From the Guidelines
Surface area calculation in Stevens-Johnson Syndrome (SJS) is typically performed using the Lund and Browder chart, which is a more precise method than the "rule of nines". In SJS, clinicians need to determine the percentage of body surface area (BSA) affected by epidermal detachment and lesions, as this calculation is crucial for diagnosis and classification, with SJS defined as involving less than 10% BSA, SJS/TEN overlap involving 10-30% BSA, and Toxic Epidermal Necrolysis (TEN) involving more than 30% BSA 1. The Lund and Browder chart takes into account the different body proportions in adults and children, with the head representing a larger percentage in children 1. Clinicians assess detached or detachable epidermis, including blisters, erosions, and areas of nikolsky sign positivity, and record the extent of erythema and epidermal detachment separately on a body map, estimating the percentage of BSA involved using the Lund and Browder chart 1. Accurate surface area assessment guides treatment decisions, fluid management, and prognosis estimation in these severe cutaneous adverse reactions.
- The rule of nines can be used as a rough estimate, but it is not as precise as the Lund and Browder chart.
- The Lund and Browder chart is preferred because it takes into account the different body proportions in adults and children.
- Clinicians should assess detached or detachable epidermis, including blisters, erosions, and areas of nikolsky sign positivity.
- The extent of erythema and epidermal detachment should be recorded separately on a body map, and the percentage of BSA involved should be estimated using the Lund and Browder chart.
- Accurate surface area assessment is crucial for diagnosis, classification, and treatment decisions in SJS and TEN, as it guides fluid management and prognosis estimation 1.
From the Research
Calculating Surface Area in Stevens-Johnson Syndrome (SJS)
To calculate the surface area affected by SJS, the following methods can be used:
- The rule of nines, although not directly mentioned in the provided studies, is a common method used to estimate the total body surface area (BSA) affected by burns or other skin conditions, including SJS 2, 3.
- The Lund and Browder chart is another method used to estimate BSA, which takes into account the different proportions of body surface area in adults and children 3.
- The study by 3 defines the difference between SJS, SJS/TEN overlap, and TEN based on the degree of skin detachment: SJS is defined as skin involvement of < 10%, TEN is defined as skin involvement of > 30%, and SJS/TEN overlap as 10-30% skin involvement.
Assessment of Skin Involvement
The assessment of skin involvement is crucial in calculating the surface area affected by SJS:
- The study by 4 reports a case of SJS-TEN overlap with 20% of the total body surface area affected.
- The study by 5 reports that deceased patients exhibited a significantly higher proportion of TEN (90% vs. 48%) and a larger epidermal detachment area (90% vs. 30% of the body surface area) compared to survivors.
Clinical Implications
The calculation of surface area affected by SJS has significant clinical implications:
- The study by 2 reports that SJS is a disease resulting in greater than 30% body surface area epidermal and mucosal desquamation, with a mortality rate of greater than 50%.
- The study by 6 reports that prompt treatment with systemic corticosteroids reduces morbidity and improves outcome of SJS patients, highlighting the importance of accurate assessment and calculation of surface area affected by SJS.