The extensiveness of a lesion may determine its seriousness. In burns and scalds, the importance of extent of lesion has long been recognized. Sixty-three years ago, Timothy Holmes1 said, "These injuries have been variously classified, into four divisions by Heister and Callisen, into six by Dupuytren, and various other divisions have been proposed; all of them indicating the depth of tissue implicated in the injury . . . but another, and perhaps even more important, consideration is the extent of the burnt surface—a matter which necessarily eludes formal classification."
It is indeed impossible, practically, to determine the actual extent of a lesion. But, what is of greater value, its extensiveness relative to the body surface can be readily estimated. To express such relationship, the lesion must be compared with factors in the body surface which (1) represent the total surface area of the body; (2) maintain a constant relation to each other