Kaposi's Sarcoma after Renal Transplantation

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     To the Editor: The regression of Kaposi's sarcoma in renal-graft recipients after switching from treatment with cyclosporine and mycophenolate mofetil to sirolimus, as reported by Stallone et al. (March 31 issue),1 is remarkable and confirms earlier observations.2,3 However, the immunohistochemical results in this study1 seem to be less convincing. The detection of Flk-1/KDR was reportedly performed on "acetone-fixed kidney sections," but it is clearly stated that patients had no visceral involvement. Figure 2A, Figure 2B, and Figure 2C of the article do not seem to show greatly different vascular endothelial growth factor (VEGF) expression, certainly not in the range of 5 to 60, as claimed in Figure 2D. The same reservation applies to Figure 3A through 3D with respect to Flk-1/KDR. The visual quantification of immunohistochemical staining on tissue sections in arbitrary units is not reliable, if at all feasible, since it depends largely on technical parameters that cannot be sufficiently standardized and, more important, on the number of cells expressing the antigen studied. For this reason, comparing normal skin with Kaposi's sarcoma tissue seems irrelevant.

    Jean Kanitakis, M.D.

    Edouard Herriot Hospital

    69003 Lyon, France

    kanitakis@lyon.inserm.fr

    References

    Stallone G, Schena A, Infante B, et al. Sirolimus for Kaposi's sarcoma in renal-transplant recipients. N Engl J Med 2005;352:1317-1323.

    Campistol J, Gutierrez-Dalmau A, Torregrosa JV. Conversion to sirolimus: a successful treatment for posttransplantation Kaposi's sarcoma. Transplantation 2004;77:760-762.

    http://www.100md.com/html/DirDu/2007/01/01/32/59/39.htm