Smears and frozen sections in the intraoperative diagnosis of central nervous system lesions

The rapid diagnostic techniques of smears and frozen sections are fundamental to the strategy of the neuropathologist in evaluating tissue received at the time of operating room consultation with the neurosurgeon. This strategy begins with the exclusion of nonneoplastic lesions and proceeds to determination of the neoplastic cell type, or, in the case of reoperation of a treated tumor, the distinction of viable from necrotic tumor. In the interest of conserving unfrozen tissue for permanent sections, a smear may be made and examined initially, with a frozen section prepared only if the smear is equivocal or technically inadequate. This approach has been shown to result in a degree of diagnostic accuracy comparable to that described in general surgical material subject to frozen section analysis.