1. What is Body Surface Area (BSA) Calculation for Psoriasis?

Definition: This calculator estimates the percentage of body surface area affected by psoriasis using the palm method (1 palm ≈ 1% BSA).

Purpose: It helps dermatologists and patients assess psoriasis severity and track treatment progress.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \%BSA \) — Percentage of body surface area affected
• Each body region is estimated as a percentage of total BSA
• 1 palm of the patient's hand ≈ 1% of their total BSA

Explanation: The affected areas of different body parts are summed to get the total percentage of BSA affected by psoriasis.

3. Importance of BSA Calculation in Psoriasis

Details: BSA assessment helps classify psoriasis severity (mild: <3%, moderate: 3-10%, severe: >10%) and guide treatment decisions.

4. Using the Calculator

Tips: Enter the percentage affected for each body region (head, torso, arms, legs). Use the palm method (1 palm = 1%) to estimate affected areas.

5. Frequently Asked Questions (FAQ)

Q1: What is the palm method?
A: The patient's palm (including fingers) represents approximately 1% of their total body surface area.

Q2: How accurate is this method?
A: It provides a quick estimate. For precise measurement, healthcare providers may use more detailed methods like the Rule of Nines.

Q3: What body regions should I assess?
A: Typically assess head (4.5%), torso (36%), arms (9% each), legs (18% each), but adjust based on actual affected areas.

Q4: How does BSA relate to psoriasis severity?
A: Generally, <3% is mild, 3-10% moderate, >10% severe, but also consider lesion quality and impact on quality of life.

Q5: Should I include unaffected areas?
A: No, only include areas with active psoriasis lesions (red, scaly patches).