Use of cytological preparations for the intraoperative diagnosis of stereotactically obtained brain biopsies: a 19-year experience and survey of neuropathologists

Object. The goals of this study were to analyze the accuracy of cytological techniques, consisting of touch and smear preparations, for the intraopera tive diagnosis of stereotactically obtained brain biopsy samples, and to de termine the prevalence of the use of these methods among neuropathologists. Methods. A survey regarding preferred methods for intraoperative diagnosis of stereotactically obtained brain biopsy samples was completed by 92 (62%) of 148 neuropathologists. Twenty-three percent of respondents chose frozen -section examination alone; 13% chose one or more cytological methods alone ; and the remainder (64%) chose a combination of frozen-section examination and cytology. At the University of Pittsburgh, the neuropathology records for all stereot actic brain biopsies performed from May 1979 through May 1998 were retrospe ctively reviewed. Of the 946 stereotactic brain biopsies, 316 cases were ex cluded because the intraoperative neuropathological consultation was not re corded. Thirty-five cases were excluded because frozen-section examinations were performed. Therefore, a total of 595 cases were suitable for analysis . Intraoperative cytological investigation correlated with the final diagnosi s in 90% of cases (52% complete correlation and 38% partial correlation). I n 11% of cases there was no correlation between the intraoperative and fina l diagnoses. Intraoperative diagnoses were most accurate in cases of absces s, germinoma, lymphoma, metastasis, and malignant glioma. Overall, 91% of biopsy specimens were diagnostic when examined using the pa raffin-embedded section technique. The sensitivity of cytological preparati ons in detecting a diagnostic specimen was 96% and the specificity in detec ting a nondiagnostic specimen was 75%. Conclusions. Intraoperative cytological preparations correlated with the fi nal diagnoses in 90% of stereotactic biopsies and had a 96% sensitivity in detecting diagnostic specimens. The highest rate of correlation was noted i n cases of abscess, germinoma, lymphoma, metastasis, and malignant glial tu mor.