy young women is not required per current evidence.

Diagnostic Workup — Advanced or Confirmatory Studies

— Total testosterone >150–200 ng/dL or DHEAS >700 µg/dL → image to exclude tumor

— Ovarian source → transvaginal pelvic ultrasound

— Adrenal source → CT or MRI of adrenals

— 17-OHP >200 ng/dL (follicular, AM) → ACTH (cosyntropin) stimulation test; 17-OHP >1000 ng/dL post-stim confirms non-classical CAH → endocrine referral

— Suspected Cushing → late-night salivary cortisol, 24-hr urinary free cortisol, or 1 mg overnight dexamethasone suppression (any 1 of the 3 as initial screen)

— Oligo/anovulation

— Clinical or biochemical hyperandrogenism

— Polycystic ovaries on US (≥20 follicles per ovary or volume >10 mL by current AE-PCOS criteria)

— Always exclude thyroid disease, hyperprolactinemia, and non-classical CAH first

— Lesions are monomorphic and atypical (e.g., suspect eosinophilic folliculitis in HIV, Pityrosporum folliculitis, gram-negative folliculitis after prolonged antibiotics)

— Suspected acne fulminans with hemorrhagic crusting vs vasculitis or pyoderma gangrenosum

— Refractory "acne" in adult — rule out cutaneous lupus, sarcoid, demodicosis

— Sudden worsening on long-term oral antibiotic → suspect gram-negative folliculitis (Klebsiella, Enterobacter, Proteus) — culture and switch to isotretinoin

— Painful pustules unresponsive to standard therapy → consider MRSA in select settings

Board pearl: A young woman on doxycycline for 6 months who suddenly develops deep pustules around the nose and central face has gram-negative folliculitis, not "worsening acne." Stop the antibiotic, culture, and refer for isotretinoin — the definitive treatment.

When hyperandrogenism screen is abnormal — next steps:

PCOS confirmation (Rotterdam — 2 of 3):

Biopsy — rarely indicated, but consider when:

Bacterial culture: Not routinely done. Indicated when:

iPLEDGE / REMS documentation (for isotretinoin candidates) is itself a workup step — see chunk 10.

Risk Stratification and Stepwise Management Logic

— Mild comedonal: topical retinoid monotherapy (adapalene, tretinoin, tazarotene, trifarotene)

— Mild papulopustular: topical retinoid + benzoyl peroxide (BPO) ± topical antibiotic (clindamycin) as a fixed combination

— Moderate: topical retinoid + BPO + oral antibiotic (doxycycline or minocycline/sarecycline) ± hormonal therapy in females

— Moderate–severe / scarring / treatment-refractory: add or transition to hormonal therapy (COC, spironolactone) in females, or refer for oral isotretinoin

— Severe nodulocystic, scarring, or acne fulminans/conglobata: isotretinoin (acne fulminans needs concurrent oral prednisone first to prevent flare)

— Always pair an oral antibiotic with benzoyl peroxide to reduce C. acnes resistance

— Never use topical or oral antibiotics as monotherapy — promotes resistance

— Continue topical retinoid as maintenance after clearance to prevent relapse

— Set the 8–12 week reassessment expectation up front

— Address post-inflammatory hyperpigmentation with sun protection + topical retinoid ± azelaic acid

— Non-comedogenic moisturizer to mitigate retinoid irritation

— Gentle non-foaming cleanser BID; avoid scrubbing/astringents

— Broad-spectrum SPF 30+ sunscreen daily — retinoids and doxycycline are photosensitizing

— Failure of 2 appropriate regimens after 12 weeks each

— Severe nodulocystic disease, scarring, acne fulminans/conglobata

— Isotretinoin candidate (some FM physicians prescribe; many refer)

— Diagnostic uncertainty

Step 3 management: The most commonly missed step in primary care acne is maintenance therapy with a topical retinoid after oral antibiotic discontinuation. Stopping all therapy at clearance is the #1 cause of "treatment-resistant" relapse on the next visit.

