1. What is BSA in Psoriasis?

Body Surface Area (BSA) assessment is a crucial measure in psoriasis to determine disease severity and guide treatment decisions. The palm method (1 palm = 1% BSA) is a simple, practical way to estimate affected area.

2. How Does the Calculator Work?

The calculator uses the palm method:

Where:

• 1 palm = approximately 1% of total body surface area
• Patient's own palm (excluding fingers) is used as reference

Explanation: This method provides a quick visual estimation of psoriasis coverage by comparing affected areas to the size of the patient's palm.

3. Importance of BSA Measurement

Details: BSA assessment helps classify psoriasis severity:

• Mild: <3% BSA
• Moderate: 3-10% BSA
• Severe: >10% BSA

This classification guides treatment selection and monitors disease progression.

4. Using the Calculator

Tips:

• Examine all body areas systematically
• Count how many palm-sized areas are affected
• For smaller areas, estimate fractions of a palm
• For larger contiguous areas, mentally divide into palm-sized units

5. Frequently Asked Questions (FAQ)

Q1: How accurate is the palm method?
A: It provides a good clinical estimate (±1-2%) for most patients when performed carefully.

Q2: Should fingernails be included?
A: Nail psoriasis should be assessed separately as it doesn't contribute significantly to BSA but affects severity grading.

Q3: How does this compare to the Rule of Nines?
A: The palm method is more precise for psoriasis as it allows for scattered lesions, while Rule of Nines is better for large burns.

Q4: When should more precise methods be used?
A: In clinical trials, more precise methods like PASI scoring or digital imaging may be used, but palm method suffices for routine care.

Q5: How often should BSA be reassessed?
A: At each follow-up visit (typically every 3-6 months) or when changing treatments.