Bleaching of melanin before image cytometry of the DNA content of pigmented skin tumors.
OBJECTIVE
To study the effect of bleaching of melanin with KMnO4 on the results of DNA image cytometry in pigmented skin tumors.


METHODS
Image cytometry of nuclear DNA content was performed on sections from 14 melanocytic skin tumors stained with Feulgen stain both with and without prior bleaching with KMnO4.


RESULTS
The nuclear staining intensity of Feulgen stain was lower in the bleached sections, but this did not significantly affect the evaluation of ploidy. Heavy pigmentation caused some false peaks in the histograms (4 of 28 measurements made on unbleached slides).


CONCLUSIONS
Bleaching of sections with KMnO4 can be useful when heavy melanin pigmentation would make DNA measurements impossible or difficult in image analysis cytometry. Bleaching is not advisable when only lightly pigmented tumors are analyzed if nuclei obscured by any pigment granules are to be avoided. In large series containing both bleached and nonbleached specimens, statistical analysis of these groups should be separated.
Department of Pathology, University of Turku, Finland.
L A
LA
Talve
Y U
YU
Collan
K A
KA
Alanen
D004273:DNA, Neoplasm / Q000032:analysis*; D006801:Humans; D019044:Image Cytometry / Q000379:methods; D008543:Melanins; D008545:Melanoma / Q000235:genetics / Q000473:pathology*; D012878:Skin Neoplasms / Q000235:genetics / Q000473:pathology*; D013194:Staining and Labeling
D004273:DNA, Neoplasm; D008543:Melanins