Match the ladder rung to the severity phenotype:

Universal principles regardless of rung:

Adjuncts that don't change the ladder but help adherence:

When to refer to dermatology:

Pharmacotherapy — Topical First-Line Regimens

— Adapalene 0.1% (OTC) or 0.3% — best tolerated, photostable, can layer with BPO

— Tretinoin 0.025–0.1% — degraded by sunlight and BPO; apply at night

— Tazarotene 0.045–0.1% — most potent; pregnancy category X — avoid in women of childbearing potential without contraception

— Trifarotene 0.005% — selective RARγ; approved for truncal acne

— Mechanism: normalize follicular keratinization, comedolytic, anti-inflammatory

— Counseling: pea-sized amount to whole face nightly; expect purge at 2–4 weeks; full benefit at 12 weeks; moisturize; daily sunscreen mandatory

— Bactericidal against C. acnes, no resistance development

— Use 2.5% or 5% wash/leave-on — equally effective and less irritating than 10%

— Always pair with topical or oral antibiotic to prevent resistance

— Caveats: bleaches fabrics, towels, hair; contact dermatitis in ~2%

— Clindamycin 1% (most common) — never as monotherapy; always with BPO

— Erythromycin — high resistance, falling out of favor

— Minocycline 4% foam — newer, for inflammatory acne

— Dapsone 5% or 7.5% gel — good for adult female and inflammatory acne; safe in G6PD

— Azelaic acid 15–20% — comedolytic, anti-inflammatory, anti-pigmentary — first-line adjunct in skin of color and pregnancy

— Salicylic acid 0.5–2% — mild comedolytic, OTC

— Clascoterone 1% cream — topical androgen receptor inhibitor; first topical with hormonal mechanism, usable in both sexes ≥12 yr

— Adapalene + BPO, clindamycin + BPO, clindamycin + tretinoin, clindamycin + adapalene + BPO (triple combo, newest)

Board pearl: If the vignette says the patient is "using clindamycin gel alone with worsening acne," the best next step is add benzoyl peroxide, not switch antibiotics — BPO both treats and prevents resistance.

Topical retinoids (cornerstone for nearly every acne patient):

Benzoyl peroxide (BPO) 2.5–10%:

Topical antibiotics:

Other topicals:

Fixed-combination products (improve adherence):

Pharmacotherapy — Systemic Agents and Isotretinoin

— Doxycycline 50–100 mg BID — first-line tetracycline; SE: photosensitivity, GI upset, esophagitis (take with water, upright), pill esophagitis

— Minocycline 50–100 mg BID — equal efficacy; SE: vestibular, hyperpigmentation, drug-induced lupus, DRESS, autoimmune hepatitis

— Sarecycline — narrow-spectrum tetracycline, less GI/photosensitivity, $$$

— Limit duration to 3–4 months, then transition to topical maintenance — minimizes resistance and microbiome disruption

— Avoid in <8 yr (tooth staining) and pregnancy

— Always co-prescribe BPO (topical) to suppress resistance

— Combined oral contraceptives — 4 FDA-approved (norgestimate-EE, norethindrone-EE, drospirenone-EE, drospirenone-EE-levomefolate); any low-dose COC works

— Contraindications: smoker ≥35, migraine with aura, prior VTE, uncontrolled HTN, breast cancer, <6 weeks postpartum

— Spironolactone 50–200 mg/day — androgen receptor antagonist; first-line in adult women, often combined with COC; SE: menstrual irregularity, breast tenderness, hyperkalemia (rare in young healthy), diuresis; avoid in pregnancy (feminization of male fetus)

— Dose: 0.5 mg/kg/day initially, titrate to 1 mg/kg/day; goal cumulative dose 120–150 mg/kg over 5–7 months

— iPLEDGE REMS mandatory: 2 negative pregnancy tests before, monthly tests during, 1 after; 2 contraception methods (or abstinence) for females; monthly counseling for all

— SE: cheilitis (universal), xerosis, epistaxis, retinoid dermatitis, transient hypertriglyceridemia, transaminitis, night-vision changes, pseudotumor cerebri (avoid with tetracyclines), arthralgias, hyperostosis with long courses

— Mood/depression/suicide signal: discussed but causality unproven; screen at every visit

— No elective procedures or waxing for 6 mo after course

Step 3 management: Never co-prescribe isotretinoin + tetracycline — both raise intracranial pressure (pseudotumor cerebri).

