Selectivity of protoporphyrin IX fluorescence for condylomata after topical application of 5-aminolaevulinic acid: implications for photodynamic treatment

To examine the potential of using photodynamic therapy (PDT) in condylomata, we studied the distribution and kinetics of protoporphyrin IX (PpIX) formation in condylomata acuminata and adjacent normal skin after topical application of 5-aminolaevulinic acid (ALA). PpIX fluorescence spectra were measured hourly in vivo after ALA application. After gross fluorescence imaging, the lesions were biopsied, and fluorescence microscopy was performed. All three PpIX fluorescence detection modalities suggested selectivity of PpIX formation in condylomata after topical ALA application. In 17 of 25 condylomata, there was significantly greater fluorescence compared with adjacent normal skin. The greatest lesional to normal skin fluorescence ratios occurred after 2 h. The most likely mechanism for increased lesional PpIX formation in condylomata is enhanced stratum corneum permeability. Based on our results, ALA/PDT is a potential field therapy for condylomata. PpIX fluorescence imaging after ALA application may also be useful for localizing condylomata prior to treatment.