1. What is a BSA Calculator for Psoriasis?

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

Purpose: It helps dermatologists and patients quantify psoriasis severity by measuring skin involvement.

2. How Does the Calculator Work?

The calculator uses the palm method:

Where:

• \( \%BSA \) — Percentage of body surface area affected
• 1 palm — Approximately equals 1% of total body surface area

Explanation: The patient's palm (including fingers) represents about 1% of their total body surface area. The affected areas are estimated by counting how many palm-sized areas are covered by psoriasis.

3. Importance of BSA Calculation in Psoriasis

Details: BSA assessment helps determine disease severity, guide treatment decisions, and monitor treatment response over time.

4. Using the Calculator

Tips: Enter the number of palm-sized areas affected by psoriasis. The result shows the estimated percentage of total body surface area involved.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is the palm method?
A: While not exact, it provides a quick clinical estimate. One palm (including fingers) equals about 1% of total BSA for adults.

Q2: What's considered mild, moderate, and severe psoriasis by BSA?
A: Generally: <3% = mild, 3-10% = moderate, >10% = severe, though other factors also contribute to severity assessment.

Q3: How does this differ for children?
A: Children have different body proportions; their palms represent a slightly higher percentage of total BSA.

Q4: Should I include non-psoriatic skin in the count?
A: No, only count areas with active psoriasis lesions.

Q5: What if lesions are smaller than a palm?
A: Combine smaller lesions to estimate palm-equivalent areas (e.g., five nickel-sized lesions ≈ 1 palm).