Fluorescence microscopy studies on ALA sensitized tissues

Fluorescence microscopy has the potential to study the spatial distribution of photosensitizers in tissue samples with cellular or subcellular resolution. A fluorescence microscope was developed to study the distribution of photosensitizer in tissue samples by acquiring fluorescence images in various spectral ranges and spatially resolved fluorescence spectra both from jdentical samples. Both methods provide complementary information, since the fluorescence images show the distribution of the sensitizers with a high spatial resolution whereas spatially resolved fluorescence spectra can identify the sensitizers and separate their fluorescence from background light emission by the spectral shape of the fluorescence. Protoporphyrin IX (PPIX) distribution induced by 5-aminolevulinic acid (ALA) was studied by fluorescence microscopy in basal cell carcinoma (BCC) and in cervical intraepithelial neoplasia (C1N). In an attempt to understand the varying success in treating BCC with topically applied ALA the PPIX distribution was studied in BCC samples of 10 patients. A strong fluorescence was observed in tumor cells as well as in epidermis, sebaceous glands, and hair follicles. The depth of PPIX sensitization of the BCCs ranged from 0.4 to 3 mm and the ratio of tumor versus epiderma