A simple approach to differential diagnosis in crush preparatory brain tumor cytology

Objective: To propose a simple approach to differential diagnosing brain tumor cytology. Study Design: We reviewed crush preparatory Papanicolaoustained slides of low-grade diffuse astrocytoma, anaplastic astrocytoma, glioblastoma, pilocytic astrocytoma, oligodendroglioma, ependymoma, medulloblastoma, schwannoma, meningioma, pituitary adenoma, and metastatic tumors. Results: We classified tumors by predominant cell appearance into three groups; cell clusters, individually isolated cell patterns, and combined clusters and individual cells. Clusters were further subclassified into densely packed cell clusters or loosely grouped cells with light-green stained neural matrix. Schwannoma, meninigoma, and papillary ependymoma belonged to dense cell clusters. Benign and malignant astrocytic tumors, schwannoma of degenerated areas, and meningioma were evidenced by loosely grouped cells with a neural matrix. Oligodendroglioma, medulloblastoma, and pituitary adenoma showed individual isolated patterns. Glioblastoma, meninigoma, and metastatic tumors were of the combined type. Nuclear streaks were valuable in differential diagnosis because the great majority of neuroepithelial tumors tended to have nuclear streaks. while other tumor origins did not. The assessment of cell atypia and vascular pattern is necessary for grading astrocytic tumors. Conclusion: We highly recommend this simple, replicable approach to brain tumor cytology.