Psoriasis Diagnosis and Management
Diagnostic Criteria
- The American Academy of Dermatology recommends that clinicians rely on a constellation of clinical features rather than Auspitz sign alone for definitive diagnosis of psoriasis 1, 2
- Classic psoriasis presents with well-demarcated, erythematous plaques with silvery scale, commonly involving the scalp, elbows, knees, and presacral region 2, 3
Treatment Selection
- The American Academy of Dermatology suggests that treatment decisions should be based on disease severity, with mild disease defined as less than 3% body surface area (BSA) affected, moderate disease defined as 3-10% BSA, and severe disease defined as more than 10% BSA 2, 3
- Treatment decisions should also consider the location of lesions, with areas such as the face, genitals, hands, feet, scalp, or intertriginous areas potentially warranting more aggressive treatment regardless of BSA 4, 3
- The impact on quality of life should also be taken into account when making treatment decisions 2, 5
Diagnostic Pitfalls
- Relying too heavily on Auspitz sign may lead to misdiagnosis or delayed diagnosis of psoriasis, and other clinical signs and the overall presentation should take precedence in the diagnostic process 1, 2
Clinical Presentation and Severity of Scalp Psoriasis
Typical Clinical Features
- Scalp psoriasis characteristically presents with sharply demarcated erythematous plaques covered by thick silvery‑white or micaceous scales, frequently extending beyond the hairline and accompanied by pruritus. 6
Morphologic Details
- Individual plaques may exhibit thick, mica‑like adherent scales on the scalp surface. 7
Epidemiology
- The scalp is one of the four most common anatomic sites affected by psoriasis, together with the elbows, knees, and presacral region. 8
Severity Assessment
- Even when scalp involvement accounts for less than 3 % of total body surface area, it can be classified as severe disease if it produces major emotional distress or intractable itching, irrespective of its limited extent. 9