The Dermal-Epidermal Junction (DEJ) is a 2D surface separating the epidermis from the dermis which undergoes multiple changes under pathological or ageing conditions. Recent advances in reflectance confocal microscopy now enables the extraction of the DEJ from in-vivo imaging. This articles proposes a method to automatically analyse DEJ surfaces using self-dual morphological filters. We use self-dual pattern spectra with non-increasing attributes and we propose a novel measure in order to characterize the evolution of the surface under the filtering process. The proposed method is assessed on a specifically constituted dataset and we show that the proposed surface feature significantly correlates with both chronological ageing and photo-ageing.