Cytomorphologic and Cytodiagnostic Study of Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration specimens obtained from patients undergoing diagnostic Endobronchial Ultrasound for Mediastinal and Pulmonary Lesion

Cytomorphologic and Cytodiagnostic Study of Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration specimens obtained from patients undergoing diagnostic Endobronchial Ultrasound for Mediastinal and Pulmonary Lesion

Ratan Shah*1, Sairil Pokhrel2, Deebya Raj Mishra3, Paricha Upadhyaya4, Dipti Shrestha5, Suman Pakhrin6, Ashish Paudel7 

1,7. Department of Pathology, National Medical College and Teaching Hospital, Birgunj, Nepal.

2,4,5,6. Department of Pathology, BP Koirala Institute of Health Science, Dharan, Nepal.

3. Department of Pulmonary Critical Care & Sleep Medicine, BP Koirala Institute of Health Science, Dharan, Nepal.

*Correspondence to: Ratan Shah, Department of Pathology, National Medical College and Teaching Hospital, Birgunj,  Nepal.

Copyright

© 2024 Ratan Shah. This is an open access article distributed under the Creative Commons Attribution  License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: 23 January 2024

Published: 06 February 2024

DOI: https://doi.org/10.5281/zenodo.10622882

Abstract

Background: Endobronchial ultrasound-guided transbronchial needle aspiration is a relatively new modality for sampling mediastinal and lung lesions. The cytological material obtained from patients undergoing diagnostic EBUS-TBNA provides vital diagnostic information for appropriate patient management in our country where the prevalence of Lung cancer and Tuberculosis is high. 

Materials and Methods: A cross-sectional study was conducted and involved all the patients undergoing diagnostic EBUS-TBNA as a part of clinical care. The procedure was performed on an outpatient/inpatient basis in the pulmonary interventional room under conscious sedation. Aspirated materials were collected on glass slides and prepared by the pulmonologist. Cytological smears were processed in the cytopathology lab and diagnosis was categorized as neoplastic, non-neoplastic, or non-diagnostic.

Results: A total of 53 consecutive cases were enrolled in the study of which 38 cases had hilar lymph node sampling, 5 had lung sampling, 9 cases had both lymph node and lung sampling, and 1 had a mediastinal mass sampling. The highest number of cases were in the neoplastic diagnostic category amounting to 62.3% followed by non-neoplastic 26.4%. The overall non-diagnostic rate was 11.32 %. Non-Small Cell Carcinoma 22.64% (n=12) was the most common cytological diagnosis. A total of 5 cases had corresponding lung biopsies, 4 cases had the same cytological and histological diagnoses, and 1 case had cytological diagnoses with discordant histological diagnoses.

Conclusion: The present study shows that cytological material obtained from patients undergoing diagnostic EBUS-TBNA provides excellent diagnostic information and high diagnostic yield. Certainly, this helps in appropriate patient management.

Keywords: EBUS-TBNA, Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration, Lymph node cytology, mediastinal lymph nodes, pulmonary lesion.


Cytomorphologic and Cytodiagnostic Study of Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration specimens obtained from patients undergoing diagnostic Endobronchial Ultrasound for Mediastinal and Pulmonary Lesion

Introduction

Nepal is a country with a high prevalence of lung malignancy as well as tuberculosis.1,2 Enlargement of intrathoracic lymph nodes can be due to a variety of causes including infection, inflammation, neoplastic etiology, or just nonspecific reactive hyperplasia. Until recently, tissue diagnosis of intrathoracic lymph nodes was being done by computed tomography (CT)?guided fine needle aspiration/biopsy, mediastinoscopy, or thoracoscopy.3 These investigations had limitations in terms of tissue yield, safety profile, and cost.4,5 Recently, Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a relatively new and minimally invasive procedure for sampling mediastinal and hilar lymph nodes as well as lung mass.6 Although mediastinoscopy is still considered the gold standard for staging mediastinal lymph nodes in lung cancer, it requires general anesthesia and is more invasive than EBUS-TBNA.7 However, EBUS-TBNA can be performed as an outpatient procedure under local anesthesia and conscious sedation. The cytological material obtained from these sites provides vital diagnostic information for appropriate patient management. EBUS-TBNA is, therefore, a promising tool for the diagnosis of mediastinal adenopathy in a developing country like Nepal.8 This procedure has been recently introduced in our institute and the study regarding the cytological profile of EBUS-TBNA specimens has not been done in our country to our knowledge.

