Comparison of Computer-Aided Design and Rule of Nines Methods in the Evaluation of the Extent of Body Involvement in Cutaneous Lesions

Precise determination of the area involved in cutaneous lesions is needed for an accurate therapeutic assessment of disease activity. Various methods, with their advantages and disadvantages, have been described.^1-4 We used computer-aided designing (CAD) software to determine the percentage of body area involved in the dermatoses and compared it with results of the conventional rule of nines method.

Patients and Methods.  In 45 patients (20 with psoriasis, 15 with exfoliative dermatitis [ED], and 10 with vitiligo), the percentage of body area involved was determined by both the rule of nines and CAD methods. On a 480-cm² graph sheet, the ventral (69.57-cm²) and dorsal (69.57-cm²) surface of a human figure was graphically constructed (Figure 1) on the digitizer and visualized on a monitor. Proportionate graphical representations of site, size, and shape of the cutaneous lesions were marked (Figure 2) on the CAD graph. In ED, since the skin involvemnet was generalized, the uninvolved areas were marked.