Eczema vs Psoriasis
How to tell Eczema and Psoriasis apart when a board question makes them look alike.
Step 2 CK pairs are in open beta while clinical review finishes. Spot an issue? Tell us.
Flexural intensely pruritic dermatitis favors eczema, while extensor sharply demarcated silvery plaques favor psoriasis.
Side by side
Pruritic erythematous patches on flexural surfaces with atopic history and lichenification from chronic scratching.
Well-demarcated erythematous plaques with thick silvery scale on extensor surfaces or scalp, sometimes with nail pitting.
Eczema reflects epidermal barrier dysfunction and type 2 immune inflammation causing xerosis and itch-driven dermatitis.
Psoriasis is an immune-mediated keratinocyte hyperproliferative disorder with IL-23 and IL-17 pathway activation.
Diagnosis is clinical; eosinophilia or elevated total IgE may coexist in atopic patients, and secondary infection is suggested by honey crusting or culture-positive impetiginization.
Diagnosis is clinical; plaques are sharply circumscribed with scale, and biopsy when uncertain shows parakeratosis, acanthosis, and neutrophils in stratum corneum (Munro microabscesses).
The trap
Chronic hand eczema with fissuring is often mistaken for plaque psoriasis, leading to undertreatment of itch and barrier injury. Distribution pattern and heavy adherent scale with nail pitting point toward psoriasis.
The repair move
Next best step: classify by distribution and scale pattern, then treat eczema flares with medium-potency topical corticosteroid such as triamcinolone 0.1% ointment twice daily for 1 to 2 weeks plus daily emollients. If psoriasis is present, use high-potency topical steroid such as clobetasol 0.05% twice daily for up to 2 weeks on plaques and escalate to vitamin D analogs or phototherapy for extensive disease.
Try a free question
CoreA 34-year-old man has chronic plaques over both elbows and knees. BP 122/78 mm Hg, HR 72/min, temp 36.5 C. Exam shows sharply demarcated erythematous lesions with thick silvery scale and nail pitting. What is the most likely diagnosis?
Show answer and explanation
Answer: B. Psoriasis. Extensor silvery plaques with nail pitting are classic for psoriasis.
Why the other choices are tempting
- A. Atopic eczema usually favors flexural areas with less sharply demarcated scaling plaques.
- C. Tinea corporis usually has annular lesions with central clearing and positive fungal prep.
- D. Seborrheic dermatitis favors scalp, eyebrows, and nasolabial folds with greasy scale.
- E. Lichen planus classically has violaceous polygonal papules and Wickham striae.
Flashcards
Tap a card to flip it.
Which body-site pattern most strongly supports atopic eczema in adults?
Flexural involvement of antecubital and popliteal fossae with intense pruritus supports eczema.
Which lesion feature points toward plaque psoriasis?
Sharply bordered erythematous plaques with thick silvery scale on extensor surfaces point toward psoriasis.
Quick answers
What is the fastest way to tell Eczema from Psoriasis?
Flexural intensely pruritic dermatitis favors eczema, while extensor sharply demarcated silvery plaques favor psoriasis.
What is the key clue for Eczema?
Pruritic erythematous patches on flexural surfaces with atopic history and lichenification from chronic scratching.
What is the key clue for Psoriasis?
Well-demarcated erythematous plaques with thick silvery scale on extensor surfaces or scalp, sometimes with nail pitting.
What is the common trap with Eczema vs Psoriasis?
Chronic hand eczema with fissuring is often mistaken for plaque psoriasis, leading to undertreatment of itch and barrier injury. Distribution pattern and heavy adherent scale with nail pitting point toward psoriasis.