Infantile renal tumors associated with hypercalcemia. Characterization of intermediate-filament clusters

Three cases of hypercalcemic infantile renal tumors were studied to identify the proteins related to their cytoplasmic 8- to 10-nm filament clusters. Immunofluorescence microscopy, using antibodies against vimentin, cytokeratin, and actin, led to the characterization of vimentin-positive filament clusters. We discuss the possibility of a mesenchymal origin for these tumors.