Differentiation between pigmented Spitz naevus and melanoma by digital dermoscopy and stepwise logistic discriminant analysis

Epiluminescence light microscopy (ELM) has proven useful in the diagnosis o f pigmented skin lesions (PSLs). However, in some cases this technique does not sufficiently increase the diagnostic accuracy in distinguishing pigmen ted Spitz naevi (PSNs) from melanoma. With the aim of obviating these probl ems of qualitative interpretation, methods based on the mathematical analys is of PSLs, such as digital dermoscopy analysis (DDA), have recently been d eveloped. In the present study we used a digital dermoscope (DBDermo-MIPS, Dell'Eva-Burroni) to analyse PSNs and melanomas with similar clinical and d ermoscopic features for any correlation between variables and to determine its discriminating power with respect to histological diagnosis. The 100 le sions underwent histological examination by three experienced dermatopathol ogists and were identified as PSNs (43) or melanomas (57). Thirty-six param eters were identified as possible discriminating variables and were grouped in four categories: geometry, colour, texture, and islands of colour. Stat istical analysis was used to identify the variables with the highest discri minating power. Stepwise discriminant analysis selected only four variables : entropy, minimum diameter, red lesion value and peripheral dark (the mean s of these variables were higher in melanomas than in PSNs). Thus the combi ned use of digital dermoscopy and stepwise logistic discriminant analysis m ade it possible to single out the best objective variables for distinguishi ng PSN and melanoma. (C) 2001 Lippincott Williams & Wilkins.