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

Diagnostic utility of intraoperative squash smear cytology of Intra-cranial lesions in a resource limited setup of central India

Introduction

Intraoperative squash smear cytology is a useful diagnostic tool in case of CNS lesions. In resource poor countries where frozen section is unavailable, cytology is the mainstay method in giving a rapid intraoperative diagnosis which helps Surgeons regarding the extent of excision. The current study aims to assess the feasibility and accuracy of intraoperative squash cytology in evaluation of CNS tumors. Definitive diagnosis is confirmed by histopathological examination.

Materials and methods

This retrospective observational study was carried out at Department of Neuropathology. All patients diagnosed with space occupying lesion (SOL) in CNS were enrolled in the study. Intra-operative cytological diagnosis was compared to histopathological diagnosis. WHO classification of CNS tumors 2021 was used to classify tumors.

Results

Total seventy patients with intracranial SOLs were enrolled in this study who were operated for the same and their specimens were examined. Two samples were found to be inadequate and not included in final analysis. Mean age was 38.8 ± 17.85 (SD). Male-female ratio was 1.5:1 with 41 (60.3%) males and 27 (39.7%) females. 58 had neoplastic and rest 10 had non-neoplastic lesions. Complete concordance was achieved in 61 cases (Diagnostic Accuracy-88.2%). 3 (4.4%) cases showed partial concordance and 4 (5.9%) were discordant. For detection of malignant lesions through squash smear cytology overall Sensitivity was 73.9%, Specificity-97.8%, Positive Predictive Value-94.4% and Negative Predictive Value-88%.

Conclusions

Squash smear cytology is a simple, rapid and cost-effective method relying solely on the expertise of pathologist. High diagnostic accuracy can be achieved with squash cytology by taking clinical and radiological findings into consideration.

Confounders of intraoperative frozen section pathology during glioma surgery

Although frozen section pathology (FSP) is commonly performed during surgery for glioma-suspicious lesions, confounders of accuracy are largely unknown. FSP and final diagnosis were compared in 398 surgeries for glioma-suspicious lesions. Diagnostic accuracy, risk factors for diagnostic shift from neoplastic to non-neoplastic tissue and vice versa according to the final diagnosis, and the impact on intraoperative and postoperative decision-making were analyzed. Diagnostic shift occurred in 70 cases (18%), and sensitivity, specificity, and the positive (PPV) and negative (NPV) predictive value of FSP were 82.5%, 77.8%, 99.4%, and 9.3%, respectively. No correlations between shift and patients' age and sex, sample fluorescence or volume, tumor location, correct information on the pathology form, final high- or low-grade histology, or molecular alterations were found (p > .05, each). Shift was more common after irradiation (25% vs 15%; p = .025) or chemotherapy (26% vs 15%; p = .022) than in treatment naïve cases and correlated with the type of surgery (p = .002). FSP altered intraoperative decision-making in 25 cases (6%). Postoperative shift led to repeated surgery in 12 patients (3%). In 45 cases, in which FSP and final diagnosis based on the same tissue, shift occurred in only 5 patients (11%), and sensitivity, specificity, PPV, and NPV for FSP were 77.4%, 78.6%, 88.9%, and 61.1%, respectively. No correlations between diagnostic shift and any of the analyzed variables were found (p > .05, each). Although accuracy of FSP during glioma surgery is sufficient, moderate NPV should be considered during intraoperative decision-making. While confounders are sparse, accuracy might be increased by repeated sampling. Diagnostic shift rarely alters postoperative treatment strategy.

Unveiling the potential application of intraoperative brain smear for brain tumor diagnosis in low-middle-income countries: A comprehensive systematic review

Background

Immediate intraoperative histopathological examination of tumor tissue is indispensable for a neurosurgeon to track surgical resection. A brain smear is a simple, rapid, and cost-effective technique, particularly important in the diagnosis of brain tumors. The study aims to determine the effectiveness of intraoperative brain smear in the diagnosis of brain tumors in low- and middle-income countries (LMICs), while also evaluating its sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy.

Methods

A comprehensive search of the literature was conducted using PubMed, Scopus, and Google Scholar. The retrieved articles were independently screened by two reviewers. The data was extracted, processed, and organized using Microsoft Excel.

