Introduction: Photodynamic therapy for psoriasis showed promise in the early 1990s with reports of plaque clearance following topical aminolevulinic acid - photodynamic therapy (ALA-PDT).
Methods: In December 2013, we conducted a systematic search of the PubMed Medline database using the keywords "psoriasis" and "photodynamic therapy".
Results: Numerous clinical studies have failed to demonstrate a consistent, efficacious response to topical ALA-PDT. Furthermore, severe pain and burning sensations were repeatedly reported, many cases being intolerable for patients.
Discussion: The variability in clinical response and the painful side effects have made topical ALA-PDT an unsuitable treatment option for chronic plaque psoriasis. Nonetheless, early clinical studies of other modalities such as topical hypericin and methylene blue, as well as systemic ALA and verteporfin, have shown that these photosensitizers are efficacious and much better tolerated than topical ALA.
Conclusion: With the current landscape of phototherapy dominated by psoralen combined with ultraviolet A (PUVA) and narrow-band ultraviolet B (NB-UVB), an alternative light therapy utilizing the visible spectrum is certainly promising and a worthwhile endeavor to pursue.
Keywords: ALA; PpIX; aminolevulinic acid; hypericin; methylene blue; verteporfin.