The Psoriasis Scalp Severity Index (PSSI) can be used to evaluate and monitor a patient with scalp psoriasis. It is a modification of the Psoriasis Activity and Severity Index (PASI) scoring system.
(1) type of change (erythema, induation, scaling)
(2) severity of psoriatic changes
(3) percent of scalp area involved by the change
Change in Psoriasis
Severity of Change
moderate to severe
Portion of Scalp Affected
1 - 10%
10 – 29%
30 – 49%
50 – 69%
70 – 89%
90 - 100%
= ((points for percent of scalp area with erythema) * (points for erythema severity)) + ((points for percent of scalp area with induration) * (points for induration severity)) + ((points for percent of scalp area with scaling) * (points for scaling severity))
• minimum score = 0
• maximum score = 72
• The higher the score the more severe the scalp psoriasis.
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Purpose: To evaluate a patient with scalp psoriasis using the Psoriasis Scalp Severity Index (PSSI).
Specialty: Dermatology, Immunology/Rheumatology
Objective: severity, prognosis, stage