Results

A total of 59 out of 553 articles screened were included in the final analysis. The sensitivity and specificity of the intraoperative smear of brain tumors were found to be over 90% in most studies. The PPV was consistently above 90% in 11 studies, reaching 100% in one study and the NPV varied, ranging from 63% to 100%, and the accuracy was found to be >80% in most studies. One recurrent theme in the majority of the included studies was that an intraoperative brain smear is a cost-effective, quick, accessible, and accurate method of diagnosing brain tumors, requiring minimal training and infrastructure.

Conclusion

Intraoperative brain smear is a simple, rapid, cost-effective, and highly sensitive diagnostic modality for brain tumors. It can be a viable and accessible alternative to more traditional methods such as frozen sections and can be incorporated into neurosurgical practice in LMICs as a reliable and efficient diagnostic tool.

Squash Cytology Diagnosing Plasmacytoma of Frontal Bone as First Presentation of Nonsecretory Multiple Myeloma

Plasmacytoma of bone is one of the criteria for diagnosing plasma cell myeloma (multiple myeloma). A plasmacytoma involving a frontal bone is unusual, with only few being reported so far. Also, when typical clinical presentation is absent, diagnosis is usually not suspected clinicoradiologically. We report a rare case of frontal bone plasmacytoma presenting as a lump over the forehead, the squash cytology of which gave the diagnosis of neoplastic etiology. Thus, squash cytology helped in early and definitive diagnosis in this patient, hastening meticulous diagnostic investigations and appropriate management. With full workup, the final diagnosis of a nonsecretory multiple myeloma was made.

Intraoperative cytological diagnosis of brain tumours: A preliminary study using a deep learning model

BACKGROUND

Intraoperative pathological diagnosis of central nervous system (CNS) tumours is essential to planning patient management in neuro-oncology. Frozen section slides and cytological preparations provide architectural and cellular information that is analysed by pathologists to reach an intraoperative diagnosis. Progress in the fields of artificial intelligence and machine learning means that AI systems have significant potential for the provision of highly accurate real-time diagnosis in cytopathology.

OBJECTIVE

To investigate the efficiency of machine-learning models in the intraoperative cytological diagnosis of CNS tumours.

MATERIALS AND METHODS

We trained a deep neural network to classify biopsy material for intraoperative tissue diagnosis of four major brain lesions. Overall, 205 medical images were obtained from squash smear slides of histologically correlated cases, with 18 high-grade and 11 low-grade gliomas, 17 metastatic carcinomas, and 9 non-neoplastic pathological brain tissue samples. The neural network model was trained and evaluated using 5-fold cross-validation.

RESULTS

The model achieved 95% and 97% diagnostic accuracy in the patch-level classification and patient-level classification tasks, respectively.

CONCLUSIONS

We conclude that deep learning-based classification of cytological preparations may be a promising complementary method for the rapid and accurate intraoperative diagnosis of CNS tumours.

Experimental study of different dehydration methods in the process of preparing frozen brain sections

This study aimed to provide a recommendable protocol for the preparation of brain cryosections of rats to reduce and avoid ice crystals. We have designed five different dewatering solutions (Scheme 1: dehydrate with 15%, 20%, and 30% sucrose-phosphate-buffered saline solution; Scheme 2: 20% sucrose and 30% sucrose; Scheme 3: 30% sucrose; Scheme 4: 10%, 20%, and 30% sucrose; and Scheme 5: the tissue was dehydrated with 15% and 30% sucrose polyacetate I until it sank to the bottom, followed by placement in 30% sucrose polyacetate II) to minimize the formation of ice crystals. Cryosections from different protocols were stained with Nissl staining and compared with each other by density between cells and the distance of intertissue spaces. The time required for the dehydration process from Scheme 1 to Scheme 5 was 24, 23, 24, 24, and 33 h, respectively. Density between cells gradually decreased from Scheme 1 to Scheme 5, and the distance of intertissue spaces was differentiated and irregular in different schemes according to the images of Nissl staining. We recommend the dewatering method of Scheme 4 (the brain tissues were dehydrated in 10%, 20% and 30% sucrose solution in turn until the tissue samples were completely immersed in the solution and then immersed in the next concentration solution for dehydration).

