Physical Examination Findings in Psoriasis
Psoriasis classically presents with well-demarcated, red plaques with silvery scale, commonly involving the scalp, elbows, knees, and presacral region, though any area of skin may be involved, including the palms, soles, nails, and genitalia. 1
Classic Plaque Psoriasis (Psoriasis Vulgaris)
- Morphology: Erythematous, well-circumscribed plaques
- Scale: Silvery-white, dry scale that may reveal pinpoint bleeding when removed (Auspitz sign)
- Distribution: Symmetrical involvement of:
- Extensor surfaces (elbows, knees)
- Scalp
- Lumbosacral area
- Umbilical region
- Back
Variant Forms of Psoriasis
Inverse Psoriasis
- Location: Skin folds (axillary, genital, perineal, intergluteal, inframammary areas)
- Appearance: Erythematous plaques with minimal scale due to moisture in these areas 1
- Special feature: May lack the characteristic scaling of typical psoriasis
Guttate Psoriasis
- Morphology: Dew-drop-like, 1-10mm, salmon-pink papules with fine scale
- Distribution: Primarily on trunk and proximal extremities
- Demographics: Common in individuals younger than 30 years 1
Pustular Psoriasis
- Appearance: Collections of neutrophils large enough to be clinically apparent as pustules
- Variants:
- Generalized (von Zumbusch): Widespread pustules on erythematous background with fever and toxicity
- Localized: Typically on palms and soles 1
Erythrodermic Psoriasis
- Appearance: Generalized erythema covering nearly the entire body surface area
- Scale: Variable degrees of scaling
- Systemic features: May include chills, hypothermia, dehydration, fever, and malaise 1
Special Sites
Nail Psoriasis
- Prevalence: Occurs in approximately 50% of patients with fingernails and 35% with toenails
- Features: Pitting, onycholysis, subungual hyperkeratosis, and oil-drop sign
- Association: Up to 90% of patients with psoriatic arthritis may have nail changes 1
Scalp Psoriasis
- Appearance: Well-defined plaques with thick, adherent scale
- Distribution: Can extend beyond the hairline onto forehead, ears, and neck
Severity Assessment
The severity of psoriasis is defined by:
Body Surface Area (BSA):
- Mild: <3% BSA
- Moderate: 3-10% BSA
- Severe: >10% BSA 1
Psoriasis Area Severity Index (PASI): Quantifies:
- Body surface area involvement
- Intensity of redness
- Scaling
- Plaque thickness
- Score ranges from 0 (no disease) to 72 (maximal severity) 1
Important Clinical Considerations
Psoriasis can be severe regardless of BSA when it:
- Has serious emotional consequences
- Occurs in sensitive locations (hands, feet, scalp, face, genital area)
- Causes intractable pruritus 1
Associated findings: May include psoriatic arthritis (25-30% of patients), which presents with:
- Joint pain, swelling, and tenderness
- Morning stiffness
- Dactylitis ("sausage digits")
- Enthesitis (inflammation at tendon/ligament insertion sites) 1
Differential Diagnosis Considerations
When examining potential psoriasis, look for the characteristic circular, well-circumscribed, red papules or plaques with grey or silvery-white dry scale that distinguishes it from other erythematosquamous conditions 2, 3.