Squash preparation and frozen section in intraoperative diagnosis of central nervous system tumors.

OBJECTIVE: To investigate the diagnostic accuracy of squash preparation (smears) and frozen section (FS) in the rapid intraoperative diagnosis of central nervous system (CNS) tumors. STUDY DESIGN: One hundred eighty-three CNS tumors were examined over a period of 18 months (January 1995-June 1996). All these were open biopsies, and the smear interpretation was compared with FS findings and paraffin section diagnosis. RESULTS: In 183 tumors, squash preparation was satisfactory in 156 cases (85.2%), and the diagnostic accuracy was 89.7% (140/156), The accuracy ofFS diagnosis was 90.4% (141/156). CONCLUSION: The squash smear preparation is a fairly accurate and reliable tool in the rapid intraoperative diagnosis of CNS tumors. The accuracy of this technique is nearly as good as that ofFS (P value = .9877). With the advent of stereo tactic biopsies, the pathologist may have to depend entirely upon cytologic features for a definitive diagnosis.