Recurring digital fibrous tumour of childhood: An electron microscopic and virological study

A digital fibrous tumour of the type described by Reye was examined with the electron microscope. The large cytoplasmic inclusions that constitute the distinctive histological feature of this lesion were found to comprise compact masses of granules and filaments without a limiting membrane. They closely resembled structures that have been shown to develop in the cytoplasm of cells infected with various species of viruses and that have been interpreted as virus assembly sites. However, no viral particles could be identified in the tumour and attempts to isolate viruses were unsuccessful. Crystals were frequently found in the vicinity of the granular inclusions: their significance was not clear. Bodies that bore a superficial histological resemblance to the inclusions were seen in a tissue culture of the tumour, but contamination of the culture with a yeast prevented studies that might have elucidated their nature