TREATMENT OF SUPERFICIAL SKIN TUMORS WITH TOPICAL PHOTODYNAMIC THERAPY

Photodynamic therapy (PDT) is an experimental treatment modality which is based on photochemical destruction of tumour tissue by means of different sensitizers and irradiation with red light. The greatest disadvantage of systemic administration of photosensitizers (mostly porphyrins) is cutaneous photosensitization of the patient, which lasts for some months. An alternative therapeutic technique for superficial skin tumours is the topical application of sensitizers, especially 5-aminolevulinic acid (ALA). Therapeutic selectivity derives from enhanced ALA penetration across abnormal parakeratotic stratum corneum and from preferential accumulation of bioconverted protoporphyrin IX, which serves as photosensitizer in cells of epithelial origin. Two patients suffering from different epithelial tumours (superficial basal cell carcinoma, Bowen's disease) and treated with topical PDT after ALA application are reported. Both tumours showed complete remission, and up to 12 months after treatment there were no clinical or histological signs of tumour recurrence. Cosmetic results were good.