The majority would appear to be the result of changes in a sarcoma, endothelioma, or myeloma.
The chief of these are: simple—dermoid patches, moles of the limbus; malignant—sarcoma, endothelioma, epithelioma.
Sarcoma and endothelioma are the commonest tumours of bone, and present wide variations in structure and in clinical features.
endothelioma en·do·the·li·o·ma (ěn'dō-thē'lē-ō'mə)
n. pl. en·do·the·li·o·mas or en·do·the·li·o·ma·ta (-mə-tə)
Any of various benign or occasionally malignant neoplasms derived from the endothelial tissue of blood vessels or lymphatic channels.