Oral antibiotics (moderate–severe inflammatory acne):

Hormonal therapy (adult female acne, jawline distribution, premenstrual flare, PCOS):

Oral isotretinoin (severe nodulocystic, scarring, refractory, acne fulminans, conglobata, psychosocial distress):

Special Populations — Elderly and Renal/Hepatic Impairment

— True acne vulgaris is uncommon >40 yr; new-onset adult acne warrants workup

— Differential: rosacea (centrofacial erythema, telangiectasias, no comedones), perioral dermatitis, demodicosis, drug-induced acneiform (steroids, lithium, EGFR/MEK inhibitors), folliculitis, cutaneous lupus

— EGFR-inhibitor acneiform eruption (cetuximab, erlotinib, panitumumab) — monomorphic pustules, no comedones; treat with doxycycline + topical hydrocortisone prophylactically, do not stop oncologic therapy

— Spironolactone: caution in CKD (eGFR <30) or on ACEi/ARB/K-sparing diuretic — risk of hyperkalemia; check K and Cr at baseline and 4–6 weeks

— Doxycycline: no renal adjustment needed — metabolized hepatically, excreted in feces; preferred tetracycline in CKD

— Minocycline: lipophilic, hepatic metabolism; use with caution in severe CKD

— Trimethoprim-sulfamethoxazole (occasionally used for resistant acne): avoid in advanced CKD due to hyperkalemia and creatinine elevation

— Isotretinoin: monitor LFTs at baseline and ~1 month; transaminitis usually resolves with dose reduction; avoid in active hepatitis

— Minocycline: autoimmune hepatitis risk — avoid in chronic liver disease

— Tetracyclines generally: avoid in decompensated liver disease

— Azelaic acid, topical retinoids, BPO, clascoterone: minimal systemic absorption — safe in hepatic disease

— Lithium, phenytoin, isoniazid, iodides, B12 high-dose, corticosteroids, anabolic steroids, progestin-only contraception, EGFR/MEK inhibitors — all can trigger acneiform eruptions

— Step 1 in management: review and modify offending drug if feasible before adding acne therapy

Key distinction: Acneiform eruption from EGFR inhibitors is monomorphic, papulopustular without comedones, appears within 2 weeks of starting therapy, and correlates with tumor response — do not discontinue the oncologic drug; treat the rash.

Acne in older adults — rare but consider:

Renal impairment:

Hepatic impairment:

Polypharmacy concerns (especially relevant in older adults with acneiform eruptions):

Special Populations — Pregnancy, Lactation, and Pediatrics

— Contraindicated (teratogenic): isotretinoin (Category X — retinoid embryopathy: craniofacial, cardiac, CNS, thymic defects), tazarotene (X), spironolactone (feminization of male fetus), tetracyclines after 15 wk (tooth/bone), trimethoprim in first trimester

— Avoid generally: topical tretinoin and adapalene (limited data — most guidelines say avoid out of caution, though systemic absorption is minimal)

— First-line in pregnancy:

— Topical azelaic acid 15–20% — Category B, also helps melasma/PIH

— Topical benzoyl peroxide (limited systemic absorption, considered acceptable)

— Topical clindamycin or erythromycin if needed

— Oral erythromycin for moderate inflammatory acne

— Postpartum/lactation: azelaic acid, BPO, topical erythromycin/clindamycin safe; avoid retinoids and tetracyclines

— Females of childbearing potential must:

— Use 2 forms of contraception (or abstinence) starting 1 month before, during, and 1 month after therapy

— 2 negative urine/serum pregnancy tests before starting (separated by ≥30 days)

— Monthly pregnancy tests during therapy

— One pregnancy test 1 month after completion

— Monthly REMS portal counseling and prescription pickup within 7 days of test

— Neonatal acne (<6 wk) — actually neonatal cephalic pustulosis (Malassezia) — self-resolves; topical ketoconazole if persistent

— Infantile acne (6 wk–1 yr) — true acne, may scar; topical retinoid + BPO; rarely oral erythromycin; refer if severe

— Mid-childhood acne (1–7 yr) — red flag — workup for hyperandrogenism/precocious puberty

— Preadolescent acne (7–11 yr) — comedonal, may herald normal puberty; topical therapy

— Adolescent acne — full ladder applies; tetracyclines safe ≥8 yr

Board pearl: Acne in a 4-year-old is never just acne — bone-age X-ray, growth chart review, and endocrine workup (DHEAS, testosterone, 17-OHP, LH/FSH) come before any prescription.

