What is the Incidence of CSF Cytology Positivity?
The positivity rates of CSF cytology in patients with intracranial germinoma vary considerably (range, 0% to 100%).[15-18] The wide variation in incidence may be attributed to the fact that the majority of series have included radiographic or non-histologically verified germinomas. Table 1 shows recent reports of histologically verified germinomas and the incidence of CSF cytology positivity; the incidence varies from 7.7% to 17.6%.[18-23] There does not seem to be a higher incidence of subarachnoid seeding with suprasellar lesions.[18,19] In one study of 42 patients, 16 with a histologic and 26 with a clinical /radiologic diagnosis, the CSF cytology was positive in 52%. The authors noted that the method of detection (wet film, membrane filter cytocentrifugation, millipore filter/cell culture) may influence CSF cytology positivity, with those detected by cytocentrifugation having a higher positivity rate.