So we aimed to study cytomorphologic and cytodiagnostic studies of EBUS-TBNA specimens obtained from patients undergoing diagnostic EBUS-TBNA.

 

Materials and Methods

An observational, cross-sectional study was conducted in the cytopathology and histopathology laboratory of the Department of Pathology, Department of Pulmonology, Critical Care and Sleep Medicine, and Interventional Pulmonology Room for the period of 1 year from June 2019 to June 2020. Ethical clearance was ensured by the institutional review board of BP Koirala Institute of Health Sciences at the start of the study (Reference no: IRC/1677/019). The study included all the patients undergoing diagnostic EBUS-TBNA as a part of clinical care. However, patients refusing to give consent were not included in the study. A convenience sampling method was used. Based on the study done by Gahlot et al, the proportion of non-neoplastic diagnoses was 83%. To calculate the sample size the following formula was employed, sample size (n) = Z² x p x q/ e2, where z represents 1.96 at a 95% confidence interval, proportion (p) =83%, the complement of p (q) = 17% and the permissible error (e) which is 15% of p. After performing the calculations, the sample size was 35. However, to account for non-respondents, an additional 20% is added to the expected sample size. Consequently, the final sample size for the study was 42, including any samples exceeding the anticipated sample size.

The collected data were entered into Microsoft Office Excel 2013 software. Data analysis was done by using SPSS 23 (Statistical Package for Social Sciences).

EBUS-guided transbronchial needle aspiration was performed with a 22-gauge needle under ultrasound guidance using an Eboscope (EB 1970, Pentax). The procedure was performed on an outpatient/inpatient basis in the pulmonary interventional room under conscious sedation. The aspirated materials from the needle were expelled onto glass slides and slides were prepared according to each pass by the pulmonologist. All the cytological smears prepared were both air dried (for May-Grunwald-Giemsa staining) and wet fixed (95% alcohol) (for Papanicolaou staining). Specimens were processed to the cytopathology lab for routine Papanicolaou and May-Grunwald-Giemsa staining.

The non-diagnostic sample was categorized if there were no lymphocytes found in the lymph node, no bronchial epithelium or pigmented macrophages in lung sampling and the absence of atypical cells. The Non-Neoplastic sample was categorized if there was the presence of lymphocytes in the lymph node, bronchial epithelium, or pigmented macrophages in lung sampling, inflammation, and the absence of atypical cells. And finally, Neoplastic was categorized if there was the presence of atypical cells.

 

Results

A total of 53 consecutive cases were enrolled in the study. In our study, patients' age ranged from 21 to 81 years old with a mean age of 60.07 years old. Most of the patients involved in the study were of older age group (above 65 years). In this study, 62% were male and 38% were female with male to female ratio 1:0.6. In this study, 45 of 53 (85%) cases were smokers of which 60% (n=27) were male smokers. Also, our studies, show that 100% (n=33) of patients involved in the study having neoplastic pathology were smokers. Of the 53 consecutive cases, 38 cases had hilar lymph node sampling, 5 had lung sampling, 9 had both lymph node and lung sampling and 1 had mediastinal mass sampling.

 

Cytopathological Category:

These 53 EBUS specimens were broadly categorized into three (3) categories. The highest number of cases were in the neoplastic diagnostic category amounting to 33 cases and 62.3%. However, in 11.32 % of the cases, a definite diagnosis could not be made due to various reasons which will be discussed in the discussion section. Therefore the overall non-diagnostic rate was 11.32 % (n=6)

 

 

Table 1: Spectrum of Cytopathological Diagnosis

 

Figure 1: A: Necrotising Granulomatous lymphadenitis showing the aggregate of epitheliod histiocytes in necrotic background. (PAP, 400x). B: Small cell carcinoma (lymph node) showing cellular smears having atypical cells dispersed singly. Cells are round to oval having finely granular chromatin with a scant amount of cytoplasm. Nuclear molding, apoptotic bodies, mitosis, and inflammatory cells are observed in the background. (PAP, 400x). C: Non-small cell carcinoma possibly Adenocarcinoma from lung mass showing atypical cells arranged in cohesive clusters and glands in hemorrhagic background. (PAP, 200x). D: Squamous cell carcinoma from lung mass showing atypical squamous cells, dyskeratotic cells, and abundant necrosis in the background. (PAP, 400x).

