Human and experimental reticulum cell sarcoma (microglioma) of the nervous system

The histology and ultrastructure of primary central nervous system and metastatic (epidural) reticulum cell sarcoma is described. The tumors showed varying numbers of argyrophilic microglial cells which in all cases constituted a minority of all tumor cells. A primitive, undifferentiated cell, common to all tumors, was a small cell with a large dense nucleus and a narrow rim of poorly structured cytoplasm. These cells frequently showed small fatty inclusions and were tentatively identified as primitive multipotential cells from which all other tumor cells develop. It is concluded that reticulum cell sarcoma of the nervous system (primary or metastatic) and microglioma or microgliomatosis are one and the same tumor.