Endobronchial ultrasound diagnostic yield for sarcoidosis in hilar vs. mediastinal lymph nodes

Introduction

Sarcoidosis is a systemic disease of unclear etiology that is characterized by non-caseating granulomatous inflammation which can affect any organ (1). The estimated prevalence of sarcoidosis in the United States is about 60 per 100,000 people, with a higher prevalence in African Americans (2-4). Pulmonary involvement is seen in about 90% of sarcoidosis patients and often presents with hilar and mediastinal lymphadenopathy and a variety of pulmonary parenchymal findings on radiographic studies (5,6). Pulmonary sarcoidosis is diagnosed based on the clinical presentation and radiological findings, and a biopsy is often required to confirm the diagnosis (6,7). The standard targets of the biopsy are hilar and mediastinal lymph nodes in patients with lymphadenopathy seen in stage I and II pulmonary sarcoidosis (1,6). Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has become the procedure of choice, as the diagnostic yield is better than conventional TBNA and it is less invasive compared to mediastinoscopy (1,7-10). The current guidelines also endorse EBUS-TBNA for the evaluation of sarcoidosis (7,11,12). However, it remains unknown if the diagnostic yield of EBUS-TBNA for non-caseating granulomatous inflammation varies between hilar and mediastinal nodal stations. Compared to the hilar node, the mediastinal nodes are usually larger and easier to access, and if there is a difference in the diagnostic yield, it can inform the diagnostic approach. We conducted this retrospective study to compare the diagnostic yield of EBUS-TBNA for non-caseating granulomatous inflammation between the hilar and mediastinal nodes in all patients who underwent EBUS-TBNA for suspected sarcoidosis. We present this article in accordance with the STARD reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-598/rc).

Methods

We retrospectively reviewed the medical records and included all patients who underwent EBUS-TBNA at a single tertiary care hospital, Duke University Medical Center (Durham, NC, USA), to investigate hilar and mediastinal lymphadenopathy seen on the CT chest for suspected sarcoidosis between January 2015 and March 2021. The patients were excluded if the EBUS-TBNA was performed for evaluation of non-sarcoidosis diagnoses, like malignancy. The diagnostic yield of EBUS-TBNA for non-caseating granulomas was defined as the percentage of lymph nodes or patients with cytological confirmation of non-caseating granulomas over a total number of nodes or patients biopsied, respectively. This definition has been previously used in other studies (1,8). The non-caseating granulomas were identified when groups of closely aggregated epithelioid histiocytes with ovoid or elongated nuclei without necrosis were seen, often with multinucleated giant cells, and negative acid-fast bacilli and fungal stains or cultures on all specimens (13). The data collection included demographics and details of the procedure, including the lymph node stations biopsied, lymph node size, biopsy needle size, number of biopsy passes, and the lymph node biopsy results. The hilar and mediastinal nodal stations were identified using the International Association for the Study of Lung Cancer (IASLC) lymph node map and suggested landmarks (14). EBUS accessible mediastinal stations included stations 2, 3P, 4, and 7, and hilar stations included 10, 11, and 12. Sarcoidosis was diagnosed based on American Thoracic Society Guideline definition, which was used by other publications as well (7,8). Definitive sarcoidosis was defined based on typical clinical and radiographic features and the finding of non-caseating granulomas on EBUS-TBNA, transbronchial biopsy, endobronchial biopsy, mediastinoscopy, or other organ biopsies on a one-year follow-up (7,8). Probable sarcoidosis was defined as clinical and radiographic features of sarcoidosis and the absence of alternate diagnosis when the biopsies were negative, but the treating physicians diagnosed the patient with sarcoidosis on a one-year follow-up (7,8). The one-year follow up included clinic visits, further imaging, and as clinically indicated, additional biopsies if the EBUS-TBNA was negative. Conditions that can lead to granulomatous inflammation like infections, malignancy, vasculitis, and occupational exposures were excluded by appropriate work-up by the treating physicians when diagnosing sarcoidosis.

EBUS was performed under moderate sedation until February 2016 and with general anesthesia afterwards. The EBUS bronchoscope (Olympus, Center Valley, PA, USA) was introduced through the airway, and target nodes were identified. The EBUS needle (Olympus) was introduced into the target lesion under direct ultrasound visualization, the stylet was removed, and suction was applied. The needle was moved back and forth to collect the specimen, the suction was turned off, the needle was removed, and the aspirate was further processed. One to two aspirates were placed on slides and stained with Diff Quik for rapid on-site cytological evaluation (ROSE) to determine specimen adequacy (15). The rest of the passes were placed in 95% formalin or sterile saline for cytological examination or cultures, per the standard institutional work flow as previously described (16).

