Psoriasis vs. Eczema: Key Differences in Symptoms, Causes, and Treatment Approaches

Quick Comparison

Feature	Psoriasis	Eczema (Atopic Dermatitis)
Appearance	Well-demarcated, thick, silvery-scaled plaques on an erythematous base	Ill-defined, dry, excoriated, lichenified patches; may ooze or crust
Typical Locations	Extensor surfaces (elbows, knees), scalp, lower back, nails, glans penis	Flexural surfaces (antecubital, popliteal fossae), neck, face, hands
Itch Intensity	Mild to moderate (burning/stinging common)	Intense, often sleep-disturbing
Onset Age	Bimodal: 15–35 and 50–60	Childhood (85% by age 5); adult-onset possible
Pathophysiology	Autoimmune: IL-23/Th17 axis → keratinocyte hyperproliferation	Barrier defect (filaggrin) + Th2/Th22 inflammation + microbiome dysbiosis
Genetics	PSORS1 (HLA-C*06:02) major locus; >80 loci identified	FLG mutations (20–30%); multiple immune loci
Comorbidities	PsA, metabolic syndrome, CVD, depression, IBD, uveitis	Asthma, allergic rhinitis, food allergy, ichthyosis vulgaris, skin infections
First-Line Topicals	Corticosteroids, vitamin D analogs (calcipotriene), combination products	Corticosteroids, calcineurin inhibitors (tacrolimus, pimecrolimus)
Systemic/Biologic Options	Methotrexate, cyclosporine, apremilast, TNF/IL-17/IL-23 inhibitors	Dupilumab (IL-4Rα), tralokinumab, lebrikizumab, upadacitinib, abrocitinib
Phototherapy	NB-UVB, PUVA, excimer laser	NB-UVB, UVA1 (less common)
Course	Chronic, relapsing-remitting; rarely spontaneous remission	Often improves in adolescence; adult persistence variable

Diagnostic Clues

• Auspitz sign: Pinpoint bleeding after scale removal (psoriasis).
• Koebner phenomenon: New lesions at trauma sites (more common in psoriasis than eczema).
• Nail changes: Pitting, onycholysis, oil spots (psoriasis).
• Personal/family atopy: Strongly favors eczema diagnosis.

When to See a Dermatologist

• Uncertain diagnosis.
• Inadequate response to OTC hydrocortisone or moisturizers after 2 weeks.
• Widespread involvement, joint pain, eye symptoms, or significant quality-of-life impact.
• Need for systemic or biologic therapy.

Overlap Syndrome

"Psoriasiform eczema" or "eczematous psoriasis" can occur—especially in skin of color where morphology may blur. Biopsy may be needed for definitive diagnosis. Treatment often combines principles from both therapeutic algorithms.