Treatment of cutaneous leishmaniasis by photodynamic therapy: Reply*1

Abstract

We read with interest the comments contained in the letter by Drs El-On, Katz, and Weinrauch regarding our report on treatment of cutaneous leishmaniasis (CL) with photodynamic therapy (PDT). Although the diagnosis of CL resting on clinical presentation and typical histology is not in doubt, we are in complete agreement that posttreatment tissue cultures could have substantiated our claim of efficacy of PDT. Comparing various parasitological methods, Mengistu et al1Mengistu G Akuffo H Fehniger T.E Negese Y Nilsen R Comparison of parasitological and immunological methods in the diagnosis of leishmaniasis in Ethiopia.Tran R Soc Trop Med Hyg. 1992; 86: 154-157Abstract Full Text PDF PubMed Scopus (28) Google Scholar found tissue cultures to be more sensitive than direct smears and histology (56%, 40%, and 37% sensitivity, respectively) in the diagnosis of CL in Ethiopia. However, Leishmania culture techniques require substantial experience to produce reliable results, they are sensitive to contamination, and the yield decreases with the age of the lesions. Our experience with PDT for CL also includes verification of clearing by direct smears: In a recent open study, we have treated a series of 11 Israeli CL patients with a total of 32 lesions.2Enk C.D Fritsch C Jonas F Nasereddin A Ingber A Jaffe C.L et al.Treatment of cutaneous leishmaniasis with photodynamic therapy.Arch Dermatol. 2003; 139: 432-434Crossref PubMed Scopus (95) Google Scholar Therapeutic endpoints were disappearance of amastigotes by direct smear, reduction of lesion size, and cosmetic outcome. All but one lesion became amastigote negative after only two treatments, at which time the mean reduction in lesion size constituted 67 %. The cosmetic results were excellent, and no relapses were noted within the 6-month follow-up period. The combined experiences from these two PDT studies are highly suggestive of the efficacy of PDT in the treatment of CL. We also agree with El-On et al that spontaneous healing or delayed effect of sodium stibogluconate given 5 months earlier, in theory, might have caused the clinical improvement; in fact, we specifically state so in the discussion. However, the cross-over design makes this possibility highly unlikely. Then again, in the hierarchy of clinical evidence, case reports rank rather low, and introduction of post-treatment tissue cultures or even the most sophisticated cross-over design will not change the fact that the true value of PDT in the treatment of CL can only be determined in future randomized controlled trials. PDT constitutes a novel and promising therapeutic modality; however, the procedure is time consuming, expensive, and requires special equipment. For these reasons PDT is probably not an option for the majority patients with CL living in endemic areas as correctly observed by El-On et al. However, for travelers returning with CL to their countries of origin in the developed world, or for immigrants to these countries like our patient, PDT might constitute a rapid and attractive therapeutic alternative that should be taken into consideration.