The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the institutional review board of Duke University Medical Center (IRB protocol Pro00107694) and individual consent for this retrospective analysis was waived.

Statistical analyses

Continuous variables were summarized as median and interquartile range (IQR) [first quartile (Q1), third quartile (Q3)] and categorical data as percentages. Continuous outcomes were compared with a Wilcoxon rank sum test, and categorical outcomes with a Chi-squared test. A generalized estimating equation (GEE) model for the binomial distribution with a logit link was fit to evaluate the relationship of the binary outcome diagnostic yield and baseline variables. This model also accounted for the repeated measures taken by the same patient. An exchangeable correlation structure was selected using the Quasilikelihood Under Independence Criterion (QIC) model selection method. We excluded certain variables from the adjusted model due to a lack of association with the outcome. However, we made an exception for the hilar vs. mediastinal lymph node and needle size due to their clinical relevance to the outcome. A two-sided P value of ≤0.05 was considered statistically significant.

Results

The study included 225 patients, who all underwent EBUS-TBNA for evaluation of sarcoidosis. In addition to EBUS-TBNA, some of the patients also had endobronchial or transbronchial biopsies (Table S1). The patient characteristics are shown in Table 1. The median age [IQR] was 54 [43–63] years. Females accounted for 61.3% of the cohort. There were 44.9% African Americans, 48.4% Caucasians, 1.8% Asians, and others. There were 4.9% smokers and 2.7% patients who used vaping devices.

The EBUS-TBNA was performed on 144 hilar and 255 mediastinal nodes (Table 2). The median lymph node size on EBUS for hilar and mediastinal nodes was 12 and 18 mm, respectively (P<0.001). The needle sizes included 19G, 21G, and 22G for biopsy of 63.2%, 4.2%, and 26.4% hilar and 62%, 3.5%, and 26.3% mediastinal nodes, respectively (P=0.90). Median [IQR] biopsy passes were 4 [3–5] for hilar and 4 [4–5] for mediastinal nodes, respectively (P=0.03). The final cytology results from EBUS-TBNA showed non-caseating granulomas, normal lymphocytes, cancer, and blood or bronchial epithelium in 61.8%, 24.3%, 0, and 3.9% hilar, and 65.5%, 23.5%, 0.8%, and 10.2% mediastinal nodes, respectively (P=0.49). No complications were reported from the procedures.

The overall diagnostic yield of EBUS-TBNA for detecting non-caseating granulomas in all thoracic lymph nodes biopsied was 78.2% (Table S2). As shown in Table 3, the diagnostic yield of EBUS-TBNA in detecting non-caseating granulomas was 61.8% for hilar nodes and 65.5% for mediastinal nodes (P=0.46). The diagnostic yield of EBUS-TBNA in detecting non-caseating granulomas in patients who underwent hilar nodes biopsy only, mediastinal nodes biopsy only, and both hilar and mediastinal nodes biopsy was 71.4%, 67%, and 73.1%, respectively (P=0.63), as shown in Table 4 and Figure 1. Non-caseating granulomas were seen with transbronchial biopsies in 13.8% of patients and endobronchial biopsies in 12.9% of patients, as shown in Table S1. The combined diagnostic yield of EBUS-TBNA, transbronchial and endobronchial biopsies for non-caseating granulomas was 82.7% (Table S2).

Figure 1 Diagnostic yield of EBUS-TBNA for non-caseating granulomas in patients with different lymph node station biopsies. EBUS-TBNA, endobronchial ultrasound-guided transbronchial needle aspirate.

Sarcoidosis was diagnosed in 206 (91.6%) out of 225 patients in the cohort on a one-year follow-up. Definitive sarcoidosis was seen in 192 (85.3%) and probable sarcoidosis in 14 (6.2%) patients. The sensitivity for sarcoidosis of EBUS-TBNA of hilar vs. mediastinal nodes was 66.9% [95% confidence interval (CI): 58.9–74.9%] vs. 71.1% (95% CI: 65.3–76.9%), as shown in Table 3 and Table S3. The specificity for sarcoidosis of EBUS-TBNA of both hilar and mediastinal nodes was 100% (Table 3 and Table S3).

