Intraoperative diagnosis of central nervous system lesions: Comparison of squash smear, touch imprint, and frozen section

Abstract

Background:Intraoperative diagnosis of central nervous system (CNS) lesions is of utmost importance for neurosurgeons to modify the approach at the time of surgery and to decide on further plan of management. The intraoperative diagnosis is challenging for neuropathologists.Aims:The study was undertaken to determine the accuracy of cytological techniques (crush smears and touch imprints), frozen sections of space occupying lesions of the CNS and compare it with histopathological diagnosis.Materials and Methods:A total of 75 specimens received intraoperatively were subjected to cytology and frozen section study.Results:Neoplastic lesions formed the major group with 62 (82.7%) cases while 13 (17.3%) were nonneoplastic. The diagnostic accuracy of “squash smears” was found to be 89.2%. “Touch imprints” showed diagnostic accuracy of 78.4%. The low accuracy of touch imprints was attributed to poor cellular yield. The diagnostic accuracy of “frozen section” was 75.7%. However, the overall diagnostic accuracy was 96%.Conclusion:We believe that the cytololgical methods and frozen sections are complimentary to each other and both should be used to improve the intraoperative diagnostic accuracy in the CNS lesion.

Intraoperative Squash and Touch Preparation Cytology of Brain Lesions Stained with H+E and Diff-Quik™: A 20-Year Retrospective Analysis and Comparative Literature Review

“…Touch/imprint preparation (TP), on the other hand, has also been utilized in intraoperative brain assessments [3,5,7,11,15,24] , though far less frequently. TP enables preservation of the cellular architecture and morphological features for subsequent histologic examination [5,11,24,27] , while avoiding the smearing or freezing artifacts of SP or FS [12,24,27] . The low cellular yield with TP can, however, lead to improper tumor grading or misdiagnoses [5,25,27] .…”

“…Various stains have been utilized for intraoperative brain cytology, such as hematoxylin and eosin (H+E) [3, 5-7, 9-12, 15, 16, 19-26] , Papanicolaou (Pap) [2-5, 7, 11, 18, 19, 26] , May-Grünwald-Giemsa (MGG) [2,4,14,19,20,23,24,26] , toluidine blue (TB) [1, 8-11, 13, 17, 24] , and Diff-Quik TM (DQ) [7,12] . Although not frequently employed to examine cytologic specimens, H+E is by far the most commonly used stain for SP/TP [3, 5-7, 9-12, 15, 16, 19-26] , as it is the most prevalent stain in FS consultations.…”

“…Although not frequently employed to examine cytologic specimens, H+E is by far the most commonly used stain for SP/TP [3, 5-7, 9-12, 15, 16, 19-26] , as it is the most prevalent stain in FS consultations. Like the Pap stain, H+E is desirable for detailed evaluation of nuclear features [2,7] as well as cytoplasmic and glial processes [24,27] . On the other hand, DQ is the most commonly employed stain in rapid onsite cytologic evaluation of all body sites [28] .…”

“…persing firmer lesions pose diagnostic challenges [15,18,20,24,27] . Touch/imprint preparation (TP), on the other hand, has also been utilized in intraoperative brain assessments [3,5,7,11,15,24] , though far less frequently.…”

Squash Smear Technique in Rapid Intraoperative Diagnosis of Non-neoplastic and Cystic Lesions of CNS

“…Deshpande et al 9 reports correct diagnosis of two cases of arachnoid cyst on squash smear cytology. Nanarng et al 12 reports missing a case of arachnoid cyst intraoperatively due to sampling error on cytology.…”