Objective: Intraoperative crush/squash smear or frozen section consultation is routinely performed at several centers and offers rapid onsite assessment of tumor type and provides invaluable information to the neurosurgeons. The WHO classification of central nervous system neoplasms underwent a paradigm shift in 2016 with the incorporation of molecular data with the morphological features, such that several new entities came to be distinctly defined. With this paper, we present our experience at intraoperative consultation of brain tumors arising in posterior fossa and aim to apprise the pathologists with the spectrum of cytomorphologic appearances that can occur during such consultation and highlight the diagnostic dilemmas and pitfalls encountered in this setting.
Methods: This is a retrospective observational study illustrating the salient morphological features of commonly encountered brain tumors arising in the posterior fossa (prototype example of each type) reported at our institute over a period of seven years. Both squash smears and rapid snap frozen section were prepared and stained with Toluidine blue and rapid hematoxylin and eosin (H&E) stains.
Results and conclusions: While the majority of tumors at this location comprise of pilocytic astrocytoma, ependymoma, and medulloblastoma, some rare examples may also arise; common differentials must be considered and prudently excluded to arrive at the diagnosis which is crucial in guiding the neurosurgeon. Both squash smears and rapid frozen section should be prepared and complement each other for rapid on-site evaluation.
Keywords: 2016 WHO classification of CNS tumors; brain tumors; crush smear; frozen section; intraoperative Consultation.
© 2021 John Wiley & Sons Ltd.