An Audit of Diagnostic Disparity between Intraoperative Frozen Section Diagnosis and Final Histopathological Diagnosis of Central Nervous System Lesions at a Tertiary Care Center

Introduction Evaluation of intraoperative squash smear and frozen section (FS) in central nervous system (CNS) neoplasms is consistently practiced for rapid assessment and has several advantages to its credence. It is an invaluable tool to ensure adequacy of tissue obtained to establish the diagnosis. Moreover, it aids in guiding the surgeon for critical decisions regarding the extent of resection. Although molecular markers have been integrated with morphology in the revised 2016 World Health Organization classification of brain tumors, precise morphological assessment still remains the foundation for the diagnosis and rapid intraoperative assessment of morphological details is equally critical and rewarding.

Objective This study aims to audit the diagnostic disparity between intraoperative diagnoses based on a combination of squash cytology and FS in cases of CNS lesions with gold standard, final diagnosis based on examination of formalin fixed paraffin embedded hematoxylin, and eosin-stained tissue sections.

Materials and Methods All intraoperative squash cytology and FS reported for CNS lesions from January 2017 to December 2020 were reviewed. The cases were categorized into three groups—group 1: when diagnosis of intraoperative diagnosis based on a combination of squash cytology and FS was same as the final histopathological diagnosis (concordant), group 2: partially concordant, and group 3: discordant cases.

Statistical Analysis Descriptive statistics was used to classify the data and diagnostic accuracy was calculated.

Results Complete concordance was present in 69.96% (191/273) cases, 20.1% (55/273) cases showed partial concordance, and 9.89% (27/273) cases were discordant with histopathological diagnosis. Out of the 27 discordant cases, misclassification of tumor type was the most common category (11 cases, 40%), followed by grading mismatch (7 cases, 25.9%), and misdiagnosis of tumor versus nontumor conditions (9 cases, 33.3%).

Conclusion Our study shows that combination of intraoperative squash cytology and FS shows a high percentage of accuracy in arriving at intraoperative diagnosis in cases of intracranial lesions. Regular audits of discordant cases should be conducted by surgeons and pathologists as part of a quality assurance measure to sensitize themselves with the potential pitfalls, minimizing misinterpretation and helping in providing a more conclusive opinion to the operating surgeons.

A comparative study of squash smear cytology diagnosis and radiological diagnosis with histopathology in central nervous system lesions

Background:

Space occupying lesions (SOLs) of central nervous system (CNS) constitutes important cause of neurological morbidity and mortality. Squash cytology is technically a simple and rapid intraoperative diagnostic tool. Radiology is supportive of histopathological diagnosis.

Objectives:

To enumerate the histopathological patterns of various central nervous system (CNS) lesions, to correlate cytopathological diagnosis with histopathological diagnosis, and to correlate radiological diagnosis with histopathological diagnosis.

Materials and Methods:

It was a retrospective study of CNS lesion cases from January 2015 to August 2018. Cytological-histopathological concordance and radiological-histopathological concordance were calculated. Chi-square test was the statistical tool used for statistical analysis.

Results:

Histopathological diagnosis of 50 cases included neoplastic lesions (42 cases [84%]) and non-neoplastic lesions (8 cases [16%]). Correct diagnosis was achieved by squash cytology in 36 cases (72%) and radiological diagnosis in 25 cases (50%) by complete concordance. However, diagnostic accuracy of squash and radiology improved considerably by 90% and 76%, respectively, after applying partial concordance criteria. For the detection of neoplastic lesions, squash cytology had 98% and radiology had 80% diagnostic efficacy.

Conclusion:

Preoperative radiological investigation and intraoperative squash smear cytology are complementary to each other. A multidisciplinary approach is necessary for the management of patients.

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.

Comparative evaluation of squash smear and frozen section in the intraoperative diagnosis of central nervous system tumours

BACKGROUND

The squash smear technique was introduced into intra-operative neurosurgical diagnosis as early as 1930. It is becoming increasingly popular in the diagnosis of central nervous system (CNS) lesions, and is fairly accurate even with a small sample. The current study assesses the accuracy and utility of the squash smear and frozen section (FS) techniques in intraoperative consultations. Correlations with histopathological diagnoses are presented.

AIMS

To compare two intra-operative diagnostic techniques-squash smear cytology and FS examination-in the context of central nervous system tumours.

MATERIALS AND METHODS

A total of 53 cases of CNS tumours were included in the study, and all were subjected to squash smear examination. FS examinations were conducted for 39 of these samples. The results of the two techniques were compared and correlated with histopathological diagnoses. The observed results were then analysed using SPSS software.

