A 52-year-old woman presented with a solid spindle cell primary tumor of the lymph node. On light microscopic examination, mitoses and cellular atypia were absent. Electron-microscopic studies showed endothelial cell differentiation. Intracytoplasmic localization of Factor VIII-related antigen was demonstrated by the immunoperoxidase method, which confirmed the endothelial origin of the tumor. Seven-and-a-half years after the resection of this tumor, the patient is alive with no evidence of disease.