Utility of squash smear cytology in intraoperative diagnosis of central nervous system tumors

Abstract

Background:Central nervous system (CNS) squash cytology (CSC) has established itself as a technically simple, rapid, inexpensive, fairly accurate, and dependable intraoperative diagnostic tool. It helps neurosurgeons immensely when management is dependent on it.Aims:This study aimed at finding out the utility of CSC as an intraoperative diagnostic tool from a neurosurgeon's perspective.Materials and Methods:Fifty prospectively registered patients with clinical diagnosis of CNS tumors were enrolled in the study. All the patients were subjected to magnetic resonance imaging (MRI). Intraoperative CSC was performed and smears were stained with Leishman and rapid Hematoxylin and Eosin (H and E) stain. The diagnosis of CSC was compared with MRI diagnosis and histopathological diagnosis. The CNS tumors were categorized based on clinical and therapeutic implications. Diagnostic accuracy, sensitivity, specificity, and positive and negative predictive value of MRI and CSC were calculated by using appropriate formulae.Results and Conclusions:The age range of the CNS tumors included in the study was 2 to 68 years. There was a slight female preponderance. Sensitivity, specificity, positive predictive value, and negative predictive value of preoperative MRI were 90.47%, 82.76%, 79.17%, and 92.31% respectively. These values of utility parameters for CSC were 100% for each of the clinical and therapeutic implications. It helped neurosurgeons in optimizing surgical procedure in 12 cases of meningioma. It influenced surgical management in 1 case of infratentorial pilocytic astrocytoma, and helped in the diagnosis and management of 9 unexpected tumors missed on MRI.

The utility of intraoperative impression smear cytology of intracranial granular cell tumors: Three cases

“…Given that histopathology can take up to 7‐14 days to be processed, other diagnostic techniques have been explored in people that could provide a more timely diagnosis. These techniques include intraoperative impression smears created via squash smear and touch imprint techniques . Performing this type of cytology is not technically demanding, and more friable tissue (such as the central nervous system) is easy to smear, often providing sufficient cellularity…”

“…In human medicine, intraoperative squash cytology is frequently used and shown to have a strong correlation with histopathologic diagnoses. Many retrospective studies performed over the past two decades have found a strong positive correlation between cytology and histology of intracranial tumors with an accuracy of 83%‐95% . A more recent study comparing cytologic and histologic diagnoses of space‐occupying central nervous system lesions revealed a diagnostic accuracy of 95% .…”

“…While there is a larger body of literature regarding the diagnostic accuracy of the squash technique, there are specific advantages in using the touch imprint technique. The squash technique has been associated with difficult preparations and subsequent misdiagnoses of tumor types . More specifically, tumors that are fibrous, such as schwannomas and some meningiomas, have been reported to be difficult to prepare via the squash technique .…”

“…More specifically, tumors that are fibrous, such as schwannomas and some meningiomas, have been reported to be difficult to prepare via the squash technique . Necrosis, as seen in many neoplastic lesions, can reduce the presence of characteristic cellular morphologies leading to misdiagnoses as well . When applying the touch imprint technique, crushing artifact and smearing difficulty can be avoided preserving cellular morphology .…”

Utility of intraoperative squash cytology in diagnosis of paediatric central nervous system lesions

“…Role of squash cytology in intraoperative diagnosis (IOD) of central nervous system (CNS) lesions has been well established. [1][2][3][4][5] Some centres use frozen section biopsy while some resort to both squash cytology and frozen section biopsy for higher diagnostic accuracy. [6][7][8][9] In resource constrained settings, often the only modality available for IOD is squash cytology.…”