Malignant round-cell tumours of bone: an analytical histological study from the Cancer Research Campaign's bone tumour panel.

A study of 40 cases of malignant round-cell tumour of one was made from the files of the Cancer Research Campaign's Bone Tumour Panel. Five pathologists made a careful study of observer error, involving repeated examination of routine paraffin sections, to determine whether the cases were a homogeneous group or a collection of differing sub-groups. Cell outline, nuclear staining, nuclear pleomorphism, conspicuous nucleoli, reticulin pattern and intracellular glycogen were the histological features selected for study. For each feature, the results were analysed to assess the importance of differences between tumours, between samples of tissue from the same tumour, and between observers. It is concluded that round-cell tumours of bone are a heterogeneous group, although completely distinct sub-groups could not be identified. Certain histological features tend to be associated, and it is reasonable to distinguish on histological grounds between Ewing's sarcoma and reticulum-cell sarcoma, although some tumours are not typical of either group.