Nickel-induced malignant tumors.

A series of malignant tumors experimentally induced by implanting Ni3S2 in gelatin capsules into the right hind limb of Fischer 344 rats is described. In this series, histology and ultrastructure revealed two major cell types. These are described as fibroblast-like and histiocyte-like. In addition, numerous giant cells, including large bizarre multinucleate giant cells with granular cytoplasm, were also seen. In this preliminary report, no more precise diagnosis will be given for this tumor than "malignant tumor of pluripotential origin". Further work is proposed to define more specifically its histogenesis. The appearances of the experimentally produced tumor are compared with certain tumors found in humans and also in experimentally induced tumors by Maruyama et al designated as malignant fibrous histiocytoma (MFH).