 

Histopathological Diagnosis

Out of the cases that were reported as neoplastic and non-neoplastic, we received a total of 5 Histopathological specimens as Transbronchial lung biopsies (TBLB). Though the cytological sample were both from lymph node(n=4) and lung mass(n=1), histopathology, for all of these corresponding transbronchial lung biopsy was received. While comparing cytopathological diagnosis with histopathological diagnosis, all cases were concordance except for one histopathological case in which a descriptive report was given which will be discussed in the discussion section.

 

Discussion

EBUS-TBNA is a less invasive bronchoscopic technique that is safe, reliable, and cost-effective and is widelyused in the evaluation of mediastinal, hilar, and lung parenchymal lesions.6,9 This procedure has recently started in our BPKIHS institute in the Department of Pulmonology, Critical Care, and Sleep Medicine. There are many causes of mediastinal and hilar lymphadenopathy, such as neoplasms, granulomatous diseases, infections, and reactive hyperplasia. Since the introduction of EBUS-TBNA, its use has rapidly increased in staging lung carcinoma and in establishing the mediastinal lymph node status in other malignancies.9 Studies have shown that EBUS can improve the diagnostic yield for sampling mediastinal and hilar lymph nodes as well as peripheral lung lesions when compared with other procedures, such as mediastinoscopy, conventional TBNA, and transesophageal endoscopic ultrasound-guided fine-needle aspiration, and has shown high sensitivity (85%) and specificity (100%).6,7,9–11 Hence our study adopted EBUS-TBNA to see the cytomorphologic and cytodiagnostic study of EBUS-TBNA of specimens obtained from diagnostic EBUS-TBNA.   

In our prospective cross-sectional study, we analyzed the data of 53 consecutive patients. In our study, there were 47 adequate samples with a diagnostic yield of 88.68% and the non-diagnostic rate was 11.32%. Other studies have reported diagnostic yields ranging from 55.26% to 96%.10,12–14. This study shows a similar result on diagnostic yield as compared to other studies which are summarised in Table 4 except studies done by Darjani et al show a low percentage in diagnostic yield. However, their study used only TBNA without the use of EBUS and studies have shown that TBNA performed under imaging guidance like EBUS has increased the diagnostic yield.14 Similarly the study done by Yasufuku et al shows a higher percentage of diagnostic yield when compared to the present study as well as with other literature (Table 8). The possible cause of this excellent yield could be that the authors have implemented rapid onsite evaluation (ROSE). However, our study as well as the rest of the literature that we have taken into account also shows a high and comparable diagnostic yield despite only EBUS-TBNA without ROSE. The presence of ROSE is advocated for the determination of material adequacy, reduction of non-diagnostic rate, and preliminary diagnosis.6,15 Several factors such as the skill of the endoscopist, the size and station of the lymph nodes, sampling error, and the experience of performing on-site evaluation may contribute to the diagnostic yield.

 

 

Adequacy Criteria

Some adequacy criteria have been outlined in the literature for EBUS-TBNA though they are yet to be well established. A study done by Alsharif et al shows that the presence of 40 lymphocytes per high-power field in cellular areas of the smear and/or the presence of clusters of pigmented macrophages are good predictors of adequate sampling.19 Feller-Kopman et al proposed that the presence of moderate to abundant numbers of lymphocytes and/or pigmented macrophages is a good indicator of adequate sampling of lymph node and lung parenchyma in most cases because the amount of lymphoid tissue is likely dependent on not only the operator’s skill but also the degree of nodal replacement by granulomata or metastatic lesions.6 Hence our study also followed these criteria. Since we also had a good number of granulomatous lymphadenitis and neoplastic lesions, this method was justified for our adoption.