Pregnancy — what's safe, what's absolutely not:

iPLEDGE / isotretinoin pregnancy program (US-specific, frequently tested):

Pediatric acne:

Complications and Adverse Outcomes

— Post-inflammatory hyperpigmentation (PIH) — disproportionate burden in Fitzpatrick IV–VI; can persist months–years

— Post-inflammatory erythema — more common in lighter skin; fades over weeks–months

— Atrophic scars: ice-pick (narrow, deep), boxcar (wider, sharp edges), rolling (broad, undulating); treat with retinoids early; resurfacing (microneedling, fractional laser, subcision, TCA CROSS) for established scars

— Hypertrophic and keloidal scars: common on jawline, shoulders, chest, back; treat with intralesional triamcinolone, silicone, pressure

— Sinus tracts in conglobate disease — connect cysts; refer for surgical excision + isotretinoin

— Acne conglobata — chronic, deep nodulocystic, interconnected abscesses, draining sinuses, atrophic/keloidal scars; part of the follicular occlusion tetrad (acne conglobata + HS + dissecting cellulitis of scalp + pilonidal cyst)

— Acne fulminans — abrupt severe ulcerative acne + fever, leukocytosis, arthralgia, hepatosplenomegaly, lytic bone lesions; treat with oral prednisone first (4 wks), then add low-dose isotretinoin

— SAPHO syndrome — Synovitis, Acne, Pustulosis, Hyperostosis, Osteitis — multisystem

— Depression, anxiety, social withdrawal, body dysmorphic disorder

— Suicidal ideation risk elevated in moderate–severe acne — screen with PHQ-9

— School/work absenteeism

— Antibiotic resistance (community-level C. acnes and off-target microbiome shifts)

— C. difficile with prolonged tetracyclines (uncommon but reported)

— Isotretinoin: hypertriglyceridemia → pancreatitis (rare), pseudotumor cerebri, IBD signal (controversial, current evidence does not support causation), suicide/depression signal (counsel and screen)

— Spironolactone: hyperkalemia (rare in healthy young women)

— Doxycycline-induced photosensitivity, pill esophagitis

Key distinction: Acne fulminans + isotretinoin started without prior steroids = catastrophic flare. Always start prednisone 0.5–1 mg/kg/day for 4 weeks first, then add low-dose isotretinoin and overlap.

Cutaneous sequelae:

Severe acne variants:

Psychosocial complications (always assess):

Treatment-related adverse events:

When to Escalate — Referral, Inpatient, and Urgent Triage

— Acne fulminans — fever, malaise, arthralgia, hemorrhagic crusted ulcerative nodules; check CBC, ESR, CRP, LFTs, consider bone imaging if focal pain

— Severe DRESS, autoimmune hepatitis, drug-induced lupus from minocycline → stop drug, ED if systemic illness

— Pseudotumor cerebri suspicion in patient on tetracycline ± isotretinoin (headache, vision changes, papilledema) → stop drugs, neurology, LP, MRI/MRV

— Suspected Stevens–Johnson / TEN from any acne drug (rare) → burn unit / ED

— Severe nodulocystic acne or any scarring

— Failure of 2 well-conducted regimens (12 wk each)

— Suspected acne conglobata, hidradenitis suppurativa coexistence

— Need for isotretinoin if PCP not iPLEDGE-enrolled

— Diagnostic uncertainty (suspect lupus, sarcoid, demodicosis)

— Confirmed non-classical CAH, suspected adrenal or ovarian tumor

— Pediatric acne with precocious puberty signs

— Refractory hyperandrogenism after PCOS-directed therapy

— PHQ-9 ≥10, suicidal ideation, body dysmorphic features, acne excoriée

— Especially important in isotretinoin candidates — coordinate with prescriber

— Established atrophic scars after acne is controlled — laser, microneedling, subcision, fillers, TCA CROSS

— Keloids — intralesional triamcinolone, silicone, surgical revision with adjuvant steroid

— Acne fulminans with systemic inflammatory response

— Suspected isotretinoin-associated pancreatitis (TG >1000) or severe DRESS

CCS pearl: On a CCS-style case of a 17-year-old male with sudden severe ulcerative acne, fever 38.8°C, and joint pain — your orders are CBC, CMP, ESR, CRP, blood cultures (if febrile), oral prednisone, admit or urgent derm consult, hold isotretinoin until steroids on board. Starting isotretinoin first is the trap answer.