RESULTS

The most common primary CNS tumours were gliomas and meningiomas (28.3% each). The sensitivity, specificity, positive predictive value and negative predictive value for squash cytology were 86.67%, 87.5%, 81.25% and 91.3%, and for FS were 91.67%, 93.10%, 91.67%, 93.10%, respectively, with a corresponding comparative P-value of 0.56 (insignificant). Cytological diagnosis showed complete correlation with histopathological diagnosis in 39 cases (73.58%), partial correlation in eight cases (15.1%) and no correlation in six cases (11.32%). FS diagnosis showed complete correlation in 29 cases (74.35%), partial correlation in eight cases (20.5%) and no correlation in two cases (5.1%).

CONCLUSION

Squash smear is a rapid, self-sufficient and cost-effective method for the intraoperative diagnosis of CNS tumours. The squash smear and FS techniques are complementary procedures that assist the pathologist in reaching a diagnosis.

Intraoperative squash Cytology of diffuse glioma not otherwise specified, of the Cerebellum

OBJECTIVE

Diffuse glioma arises anywhere in the CNS, but most frequent in the cerebral hemispheres. The tumor tends to be seen in children and in younger adults aged 20-30. We report one such case in an older female patient presenting the intraoperative cytology of the tumor.

CASE REPORT

A 48-year-old female was diagnosed by MRI with a tumor of cerebellum. Cytologic material was obtained during the resection of the tumor and diagnosed cytologically as glioma.

CONCLUSION

This case is presented to focus the ability of the intraoperative cytology in diagnosis of the glioma, using immunocytology and confirmed by histo- immunohistology.

Diagnosis of Pituitary Adenoma Biopsies by Ultrahigh Resolution Optical Coherence Tomography Using Neuronal Networks

OBJECTIVE

Despite advancements of intraoperative visualization, the difficulty to visually distinguish adenoma from adjacent pituitary gland due to textural similarities may lead to incomplete adenoma resection or impairment of pituitary function. The aim of this study was to investigate optical coherence tomography (OCT) imaging in combination with a convolutional neural network (CNN) for objectively identify pituitary adenoma tissue in an ex vivo setting.

METHODS

A prospective study was conducted to train and test a CNN algorithm to identify pituitary adenoma tissue in OCT images of adenoma and adjacent pituitary gland samples. From each sample, 500 slices of adjacent cross-sectional OCT images were used for CNN classification.

RESULTS

OCT data acquisition was feasible in 19/20 (95%) patients. The 16.000 OCT slices of 16/19 of cases were employed for creating a trained CNN algorithm (70% for training, 15% for validating the classifier). Thereafter, the classifier was tested on the paired samples of three patients (3.000 slices). The CNN correctly predicted adenoma in the 3 adenoma samples (98%, 100% and 84% respectively), and correctly predicted gland and transition zone in the 3 samples from the adjacent pituitary gland.

CONCLUSION

Trained convolutional neural network computing has the potential for fast and objective identification of pituitary adenoma tissue in OCT images with high sensitivity ex vivo. However, further investigation with larger number of samples is required.

Nine-segment laminectomy is safe for the resection of a schwannoma extending from C-2 to T-3: a rare case report

Cervical spine schwannoma, which is long and entirely intracanal, is rare to be found. Its rarity and atypical feature leads to difficulty in diagnosing and managing cases because of the scarcity of available literature. The surgical removal of this type of schwannomas via multisegment laminectomy is a great challenge because of various risks of postoperative complications. This report describes cervical spine schwannoma that was initially was not suspected as schwannoma and was subject to surgical removal via nine-segment laminectomy. In one year after surgery, motor function returned to normal strength, no new neurological deficits occurred, and no kyphotic deformity, which is a common complication of multisegment laminectomy.

Evaluation Study of Intraoperative Cytology Smear and Frozen Section of Glioma

Objective:

Glioma is the commonest primary malignant brain tumour. Diagnosis is made based on cytology smear, frozen section and histopathological examination. Intraoperative pathological diagnosis using either cytology smear, frozen section or combination of both, plays a crucial role in patient’s future management and prognosis. This study aims to determine the accuracy of cytology smear and frozen section in glioma, and to compare the difference between both techniques.

