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Acneiform Eruptions
- Group of conditions that all look like acne on first pass, but behave differently
Acne Vulgaris
- Chronic inflammatory disorder of the pilosebaceous unit (hair follicle + oil gland)
- Caused by increased sebum production, follicular hyperkeratinization, Cutibacterium acnes, and inflammation
- Most common in adolescents and young adults
Clinical Presentation
- Hallmark: open comedones (blackheads) and closed comedones (whiteheads)
- Inflammatory papules, pustules, nodules, or cysts
- Distribution: face, chest, back, shoulders
- Post-inflammatory hyperpigmentation or scarring may occur
- The question stem would likely describe a teenager with comedones and inflammatory lesions on the face or back
Diagnostics
- Clinical diagnosis
- No labs or imaging required
Treatment
- Mild: Topical retinoids ± benzoyl peroxide
- Moderate: Add topical or oral antibiotics (doxycycline, minocycline)
- Severe (think depth, not numbers) or nodulocystic: Oral isotretinoin
- Hormonal therapy options in women: combined oral contraceptives, spironolactone
Exam Keys
- Comedones = acne vulgaris
- First-line therapy is a topical retinoid
- Isotretinoin is reserved for deeper cystic or nodular lesions
- Oral antibiotics should always be combined with topical therapy
- Oral antibiotics are used short-term and should not be monotherapy
Folliculitis
- Infection or inflammation of hair follicles
- Most commonly caused by Staphylococcus aureus
- May be bacterial, fungal, or mechanical in origin
Clinical Presentation
- Small erythematous pustules centered on hair follicles
- Mild tenderness or pruritus
- Common locations: beard area, buttocks, thighs
- The question stem would likely describe pustules centered around hair follicles after shaving or sweating
Diagnostics
- Usually a clinical diagnosis
- Culture if recurrent or refractory
Treatment
- Mild: Topical mupirocin or clindamycin
- Extensive or recurrent: Oral antibiotics (cephalexin, dicloxacillin)
- Reduce friction and occlusive clothing
Exam Keys
- Pustules centered on follicles suggest folliculitis
- Most cases are due to Staph aureus
- Treat topically unless disease is extensive
- Hot tub exposure → think Pseudomonas folliculitis (often self-limited)
Perioral Dermatitis
- Inflammatory facial eruption surrounding the mouth
- Often caused or made worse with topical corticosteroid use
- Most common in young women
Clinical Presentation
- Small erythematous papules and pustules around the mouth
- Spares the vermillion border
- No comedones
- Often worsens with continued steroid use
- The question stem would likely describe a young woman with perioral papules after chronic topical steroid use
Diagnostics
- Clinical diagnosis
Treatment
- Discontinue topical corticosteroids (expect rebound flare)
- Topical metronidazole or clindamycin
- Oral doxycycline for moderate to severe cases
Exam Keys
- Perioral papules sparing the vermillion border = perioral dermatitis
- Absence of comedones helps rule out acne vulgaris
- Treat with antibiotics, not steroids
Rosacea
- Chronic inflammatory disorder affecting the central face
- Triggered by heat, alcohol, spicy foods, and stress
- More common in fair-skinned adults
Clinical Presentation
- Facial flushing and persistent erythema
- Papules and pustules on cheeks, nose, and forehead
- Telangiectasias commonly present
- No comedones
- Possible ocular involvement
- Severe cases may progress to rhinophyma, especially in men
- The question stem would likely describe an adult with facial flushing worsened by alcohol or heat
Diagnostics
- Clinical diagnosis
Treatment
- Avoid known triggers
- Topical metronidazole or azelaic acid
- Oral doxycycline for inflammatory disease
- Laser therapy for telangiectasias
Exam Keys
- Acne-like lesions without comedones suggest rosacea
- Triggers such as alcohol and heat are key clues
- First-line therapy includes topical metronidazole
Rapid Differentiation — Acneiform Eruptions
- Comedones present → Acne vulgaris
- No comedones + flushing/telangiectasia → Rosacea
- Perioral papules sparing vermillion border → Perioral dermatitis
- Pustules centered on hair follicles → Folliculitis
Papulosquamous Disorders
- Group of inflammatory skin conditions defined by papules and plaques with scale
Atopic Dermatitis (Eczema)
- Chronic inflammatory skin disease associated with atopy
- Due to skin barrier dysfunction and immune dysregulation
- Common in children, but can persist into adulthood
- Triggered by dry skin, cold weather, allergens, irritants, stress, and infection
Clinical Presentation
- Pruritus is the hallmark
- Erythematous, ill-defined, scaly patches or plaques
- Flexural surfaces (antecubital and popliteal fossae)
- Lichenification with chronic scratching
- The question stem would likely describe a child with asthma and intensely itchy flexural rash
Diagnostics
- Clinical diagnosis
Treatment
- First-line: Emollients and trigger avoidance
- Topical corticosteroids for flares
- Antihistamines for itch
- Severe or refractory: topical calcineurin inhibitors
Exam Keys
- Itch + flexural eczema + atopy = atopic dermatitis
Contact Dermatitis
- Inflammatory reaction due to external exposure
- Two types: irritant and allergic
Clinical Presentation
- Well-demarcated erythema with vesicles, oozing, or scaling
- Often linear or geometric
- Pruritus common
Exam Keys
- Linear rash = contact dermatitis until proven otherwise
Drug Eruptions
- Cutaneous reaction to medications
- Most commonly morbilliform
Lichen Planus
- Immune-mediated inflammatory skin condition
- Associated with hepatitis C
Pityriasis Rosea
- Self-limited inflammatory condition
- Herald patch → Christmas tree pattern
Psoriasis
- Chronic immune-mediated inflammatory disease
- Silvery scale + extensor surfaces
Seborrheic Dermatitis
- Chronic inflammatory condition of sebaceous-rich areas
- Associated with Malassezia yeast