Same-day urgent dermatology or ED evaluation:

Routine dermatology referral within 2–4 weeks:

Endocrinology referral:

Mental health referral:

Procedural referral:

Inpatient admission — rare in acne, consider when:

Key Differentials — Same-Category (Acneiform & Follicular) Conditions

— Centrofacial erythema, telangiectasias, flushing triggers (heat, alcohol, spicy food), papulopustules without comedones

— Ocular involvement: blepharitis, conjunctivitis, dry eye

— Treatment: topical metronidazole, ivermectin, azelaic acid; brimonidine for erythema; oral doxycycline 40 mg sub-antimicrobial dose for papulopustular; laser for telangiectasias

— Papulopustules around mouth, nose, eyes; spares vermilion border; often triggered by topical/inhaled corticosteroids or fluorinated toothpaste

— Treatment: stop the steroid, topical metronidazole or pimecrolimus, oral tetracycline if severe

— Bacterial (S. aureus): pustules at hair follicles, monomorphic

— Gram-negative folliculitis: after prolonged oral antibiotics for acne; central facial pustules; treat with isotretinoin or appropriate antibiotic per culture

— Pityrosporum (Malassezia) folliculitis: truncal/upper back monomorphic itchy pustules in young adults, worse with humidity/sweat; KOH shows yeast; treat with topical or oral antifungals (ketoconazole), not antibiotics — often misdiagnosed as truncal acne

— Eosinophilic folliculitis: HIV patients with CD4 <250 — pruritic papules on face/trunk

— Hot tub folliculitis (Pseudomonas): self-limited, antibiotics if severe

— Painful recurrent nodules, abscesses, sinus tracts in intertriginous areas (axillae, groin, inframammary, buttocks)

— Often coexists with severe acne — part of follicular occlusion tetrad

— Treatment: lifestyle, topical clindamycin, oral tetracyclines, adalimumab for moderate-severe, surgical excision

— Posterior neck/occiput, predominantly in Black men; follicular papules → keloidal plaques

— Avoid close-cut shaving, topical/intralesional steroids, laser

Board pearl: Truncal "acne" that itches and worsens after gym/sweat in a young adult is Pityrosporum folliculitis — KOH and a 2-week trial of oral fluconazole or topical ketoconazole is the diagnostic-therapeutic move.

Rosacea:

Perioral (periorificial) dermatitis:

Folliculitis variants:

Hidradenitis suppurativa (HS):

Acne keloidalis nuchae:

Key Differentials — Other-Category Mimics

— Corticosteroids (oral, topical, inhaled): monomorphic papulopustules, no comedones, sudden onset; "steroid acne"

— Anabolic-androgenic steroids: severe nodulocystic, trunk-predominant, in athletes/bodybuilders

— EGFR inhibitors (cetuximab, erlotinib): early treatment-related papulopustular eruption — correlates with response

— MEK inhibitors, BRAF inhibitors, mTOR inhibitors: similar acneiform pattern

— Lithium, phenytoin, isoniazid, B12, iodides/bromides, danazol, halogens

— Progestin-only contraception (levonorgestrel IUD, etonogestrel implant, DMPA): worsens acne; switch to combined OCP if acne intolerable

— PCOS — full workup if hirsutism + irregular menses

— Cushing syndrome — moon facies, buffalo hump, striae, central obesity, easy bruising, proximal myopathy

— Congenital adrenal hyperplasia (non-classical) — adult-onset hyperandrogenism, sometimes confused with PCOS

— Androgen-secreting tumors — virilization, rapid onset

— Discoid lupus — scarring, photodistributed plaques, follicular plugging — biopsy

— Cutaneous sarcoidosis — periorificial papules, scar infiltration

— Pyoderma faciale (rosacea fulminans) — sudden severe facial pustules/nodules in young women, abrupt onset, no comedones

— Demodicosis — older adults, perifollicular pustules, refractory to acne therapy; skin scraping shows Demodex; treat with permethrin or ivermectin

— Molluscum contagiosum — umbilicated papules, not pustular

— Furunculosis (MRSA) — recurrent painful boils, often family clusters; decolonization

Key distinction: No comedones = not acne vulgaris. Comedones are the pathognomonic primary lesion of acne. A monomorphic pustular eruption without comedones is almost always a mimic — usually drug-induced, rosacea, or folliculitis.