Methods:

A cross-sectional study was conducted involving 22 cases of glioma diagnosed intraoperatively from January 2013 until August 2019 in Hospital Universiti Sains Malaysia. The selected tissues were processed for cytology smear and frozen section. The remaining tissues were proceeded for paraffin section. The diagnosis was categorized as either low-grade or high-grade glioma based on cellularity, nuclear pleomorphism, mitotic count, microvascular proliferation and necrosis. The sensitivity and specificity of frozen section and cytology smears were determined based on paraffin section being as the gold standard. The accuracy of both techniques was compared using statistical analysis.

Results:

The overall sensitivity and specificity of cytology smear were 100% and 76.9%, respectively. Meanwhile, the sensitivity and specificity of frozen section were 100% and 84.6%. There was no significant difference in diagnostic accuracy between cytology smear and frozen section in glioma (p>0.05).

Conclusion:

Cytology smears provides an alternative method for frozen section due to good cellularity and morphology on smear. Cytology smear is rapid, inexpensive, small amount of tissue requirement and less technical demand. This finding may benefit to the hospital or treatment centres where frozen section facility is unavailable.

Pre- and Intraoperative Mapping for Tumors in the Primary Motor Cortex: Decision-Making Process in Surgical Resection

BACKGROUND

 Lesions within the primary motor cortex (M1) and the corticospinal tract (CST) represent a significant surgical challenge with a delicate functional trade-off that should be integrated in the overall patient-centered treatment plan.

METHODS

 Patients with lesions within the M1 and CST with preoperative cortical and subcortical mapping (navigated transcranial magnetic stimulation [nTMS] and tractography), intraoperative mapping, and intraoperative provisional histologic information (smear with and without 5-aminolevulinic acid [5-ALA]) were included. This independently acquired information was integrated in a decision-making process model to determine the intraoperative extent of resection.

RESULTS

 A total of 10 patients (6 patients with metastatic precentral tumor; 1 patient with grade III and 2 patients with grade IV gliomas; 1 patient with precentral cavernoma) were included in the study. Most of the patients (60%) had a preoperative motor deficit. The nTMS documented M1 invasion in all cases, and in eight patients, the lesions were embedded within the CST. Overall, 70% of patients underwent gross total resection; 20% of patients underwent near-total resection of the lesions. In only one patient was no surgical resection possible after both preoperative and intraoperative mapping. Overall, 70% of patients remained stable postoperatively, and previous motor weakness improved in 20%.

CONCLUSION

 The independently acquired anatomical (anatomical MRI) and functional (nTMS and tractography) tests in patients with CST lesions provide a useful guide for resection. The inclusion of histologic information (smear with or without 5-ALA) further allows the surgical team to balance the potential functional risks within the global treatment plan. Therefore, the patient is kept at the center of the informed decision-making process.

New trends in glioma cancer therapy: Targeting Na+ /H + exchangers

Glioma is the oneof the most prevalent primarybrain tumors. There is a variety of oxidative stresses, inflammatory pathways, apoptosis signaling, and Na⁺ /H ⁺ exchangers (NHEs) involved in the pathophysiology of glioma. Previous studies have indicated a relationship between NHEs and some molecular pathways in glioma. NHEs, including NHE1, NHE5, and NHE9 affect apoptosis, tumor-associated macrophage inflammatory pathways, matrix metalloproteinases, cancer-cell growth, invasion, and migration of glioma. Also, inhibition of NHEs contributes to increased survival in animal models of glioma. Limited studies, however, have assessed the relationship between NHEs and molecular pathways in glioma. This review summarizes current knowledge and evidence regarding the relationship between NHEs and glioma, and the mechanisms involved.

Cytologic smears improve accuracy of frozen sections of ovarian tumors in the community practice settings

Background:

The ovaries can be the site for various primary tumors and also the presenting site of metastatic disease. Quick and correct intraoperative diagnosis is crucial for the patient's further management. The aim of this study was to demonstrate the advantages of the combined diagnostic method – ovarian frozen sections in conjunction with cytologic smears.

Methods:

From June 2016 to June 2017, we prospectively prepared additional two cytologic smears with Diff-Quik stain on ovarian frozen sections comprised of two hematoxylin and eosin sections. For quality assurance purposes, we compared the results of frozen section discrepancies and deferrals with those that of the previous year from June 2015 to June 2016.

Results:

With the introduction of cytologic smears to ovarian frozen sections, the number of discrepancies and deferrals combined decreased from 13.75% to 7.85%. The most benefit of smears was observed in primary ovarian malignancies.

Conclusions:

In the setting where all the members of the pathology group render cytologic evaluations routinely, smears play an important complementary role.

