Hypoluminescence microscopy of pigmented skin lesions

Since the 'renaissance' of epiluminescence microscopy (ELM), histological correlation of ELM structures has been the subject of many investigations. Direct correlation is difficult because of the methodological differences between ELM and histopathology. In order to further understand the features of pigmented skin lesions (PSLs), we studied whether hypoluminescence microscopy (HLM) had any advantages over ELM. Twenty pigmented skin lesions scheduled for surgical excision were chosen randomly for this study. After excision, the lesions were studied using standard ELM and an HLM technique. For the latter, illumination was performed from the dermal side. The HLM pattern was clearly different from that of ELM. In all lesions the 'deeper' (dermal) structures became more visible. Some structures already visible in ELM appeared more visible, particularly structures apparently localized in deeper layers of the PSL. For highly pigmented lesions the difference in the two approaches was striking. With the HLM technique details became visible, and structures which were hardly or not visible with the classic ELM approach could be easily distinguished and evaluated. In conclusion, HLM is a simple, easy to use, reproducible ex vivo technique that is able to provide additional information to the conventional ELM technique.