Drug-induced acneiform eruptions (always review the med list):

Endocrine mimics:

Inflammatory dermatoses:

Infectious mimics:

Hidradenitis suppurativa, acneiform syndromes (PAPA, PASH, PAPASH) — multisystem auto-inflammatory; refer rheumatology/dermatology.

Maintenance, Secondary Prevention, and Long-Term Plan

— Topical retinoid is the cornerstone — continue indefinitely or for at least 6–12 months after clearance to prevent microcomedone recurrence

— Adapalene 0.1% is best evidence for long-term maintenance

— Continue BPO wash 2–3x/week if prior oral antibiotic exposure to keep C. acnes suppressed

— Some adult women remain on spironolactone or COC long-term — reassess annually

— ~70% achieve durable remission; ~30% need second course or transition to topical maintenance ± hormonal therapy

— Resume topical retinoid 1–2 months post-course as maintenance

— Counsel: avoid pregnancy 1 month after; defer elective laser/dermabrasion/waxing 6 months; avoid concomitant tetracyclines

— Low-glycemic-index diet — modest benefit

— Reduce skim milk — modest evidence; whole milk less implicated; whey protein supplements can worsen acne in male athletes

— No evidence that chocolate or greasy food cause acne — don't reinforce myths

— Daily SPF 30+ broad-spectrum sunscreen — prevents PIH and is mandatory with retinoids/tetracyclines

— Non-comedogenic, oil-free cosmetics and hair products

— Stop scrubbing, exfoliating brushes, astringents

— Hands off the face; clean phones; replace pillowcases regularly

— Sun protection + topical retinoid + azelaic acid (or hydroquinone short-term) — first-line, especially in skin of color

— Avoid aggressive peels that may worsen pigmentation

Step 3 management: When a patient with previously controlled acne returns with relapse 3 months after stopping all therapy, the best next step is resume topical retinoid maintenance, not restart oral antibiotic. Re-treat the underlying microcomedone, not the inflammation.

Maintenance after clearance (the most under-prescribed component):

After isotretinoin:

Lifestyle and trigger reduction (evidence-based counseling):

Scar prevention is treatment of active acne — early aggressive therapy of inflammatory/nodulocystic disease prevents the scars patients will spend thousands trying to remove later.

PIH management:

Follow-Up, Monitoring, and Counseling Cadence

— Initial visit: confirm diagnosis, grade severity, baseline photos, start regimen, set 8–12 week expectations, address adherence and skincare

— Week 8–12 follow-up: assess response, modify regimen — step up if no improvement, address tolerability

— Every 3 months while on oral antibiotic — assess for resistance, side effects, plan exit to topical maintenance by 3–4 months

— Every 4 weeks on isotretinoin (iPLEDGE-required) — pregnancy test, labs at month 1 (LFTs, fasting lipids), symptom/mood screen, dose titration

— Annual reassessment for patients on long-term hormonal therapy (spironolactone, COC) — BP, K (only if indicated), menstrual history

— Doxycycline/minocycline: symptom-based; no routine labs; counsel photosensitivity, esophageal irritation; minocycline >1 year — LFTs and ANA if symptoms

— Spironolactone: baseline K and Cr in higher-risk patients; routine K monitoring in healthy women <45 is not required per recent evidence (large cohort data)

— COC: annual BP; reassess VTE risk factors

— Isotretinoin: baseline + month 1 LFTs and fasting lipids; if normal and stable, no further routine labs needed; monthly pregnancy testing per iPLEDGE

— Hormonal workup follow-up: repeat testosterone/DHEAS 3 months after intervention

— Adherence (the #1 cause of "failure"): when, where, how much, what irritation

— Sun protection

— Pregnancy plans and contraception (especially before any retinoid or spironolactone)

— Mood and quality of life — brief PHQ-2 or PHQ-9 in moderate-severe disease

— Set realistic expectations: clearance, not cure; relapses common; lifelong skincare

Board pearl: A patient on isotretinoin with a missed monthly pregnancy test cannot pick up the next prescription until the window resets — iPLEDGE non-compliance is a hard stop, even with documented abstinence.

Visit schedule (outpatient FM template):

Monitoring parameters by drug:

Counseling checklist at every visit:

Telehealth: Acne is well-suited to virtual follow-up; standardized photos enable quantitative tracking.

