Cytologic features of the normal pineal gland on squash preparations

Intraoperative Diagnosis of Central Nervous System Tumors: Challenges, Errors, Lessons Learned, and the Surgeon's Perspective

Background: Intraoperative crush smear is an adjuvant in diagnosing central nervous system (CNS) lesions on tissue sent for frozen section. Besides rapid decision-making, it also ensures that minimum injury is caused to the normal brain structures surrounding the intracranial neoplasm. A rapid intraoperative diagnosis helps the surgeon in planning the appropriate surgery.

Objective: Our objective is to review all the discordant cases between intraoperative and histopathological diagnosis and also to study the crush smear slides for morphological clues that could have been helpful in minimizing such errors, especially for an inexperienced neuropathologist/general pathologist. The surgeon’s perspective on the impact of these errors on management is also discussed.

Method: A prospective study of six years from 2013 to 2019 was conducted. Crush smears were made and stained with rapid hematoxylin and eosin (H&E). The rest of the tissue was processed for permanent tissue sections. Slides in which there was discordance between the intraoperative and permanent paraffin sections were reviewed to ascertain the reasons thereof.

Results: A total of 81 specimens of CNS tumors were sent for intraoperative consultation. Out of these, discordance was seen in 13 (16%) cases.

Conclusion: To minimize diagnostic errors, it is important to do regular analyses of the misinterpreted cases. Knowledge of the pre-operative radiological differential diagnosis is mandatory. Discussion with the surgeon regarding the clinical impact of the errors made will give a clearer picture to the pathologists regarding clinically relevant reporting during intraoperative consultation.

Cytologic Features of Ventricular Tumors of the Central Nervous System: A Review with Emphasis on Diff-Quik Stained Smears

BACKGROUND

Neoplasms from the ventricular system share a common location but have highly variable histogenesis. Many are slowly growing tumors that behave in a benign fashion. They can be classified as primary and secondary tumors. The most common primary tumors are ependymomas, subependymomas, subependymal giant cell astrocytomas, central neurocytomas, choroid plexus tumors, meningiomas, germinomas, pineal parenchymal tumors, papillary tumors of the pineal region, chordoid gliomas, rosette-forming glioneuronal tumors of the fourth ventricle, and craniopharyngiomas. Pilocytic astrocytomas, medulloblastomas, and atypical teratoid/rhabdoid tumors often show secondary involvement of the ventricular system.

SUMMARY

Advances in neurosurgery have facilitated access to the ventricular system increasing the number of cases in which such tumors can be biopsied. In this context, cytology has been proven to be an extremely useful diagnostic tool during intraoperative pathologic consultations. Many ventricular tumors are infrequent, and the cytologic information available is limited. In this review, we describe the cytologic features of the uncommon ventricular tumors and report on unusual findings of the more common ones. For the cytologic evaluation of brain tumors, many neuropathologists prefer formalin fixation and hematoxylin and eosin staining. In this review, we highlight the cytologic findings as seen with Diff-Quik, a very popular staining method among cytopathologists. In fact, when pathologists are unfamiliar with cytology, it is common to request the assistance of cytopathologists during the evaluation of intraoperative procedures. Key Message: Ventricular tumors of the central nervous system comprise a group of heterogeneous tumors with very different cytologic features. The cytomorphology of these tumors, including rare entities, is often very characteristic, allowing a precise recognition during intraoperative pathologic consultations. Diff-Quik is a valuable staining method that can be used alone or as a complement to hematoxylin and eosin staining. Diff-Quik allows for clear visualization of the overall architecture, cytoplasmic details, and extracellular material.

Cytologic features of the normal pineal gland of adults

It is well known that the histology of normal pineal gland may resemble not only pineal tumors but also gliomas, owing to its cellularity which is much greater than that of normal white or gray matter. Our recent experience with a case in which part of a normal gland was submitted for intraoperative consultation, together with the scarcity of cytologic descriptions, led us to perform a cyto-histologic correlation study. In addition to the intraoperative case, we collected five pineal glands from consecutive adult autopsies. During the squash procedure, we often noted the presence of calcified grains. Smears were hypercellular, distributed in tissue fibrillary fragments and as numerous single cells, with crystalline structures. Pineal gland cells (pineocytes) were large, round, epithelioid with ill-defined cytoplasms and moderate nuclear pleomorphism. Spindle cells with greater fibrillary quality were less common. One of the most remarkable findings seen in all cases was the presence of cytoplasmic pigment. Histological evaluation and immunohistochemical staining confirmed that the tissue was normal pineal gland. The histology showed a characteristic lobular aspect and frequent corpora arenacea. The pigment seen cytologically was also encountered in histology and corresponded to lipofuscin. Cytologic features of the pineal gland are peculiar when compared to other normal structures of the central nervous system. These features correlate closely with what is seen on histology. In an adequate clinical context, and in combination with frozen sections, cytology allows a specific recognition of the pineal gland during intraoperative pathologic consultations.