Different ultrastructural feature of keratinocytes in human malignant melanomas.

The ultrastructural feature of keratinocytes was investigated in human superficially spreading melanomas of type B. The tumor cells of these melanomas are characterized by spheroidal melanosomes and containing pheomelanins. Contrary to type A melanomas the keratinocytes show no striking transformation reaction neither in the nucleus nor in the cytoplasm although this part of the cell mostly contains abundant melanin granules surrounding the nucleus. Whether there exists a relation to the clinical course still has to be clarified.