Smear diagnosis of central nervous system lesions : a critical appraisal.

Smears, imprints and frozen sections have been recognised as useful adjuncts to diagnosis by the traditional paraffin section in neurosurgical biopsies. In this study, 251 intracranial space occupying lesions were studied by smears and paraffin sections to determine the causes of error and the possible means to avoid them. There were 63 computed tomography guided stereotactic microbiopsies and 188 open biopsies. The overall diagnostic accuracy was 88. In 6.8 of cases the tumour type was diagnosedcorrectly, but the grade was altered subsequent to examining the paraffin sections owing probably to sampling errors. Only 5.2 of cases had an entirely incorrect diagnosis.