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 di fferent sensitizers and irradiation with red light. The greatest disad vantage of systemic administration of photosensitizers (mostly porphyr ins) is cutaneous photosensitization of the patient, which lasts for s ome months. An alternative therapeutic technique for superficial skin tumours is the topical application of sensitizers, especially 5-aminol evulinic acid (ALA). Therapeutic selectivity derives from enhanced ALA penetration across abnormal parakeratotic stratum corneum and from pr eferential accumulation of bioconverted protoporphyrin IX, which serve s as photosensitizer in cells of epithelial origin. Two patients suffe ring from different epithelial tumours (superficial basal cell carcino ma, Bowen's disease) and treated with topical PDT after ALA applicatio n are reported. Both tumours showed complete remission, and up to 12 m onths after treatment there were no clinical or histological signs of tumour recurrence. Cosmetic results were good.