Ethical, Legal, and Patient Safety Considerations

— Mandatory federal program for isotretinoin in females of childbearing potential

— Pregnancy on isotretinoin → ~30% risk of major embryopathy → report to the iPLEDGE pregnancy registry and MedWatch

— Document counseling, contraception methods, and test dates in the EHR — medicolegal protection

— 7-day prescription pickup window — pharmacy partnership essential

— Minors on isotretinoin: most states require parental consent; adolescent assent best practice; document discussion of mood/depression risk and need to report symptoms

— Contraception counseling for minors: in most US states minors can consent to contraceptive services without parental involvement; document confidentiality discussion

— Spironolactone in transgender patients: acne worsens with masculinizing hormone therapy; coordinate with gender-affirming care provider; spironolactone is also used for feminizing effects in transfeminine patients — different dosing and goals

— Document baseline mood screen before isotretinoin; mood worsening on therapy → reassess, refer, consider dose reduction or discontinuation

— Acne excoriée and body dysmorphic disorder require concurrent mental health care — treating the skin alone fails

— Patient lost to follow-up while on oral antibiotic >3–4 months → antibiotic stewardship failure; build EHR reminder

— Hand-off from PCP to dermatologist for isotretinoin — share labs, prior regimens, and contraception counseling notes

— Postpartum: medications safe in pregnancy may differ from those safe in lactation — review at 6-week postpartum visit

— Co-prescribing tetracycline + isotretinoin → pseudotumor cerebri

— Spironolactone + ACEi/ARB/K supplement in older patient → hyperkalemia

— Long-term doxycycline in adolescent → microbiome and resistance concerns

— Mail-order isotretinoin schemes bypassing iPLEDGE — illegal in US, counsel against

Step 3 management: A 16-year-old asks for confidential contraception to start isotretinoin without telling her parents. In most US jurisdictions she can consent to contraception; parental consent is still required for isotretinoin itself. Coordinate, don't refuse.

iPLEDGE / REMS as patient safety architecture:

Informed consent edge cases:

Mental health and dermatology overlap:

Transitions of care risk points:

Patient safety pitfalls:

Equity considerations: Insurance prior-authorization frequently delays isotretinoin and topical combination products; document failed first-line therapies thoroughly to facilitate appeal.

High-Yield Associations and Rapid-Fire Clinical Facts

— C. acnes is anaerobic, lipophilic, gram-positive rod within follicles

— Androgen surge at adrenarche (DHEA-S rise ~age 7–8) precedes pubarche and acne onset

— Microcomedone is the primary subclinical lesion preceding all visible acne — explains why retinoids work as maintenance

— Acne + hirsutism + oligomenorrhea → PCOS

— Acne + galactorrhea → check prolactin

— Acne + muscle gain + testicular atrophy → anabolic steroid abuse

— Acne + striae + central obesity → Cushing

— Acne in a 4-year-old → CAH, precocious puberty, adrenal tumor

— Acne + arthralgia + fever + ulcerative skin → acne fulminans

— Acne + axillary nodules and sinus tracts → hidradenitis suppurativa

— Acne + scalp dissecting cellulitis + pilonidal cyst → follicular occlusion tetrad

— Acne + bone pain + sterile osteitis → SAPHO syndrome

— Tetracycline + isotretinoin → pseudotumor cerebri (avoid)

— Minocycline → drug-induced lupus, autoimmune hepatitis, blue-gray skin pigmentation, DRESS

— Spironolactone → hyperkalemia (rare in young women), feminization of male fetus → contraception mandatory

— Doxycycline → photosensitivity, pill esophagitis

— BPO → bleaches fabric and hair

— Isotretinoin → teratogenic, dry lips (100%), elevated triglycerides

— Isotretinoin cumulative goal: 120–150 mg/kg

— Acne therapy reassessment interval: 8–12 weeks

— Oral antibiotic course limit: 3–4 months, then off

— iPLEDGE pregnancy tests: 2 before, monthly during, 1 after

— Wait 6 months post-isotretinoin before elective resurfacing procedures

— Adapalene 0.1% — now OTC (since 2016)

Board pearl: When a question describes "monomorphic papulopustules without comedones" in a patient on a new medication — the answer is drug-induced acneiform eruption, and the test wants you to identify the offending drug, not start standard acne therapy.

