Stereotaxic cytology of brain tumors. Review of an eight-year experience.

The cytologic diagnosis of 312 stereotaxic samplings performed on 292 patients suspected of having a brain tumor over an eight-year period was reviewed. At different depths of the stereotaxic track, biopsy specimens were secured for cytologic and histologic observations. Smears for cytology were stained both by the May-Grünwald-Giemsa and the Papanicolaou methods since each of them disclosed information complementary to the other. Cytology and histology were in good agreement in 87.5% of the cases. Analysis of the data revealed a cytologic sensitivity of 88.8% and a specificity of 81.9%. The main difficulty encountered was differentiating between nonspecific glial hyperplasia and low-grade astrocytoma. To a lesser degree, differentiating metastases from glioblastoma sometimes was a problem. Stress is laid on the reliability of this type of cytology, its great help when sectioning of unfit specimens makes histologic evaluation hazardous, and its obvious importance when craniotomy is not desirable but a precise pathologic diagnosis is necessary for therapeutic decision. The stereotaxic procedure is briefly reviewed, and the main cytologic findings for the principal lesions encountered are illustrated and discussed.