The Spectrum of Cytopathological Diagnosis

Studies had shown that the etiology of mediastinal lymphadenopathy differs in different regions of the world. Lymphoma and metastatic cancer are the common causes in developed countries, infections such as tuberculosis (TB) are more likely causes in developing countries.12

In our study, out of 53 cases, the majority of cases were Neoplastic (62.26%) in which Non-small cell carcinoma was the most common diagnosis. Similarly, the next common pathology was Non-neoplastic (26.42%) in which granulomatous lesion was seen in 4 cases and reactive lymphadenitis in 4 cases. In all cases of granulomatous lesions special stain for AFB was applied but no microorganisms were identified. However, there is low sensitivity of the acid-fast stain for the detection of Mycobacterium tuberculosis.16

The study done by Indian researcher Gahlot et al shows that among 92 cases, there was 71 granulomatous lymphadenitis. Malignancy was reported in 16 (17.3%) patients, and 5 (5.43%) were reported to have reactive lymphadenopathy.12 Another Indian study done by Srinivasan et al. reported 37 cases, in which sarcoidosis was 53.8%, TB was 23.3%, and malignancy was 17.9%.20 However, western literature reported malignancy as the main etiology. Herth et al. reported malignancy in 82% and granulomatous in 12% (sarcoidosis 9% and TB 3%).10 A study done by Darjani et al reported, atypical and malignant lesions in 11 cases (50%) followed by sarcoidosis in 8 (36.36%), tuberculosis (TB) in 2 (9.09%), and other diagnoses in 1 (4.55%) case which shows the similar frequency of neoplastic lesion similar to our studies14. However, the present study shows a higher frequency of neoplastic pathology, and the possible reason could be that the EBUS-TBNA procedure done by pulmonologists was mostly done for suspected lung carcinoma.

Adenocarcinoma is now the most common incident lung carcinoma while incident rates for both squamous cell carcinoma and small cell carcinoma have declined.21 In our study, the most common cytological diagnosis under the neoplastic category was Non-small cell carcinoma in which 4 cases were possible for adenocarcinoma and 5 cases were possibility for squamous cell carcinoma. Similarly, the next common pathology was small cell carcinoma followed by metastatic carcinoma, squamous cell carcinoma, adenocarcinoma, poorly differentiated carcinoma, and high-grade neuroendocrine carcinoma which is summarised in Table 3. The findings were similar to the study done by Indian researcher Nair et al, which shows a higher frequency of non-small cell carcinoma (n=18) followed by small cell carcinoma (n=6) and poorly differentiated carcinoma (n=2) in the EBUS-TBNA specimen.8 Similarly the study done by S.Pradhan et al in Nepal shows a higher frequency of squamous cell carcinoma 63.64% of cases followed by adenocarcinoma (29.09% of cases) and small cell carcinoma (7.27% of cases) showing a higher frequency of squamous cell carcinoma similar to the present study.22

 

Comparison between cytopathological diagnosis and histopathological diagnosis

In our study, out of 53, a total of 5 cases had a corresponding transbronchial lung biopsy. Among them, 4 cases had the same cytological and histopathological diagnosis except for 1 case in histopathological diagnosis in which a descriptive report was given. In this case, the reason for discordant histopathological diagnosis may be due to limiting factors involved in the yield of transbronchial lung biopsy procedure, including the distribution of lesion, the small size of the lesion, and failure to obtain a representative sample.23

 

Conclusions

The present study shows that cytological material obtained from patients undergoing diagnostic EBUS-TBNA provides excellent diagnostic information and high diagnostic yield. Certainly, this helps in appropriate patient management. EBUS-TBNA is a less invasive bronchoscopic technique that is safe, reliable, and cost-effective for the diagnosis of mediastinal lymphadenopathies as well as lung mass. EBUS-TBNA furthermore has proven more than adequate to obtain sufficient materials for further diagnostic workups like ancillary testing. And also it is a promising tool in a developing country like Nepal where there is a high prevalence of granulomatous disorders as well malignancy of the lung.

The main limitation of our study was that cytopathological diagnoses were not able to compare with histopathological diagnoses due to the unavailability of biopsy samples for all cases. Also, the ancillary test was not performed like immunohistochemistry due to unavailability in our center. Rapid on-site evaluation was not performed which would have increased diagnostic yield and diagnostic information.

To our knowledge, this type of study has not been investigated regarding cytological features of EBUS-TBNA before in our country. So, the multi- centered studies with larger sample sizes need to be conducted to determine the diagnostic utility of EBUS-TBNA. Histopathological examination is necessary for confirmatory diagnosis, hence it is recommended to take a Transbronchial lung biopsy and core biopsy of lymph nodes indicating the importance of histological diagnosis in planning proper and timely treatment.

 

Conflict of Interest: None.

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