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J Cytol
J Cytol
JCytol
J Cytol
Journal of Cytology
0970-9371
0974-5165
Wolters Kluwer - Medknow India

JCytol-41-181
10.4103/joc.joc_78_23
Images in Cytopathology
Central Neurocytoma Diagnosis on Squash Cytology
Gupta Shruti 1
Kumar Arvind 2
Kumari Niraj 1
Rajwanshi Arvind 3
1 Department of Pathology and Lab Medicine, All India Institute of Medical Sciences, Rae Bareli, Uttar Pradesh, India
2 Department of Neurosurgery, All India Institute of Medical Sciences, Rae Bareli, Uttar Pradesh, India
3 Executive Director, All India Institute of Medical Sciences, Rae Bareli, Uttar Pradesh, India
Address for correspondence: Dr. Shruti Gupta, Department of Pathology and Lab Medicine, All India Institute of Medical Sciences, Rae Bareli, Uttar Pradesh, India. E-mail: drshrutimlb@gmail.com
Jul-Sep 2024
18 7 2024
41 3 181182
22 5 2023
11 10 2023
03 6 2024
Copyright: © 2024 Journal of Cytology | Indian Academy of Cytologists
2024
https://creativecommons.org/licenses/by-nc-sa/4.0/ This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.
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pmcINTRODUCTION

Intraoperative squash diagnosis is a useful adjunct for the diagnosis of central nervous system tumors. Central neurocytomas (CNs) are rare neuronal tumors occurring frequently among young adults. The awareness of distinct cytomorphologic features of this rare entity can reliably distinguish between other glioneuronal tumors. We report a case of CN diagnosed on squash cytology and confirmed on histopathology.

CASE HISTORY

A 28-year-old male presented with headache, gradually decreasing vision in both eyes over a year, and difficulty in walking. On detailed clinical examination, pupils were dilated and there was no perception of light in both eyes. All other higher mental functions and cranial nerve examination were within normal limits. MRI of the brain revealed a large intraventricular lesion with post-contrast enhancement and hydrocephalous [Figure 1]. Surgical resection is the treatment of choice; therefore, left frontotemporal craniotomy with excision of tumor was done. Intraoperatively, the tumor was large, firm in consistency, greyish-red in color, moderately vascular, and suckable. Intraoperative squash was requested. Tiny whitish firm tissue bits received were readily squashable. Rapid hematoxylin and eosin stain (H and E) was performed. The squash cytology smears were cellular and showed groups and clusters of monomorphic tumor cells arranged around capillary channels. The individual tumor cells were round-to-oval with finely granular stippled chromatin, inconspicuous nucleoli and moderate amount of cytoplasm. A preliminary diagnosis of CN was made [Figure 1b and c]. The residual tumor tissue was sent for histopathology. Sections showed a richly vascular tumor having uniform-appearing cells with oval nuclei, stippled chromatin and clear-to-eosinophilic cytoplasm. The diagnosis of CN was confirmed on histopathology [Figure 1d and e].

Figure 1 (a) Magnetic resonance imaging scan of the brain showing heterogeneously enhancing mass in the lateral ventricle centered on the septum pellucidum. Microphotograph panel showing (b) Squash cytology cellular smear showing tumor cells in a thin wispy background arranged around thin capillary channels (c) monomorphic tumor cells with round to oval nuclei having finely granular chromatin, inconspicuous nucleoli and moderate amount of cytoplasm. (d and e) Histopathology sections showing uniform appearing tumour cells with fine stippled chromatin, inconspicuous nucleoli, surrounded by long thin walled capillary sized vessels. (b) HE, 10× (c-d) HE, 20× (e) HE, 40×

DISCUSSION

Intraoperative squash preparations are being extensively used by neurosurgeons for confirmation of preoperative and intraoperative diagnoses and assessment of margin status reliably and rapidly. Squash preparations require minimal equipment and very tiny bits of tissue but a learning curve for accurate identification.[1] CNs are rare intracranial tumors showing neuronal differentiation and excellent prognosis. Most of them are intraventricular in location with characteristic radiological appearance, with the closest radiological differential being oligodendroglioma.[2]

The cytology of CN on squash preparation smears have been described sparsely in the literature. Squash smears also often resemble oligodendrogliomas and clear cell ependymoma.[3] Cytological differential diagnoses include ependymomas, oligodendroglioma, and non-Hodgkin lymphoma. A clinic-radiological correlation and minute observations can aid in accurate diagnosis.

The presence of thin fibrillary neuropil-like eosinophilic material supports the diagnosis of CN, while the presence of less fibrillary, vacuolated background due to perinuclear clearing warrants the diagnosis of oligodendroglial lesions. The presence of pseudo rosettes-like structures can lead to a differential diagnosis of ependymoma; however, the lack of fibrillary processes around the capillaries surrounded by tumor cells supports the diagnosis of CN. The absence of lymphoglandular bodies and fibrillary background can reliably rule out the possibility of lymphoma.

On histopathology, most of these tumors have the characteristic appearance of rounded medium-sized cells with finely stippled chromatin, inconspicuous nucleoli, along with scant cytoplasm, surrounded by long thin-walled capillary-sized vessels.[4]

Immunohistochemical studies have shown CNs are immunopositive for synaptophysin, NeuN, and neuron-specific enolase. Oligodendrogliomas, on the contrary, are negative for neuronal markers and show immunopositivity for Olig2. However, due to resource constraints, immunochemistry was not performed in the index case.

An accurate intraoperative squash cytology diagnosis can be made by close correlation of radiological findings and awareness of typical cytomorphological features showing monotonous cells with finely granular stippled chromatin and ill-defined cytoplasm.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.
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