Accuracy of Intraoperative Examination in Central Nervous System Lesions: A Study of 133 Cases

OBJECTIVE

Intraoperative examination is a highly valuable tool for the evaluation of central nervous system (CNS) lesions, helping the neurosurgeon to determine the best surgical management. This study aimed to evaluate the accuracy and to analyze the diagnostic disagreements and pitfalls of the intraoperative examinations through correlation with the final histopathological diagnosis in CNS lesions.

STUDY DESIGN

Retrospective analysis of intraoperative examination of CNS lesions and their final diagnosis obtained during 16 consecutive years. All diagnoses were reviewed and classified according to World Health Organization (WHO) grading for CNS tumors. Squash was performed in 119 cases, while frozen section and both methods were done in 7 cases each.

RESULTS

Among the 133 intraoperative examinations considered, 114 (85.7%) presented concordance and 19 (14.3%) diagnostic disagreement when compared with subsequent histopathological examinations. The sensitivity and specificity for the detection of neoplasia in intraoperative examination was 98 and 94%, respectively. The positive and negative predictive values were 99 and 88%, respectively. The accuracy for neoplastic and nonneoplastic disease was 85.7%. Disagreements were more frequent among low-grade (WHO grades I and II) neoplasms and nonmalignant cases.

CONCLUSIONS

Our results showed good accuracy of the intraoperative assessments for diagnosis of CNS lesions, particularly in high-grade (grades III and IV) lesions and metastatic neoplasms.

Diagnostic Accuracy of Cytology Smear and Frozen Section in Glioma

Glioma is the commonest primary intracranial tumour and it has been the most predominant tumour in many studies. It accounts for 24.7% of all primary brain tumour and 74.6% of malignant brain tumour. Intraoperative diagnosis plays a crucial role in determining the patient management. Frozen section has been the established technique in providing rapid and accurate intraoperative diagnosis. However due to some disadvantages like ice crystal artefact, high expenditure and requirement of skilled technician, there is increase usage of cytology smear either replacing or supplementing frozen section technique. The aim of this review is to determine the diagnostic accuracy of cytology smear and frozen section in glioma and to see whether there is significant difference between those techniques. The overall diagnostic accuracy for frozen section in glioma ranging from 78.4% to 95% while for cytology smear, the diagnostic accuracy ranging from 50% to 100%. Based on certain literatures, no statistically difference was observed in diagnostic accuracy of cytology smear and frozen section. Thus, cytology smear provides an alternative method in establishing intraoperative diagnosis. Both cytology smear and frozen section are complimentary to each other. It is recommended to use both techniques to improve the diagnostic accuracy in addition with adequate knowledge, clinical history, neuroimaging and intraoperative findings.

Filter paper-assisted cell transfer (FaCT) technique: A novel cell-sampling technique for intraoperative diagnosis of central nervous system tumors

BACKGROUND

Intraoperative diagnosis of central nervous system (CNS) tumors provides critical guidance to surgeons in the determination of surgical resection margins and treatment. The techniques and preparations used for the intraoperative diagnosis of CNS tumors include frozen sectioning and cytologic methods (squash smear and touch imprint). Cytologic specimens, which do not have freezing artifacts, are important as an adjuvant tool to frozen sections. However, if the amount of submitted tissue samples is limited, then it is difficult to prepare both frozen sections and squash smears or touch imprint specimens from a single sample at the same time. Therefore, the objective of this study was to derive cells directly from filter paper on which tumor samples are placed.

METHODS

The authors established the filter paper-assisted cell transfer (FaCT) smear technique, in which tumor cells are transferred onto a glass slide directly from the filter paper sample spot after the biopsy is removed.

RESULTS

Cell yields and diagnostic accuracy of the FaCT smears were assessed in 40 CNS tumors. FaCT smears had ample cell numbers and well preserved cell morphology sufficient for cytologic diagnosis, even if the submitted tissues were minimal. The overall diagnostic concordance rates between frozen sections and FaCT smears were 90% and 87.5%, respectively (no significant differences). When combining FaCT smears with frozen sections, the diagnostic concordance rate rose to 92.5%.

CONCLUSIONS

The current results suggest that the FaCT smear technique is a simple and effective processing method that has significant value for intraoperative diagnosis of CNS tumors. Cancer Cytopathol 2017;125:277-282. © 2016 American Cancer Society.