Here's a confession. Dermatology was the section I dreaded most when I sat for my FNP boards. There are a thousand rashes. They all look similar in textbook photos. They all have weird Latin names. And the exam will ask you to identify them from a one-line description.
I'm going to give you the framework I built to survive this section. It's not exhaustive. It's strategic. The exam tests maybe 30 dermatologic conditions and weights about 10 of them heavily.
Derm is pattern recognition. Learn the patterns and you can answer questions you've never seen before.
The Vocabulary
You can't read a derm question without understanding the descriptors. Know these cold:
- Macule — flat, <1 cm
- Patch — flat, >1 cm
- Papule — raised, <1 cm
- Plaque — raised, >1 cm
- Nodule — raised, deeper
- Vesicle — small fluid-filled (<1 cm)
- Bulla — large fluid-filled (>1 cm)
- Pustule — pus-filled
- Wheal — transient raised area (hives)
The 10 High-Yield Conditions
1. Atopic dermatitis (eczema)
Chronic, itchy, flexural distribution in children (antecubital, popliteal), often with personal/family history of asthma and allergic rhinitis (the atopic triad). Treatment: emollients, low- to mid-potency topical steroids during flares, topical calcineurin inhibitors for face/intertriginous areas.
2. Contact dermatitis
Sharp borders following exposure pattern. Two types: irritant (more common, occurs in anyone) and allergic (Type IV hypersensitivity, sensitization required). Classic example: poison ivy (linear vesicles). Treatment: remove the offender, topical steroids, oral steroids for severe cases.
3. Psoriasis
Thick, silvery scales on erythematous base. Extensor surfaces (elbows, knees), scalp. Auspitz sign (pinpoint bleeding when scale lifted). Nail pitting. Treatment: topical steroids, calcipotriene, phototherapy, biologics for severe.
4. Acne
Comedones, papules, pustules, cysts on face/back/chest. Treatment ladder: topical retinoid + benzoyl peroxide → add topical antibiotic → add oral antibiotic (doxycycline) → consider oral contraceptives in women → isotretinoin for severe nodulocystic. Always two iPLEDGE precautions in mind for isotretinoin.
5. Rosacea
Central face erythema, telangiectasias, papules and pustules, ocular involvement. No comedones (distinguishes from acne). Treatment: topical metronidazole, ivermectin, azelaic acid, or oral doxycycline. Avoid triggers (alcohol, spicy food, sun).
6. Tinea infections
Annular lesion with central clearing and active scaly border. Confirm with KOH prep. Treatments:
- Tinea corporis, cruris, pedis — topical antifungals (terbinafine, clotrimazole)
- Tinea capitis — ORAL antifungals (griseofulvin or terbinafine). Topical alone won't work.
- Onychomycosis — oral terbinafine (check LFTs)
7. Candidiasis
Beefy red, satellite lesions, intertriginous areas. Treatment: topical nystatin, clotrimazole, or miconazole. Oral fluconazole for severe or recurrent.
8. Herpes simplex
Grouped vesicles on erythematous base. Oral or genital. Treatment: oral acyclovir, valacyclovir, or famciclovir. Initial outbreak gets longer course; recurrences shorter.
9. Herpes zoster (shingles)
Unilateral painful dermatomal vesicular rash. Treatment: antiviral within 72 hours of rash onset (valacyclovir, famciclovir). Prevention: Shingrix vaccine ≥50 years.
10. Skin cancers
- Basal cell carcinoma — pearly papule with telangiectasias, often face. Most common skin cancer. Rarely metastasizes.
- Squamous cell carcinoma — scaly red plaque, sun-exposed. Can metastasize.
- Melanoma — ABCDE (Asymmetry, Border irregular, Color varied, Diameter >6mm, Evolving). Can be deadly.
Test Pearl: The exam loves the ABCDE rule for melanoma. Memorize it word for word.
The Approach
For every derm question, ask:
- What does the lesion look like (descriptor)?
- Where is it located?
- What's the time course?
- What associated symptoms?
Those four data points usually narrow it to 2 or 3 conditions. Then pick based on best fit.
The Topical Steroid Ladder
Know which is which:
- Low potency: hydrocortisone 1% — face, intertriginous areas, children
- Mid potency: triamcinolone — body
- High potency: betamethasone, fluocinonide — palms, soles, severe flares
- Ultra-high: clobetasol — short courses only, never on face
Wrong potency on the wrong location is a common board distractor. Don't put clobetasol on a child's face.
Derm is more learnable than it looks. Drill the 10 conditions and you'll get most of the questions right.