Intraoperative diagnostic techniques for stereotactic brain biopsy: cytology versus frozen-section histopathology.

Stereotactic brain biopsy has gained widespread acceptance as a primary diagnostic tool for the evaluation of intracranial lesions. Intraoperative evaluation of such specimens has included the use of both cytological and frozen section histologic techniques. The current study seeks to compare the diagnostic utility of frozen section histopathology and cytology in the intraoperative evaluation of stereotactic brain biopsies in HIV-seropositive patients. Seventy-five HIV-seropositive patients undergoing stereotactic brain biopsy for the evaluation of intracranial lesions were evaluated; intracranial diseases were predominantly infectious or hematologic malignancies. Comparison of frozen section and cytology as a means of intraoperative evaluation showed cytology to have a greater sensitivity (86 vs. 78%), positive (95 vs. 90%) and negative (50 vs. 39%) predictive values and a greater overall diagnostic efficiency (84 vs. 75%) than frozen section. Thus, cytology is a highly effective tool equaling and in some cases surpassing frozen section in terms of sensitivity, predictive value, and overall accuracy. Cytologic examination may often be used as the sole means of intraoperative diagnosis, obviating the need for the freezing and sectioning of fresh tissue and potentially reducing specimen turn around time as well. In other cases, cytology can be used in conjunction with other methodologies for arriving at both intraoperative and final diagnoses in these often difficult cases.