Pathophysiology pearls:

"If you see X, think Y":

Drug-disease memory hooks:

Numbers worth memorizing:

Board Question Stem Patterns

17-year-old with mild papulopustular acne tried "adapalene for 3 weeks" without improvement.

→ Best next step: continue current therapy and reassess at 12 weeks (or add BPO), not switch agents. Tests adherence-counseling principle.

19-year-old with previously controlled acne stops all therapy at 6 months and relapses 3 months later.

→ Restart topical retinoid as maintenance — not antibiotics. Tests microcomedone concept.

Patient on topical clindamycin alone for 4 months with worsening.

→ Add benzoyl peroxide (or switch to fixed combination). Tests resistance prevention.

28-year-old woman with jawline acne flaring premenstrually, no response to doxycycline.

→ Start spironolactone ± COC. Tests adult female phenotype recognition.

5-year-old with comedonal acne and pubic hair.

→ Order DHEAS, testosterone, 17-OHP, bone age — workup for precocious puberty/CAH, not treat.

Pregnant patient at 14 weeks with moderate inflammatory acne.

→ Topical azelaic acid + topical erythromycin or BPO. Avoid retinoids, tetracyclines, spironolactone.

16-year-old male starts isotretinoin and develops fever, joint pain, hemorrhagic crusted nodules.

→ Stop isotretinoin, start oral prednisone, urgent derm, restart isotretinoin only after steroid coverage.

Patient on lung cancer therapy with cetuximab develops monomorphic facial pustules.

→ Continue oncologic drug, treat with topical hydrocortisone + doxycycline. Don't stop chemotherapy.

Acne patient on doxycycline x6 months develops new central facial pustules.

→ Discontinue antibiotic, culture, refer for isotretinoin.

Patient on isotretinoin misses month-3 pregnancy test by 2 days.

→ Cannot dispense; wait for window reset and repeat counseling.

Key distinction: The exam rewards you for recognizing patterns that interrupt the standard ladder — pediatric age, adult female, pregnancy, drug-induced, fulminans, gram-negative. Default ladder questions are easy; deviation cases are where points are won and lost.

Stem 1 — Adherence trap:

Stem 2 — Maintenance failure:

Stem 3 — Antibiotic monotherapy:

Stem 4 — Hormonal acne:

Stem 5 — Pediatric red flag:

Stem 6 — Pregnancy:

Stem 7 — Acne fulminans:

Stem 8 — Drug-induced acneiform:

Stem 9 — Gram-negative folliculitis:

Stem 10 — iPLEDGE compliance:

One-Line Recap

Acne vulgaris is a chronic four-pillar pilosebaceous disease whose outpatient management is a stepwise ladder — topical retinoid + benzoyl peroxide ± topical antibiotic for mild–moderate disease; oral tetracycline (always paired with BPO, capped at 3–4 months) and hormonal therapy (spironolactone or COC in adult women) for moderate–severe disease; and isotretinoin (iPLEDGE-governed) for nodulocystic, scarring, or refractory disease — with topical retinoid maintenance, sun protection, and treatment of mimics being where most exam points and most clinical relapses are won or lost.

Rapid recap bullets:

Diagnose clinically; comedones are pathognomonic. Monomorphic pustules without comedones = mimic (drug, rosacea, folliculitis, perioral dermatitis). No routine labs; workup only for hyperandrogenism, pediatric age, or pre-isotretinoin.

Match severity to ladder rung and reassess at 8–12 weeks. Mild → topical retinoid ± BPO; Moderate → add oral tetracycline + BPO (or hormonal in adult women); Severe/scarring → isotretinoin. Never use antibiotics (topical or oral) as monotherapy. Cap orals at 3–4 months, then transition to topical retinoid maintenance.

Special populations dictate drug choice: pregnancy → azelaic acid, BPO, erythromycin (avoid retinoids, tetracyclines, spironolactone); pediatric < 8 yr → no tetracyclines, evaluate for hyperandrogenism if mid-childhood; adult female with hormonal pattern → spironolactone ± COC; severe + systemic features → suspect acne fulminans, give prednisone before isotretinoin.

Patient safety nonnegotiables: iPLEDGE compliance (2 pregnancy tests before, monthly during, 1 after; 2 contraception methods); never combine tetracycline + isotretinoin (pseudotumor cerebri); always pair antibiotics with BPO to suppress resistance; screen mood at every isotretinoin visit; daily SPF for all retinoid and tetracycline users.