Where a leptomeningeal carcinomatosis is clinically diagnosed, evidenc
e should be provided of tumor cells in the CSF. Not necessarily in the
first specimen, but in the course of the illness. The staining of the
cells with the Pappenheim method generally provides sufficient inform
ation about the cells. The identification of cells in metastases of ep
ithelial tumours is not difficult for anyone with some experience. Ide
ntifying cells from primary brain tumours - which however only rarely
cause meningosis - can sometimes be more difficult. Attention should b
e paid to whether the cells occur in clusters or singly. However, extr
eme caution is called for. The cytological monitoring of the CSF is an
essential part of chemotherapy or radiation treatment.