1. What is BSA in Psoriasis?

Body Surface Area (BSA) affected by psoriasis is a key measure of disease severity. It helps clinicians determine appropriate treatment approaches and monitor disease progression over time.

2. How to Measure BSA Using Palm Method

The palm method is a simple way to estimate BSA:

Where:

• 1 palm = approximately 1% of total body surface area
• Includes fingers and palm (entire hand excluding fingers = 0.5%)
• Use patient's own palm for most accurate estimation

Explanation: This method provides a quick, practical way to estimate psoriasis coverage without specialized tools.

3. Importance of BSA Calculation

Details: BSA assessment helps classify psoriasis severity (mild: <3%, moderate: 3-10%, severe: >10%) and guides treatment decisions including eligibility for systemic therapies.

4. Using the Calculator

Tips: Visually estimate how many of the patient's palms would cover all affected areas. Enter this number (can use decimals for partial palms).

5. Frequently Asked Questions (FAQ)

Q1: How accurate is the palm method?
A: It's an estimate (±1-2%), but sufficiently accurate for clinical decision making in most cases.

Q2: Are there more precise methods?
A: Yes, the Rule of Nines or digital imaging tools provide more precision but require more time/resources.

Q3: Does location of lesions matter?
A: Yes - lesions on face, genitals, palms/soles may warrant treatment even if <1% BSA due to significant impact.

Q4: How often should BSA be measured?
A: At each visit to monitor treatment response, typically every 3-6 months for stable patients.

Q5: Should nail psoriasis be included?
A: Nail involvement is typically recorded separately, though severe nail psoriasis may count as 1% BSA.