An apparatus is described, for the characterisation of pigmented skin lesions, which includes an instrument for the acquisition of a plurality of images of the lesion, filmed with lighting at different wavelengths, a device designed to segment and parameterise each of the images, a device designed to extrapolate a data set from the images and input the data set into a neural network system, a device designed to compare the results processed by the neural network with the results obtained following similar processing of known cases, and a device designed to vary the weighting of each parameter supplied to the neural network on the basis of the results.