Cell culture of infantile digital fibromatosis.

Two cell cultures were obtained from excised tumors of two cases of infantile digital fibromatosis (IDF). The cells had eosinophilic cytoplasmic inclusion bodies characteristic of IDF. Although the rate of cells bearing the inclusion bodies was high at the earlier passage levels, it was reduced to zero by the 15th passage of one of the cultures, but the cells of the other culture continued to produce the inclusion bodies even at the 30th passage. Chromosome analysis revealed both cultures to have tetraploid cells in approximately 8 to 12% in late passage levels. No viruslike particles were found in electron microscopy. No tumors developed when the cells were inoculated into athymic, nude mice subcutaneously. These cell cultures will be valuable for characterizing the eosinophilic inclusion bodies and determining the origin of the tumors.