To assess the association of different variables which are correlated with the diagnosis of sarcoidosis, we used lymph node location, lymph node size, needle size, needle passes, age, gender, body mass index (BMI), smoking status and race in univariate regression analysis. The variables of interest, like lymph node location, lymph node size, needle size, needle passes and significant variables from univariate regression like age and BMI were then used in multivariate regression analysis. Univariate regression analysis showed that diagnostic yield of EBUS-TBNA in detecting non-caseating granulomas was associated with number of needle passes [odds ratio (OR) 1.21; 95% CI: 1.02–1.44; P=0.03], age (OR 0.96; 95% CI: 0.94–0.97; P<0.01) and BMI (OR 1.05; 95% CI: 1.01–1.10; P <0.01), as shown in Table 5. In multivariable analysis, the diagnostic yield of EBUS-TBNA in detecting non-caseating granulomas was only associated with age (OR 0.96; 95% CI: 0.94–0.98; P<0.01).

Discussion

This is one of the first studies to systematically examine the diagnostic yield of EBUS-TBNA for non-caseating granulomatous inflammation between hilar and mediastinal lymph nodes in a multiracial cohort. Although the mediastinal nodes were larger than the hilar nodes, the EBUS-TBNA diagnostic yield for either hilar or mediastinal nodes was similar. In addition, the younger the age, the higher the diagnostic yield for non-caseating granulomatous inflammation while adjusting for nodal station, node size, needle size, biopsy passes, and BMI.

Different factors, like size of the lymph nodes, needle passes, etc., are associated with an increase in EBUS-TBNA diagnostic yield for non-caseating granulomas (17). However, the influence of lymph node location on EBUS-TBNA yield has not been studied systematically and this guidance may help prioritize biopsy approach, especially if ROSE is not available. In a retrospective registry, the diagnostic yield of EBUS-TBNA for non-caseating granulomas in suspected sarcoidosis patients in a propensity-matched cohort was 83.6% in the 19G group and 80.2% in the 21G/22G group (P=0.60) (18). The difference in yield between hilar and mediastinal nodes was not studied. The results are similar to those of our study, as we did not find evidence of a significant difference in the diagnostic yield between different needle sizes. In a multicenter, randomized controlled trial, 185 patients with suspected sarcoidosis were randomized to EBUS-TBNA and 173 patients to endoscopic ultrasound-fine needle aspiration (EUS-FNA) (10). Granuloma detection rate was 70% for EBUS-TBNA and 68% for EUS-FNA (P=0.67). There was no comparison of diagnostic yield between hilar and mediastinal nodes, however, the diagnostic yield of EBUS-TBNA is similar to ours. In a prospective study by Sun et al. from China, 111 patients with suspected sarcoidosis underwent EBUS-TBNA (17). The diagnostic yield of EBUS-TBNA for non-caseating granulomas increased with size, stage 1 sarcoidosis (compared to stage 2), and ≥2 needle passes (compared to one pass). EBUS-TBNA showed granulomas in 79 out of 103 (76.7%) hilar 148 out of 181 (81.8%) mediastinal lymph nodes, P=0.54. Our study extends the literature as the cohort is multiracial, and the details of nodal size, needle size, and number of needle passes are compared between hilar and mediastinal nodes. Although younger patients had a higher diagnostic yield of non-caseating granulomas, node size, and needle passes were not associated with a higher yield. We speculate that the needle passes were not associated with a higher diagnostic yield in our study as the median number of needle passes was 4 per node, which is already above the range of 3–4 needle passes where the diagnostic yield of EBUS-TBNA reached a plateau in Sun’s and others studies (17,19). In a meta-analysis, including 14 studies and 2,097 patients, the EBUS-TBNA yield varied from 33% to 100%, but the mean pooled diagnostic yield was 0.79 (standard deviation, 0.24) (20). In another meta-analysis, a similar pooled diagnostic yield of 79% (95% CI: 71–86%) was reported, and ROSE did not affect the diagnostic outcome (21). The diagnostic yield of EBUS-TBNA in our cohort is similar. The sensitivity and specificity of EBUS-TBNA for sarcoidosis in our cohort are similar to what is reported in other retrospective studies (20).

We found that odds of finding non-caseating granulomas increased with younger age in univariate and multivariate analyses. Sarcoidosis in the US is generally seen at younger age, though there has been a shift to older age in the recent studies (2,5,6). The median age [IQR] of our cohort was 54 [43–63] years, similar to the published literature (2,5,21). A study evaluated the association of age with cytological diagnosis of sarcoidosis in 89 patients who underwent EBUS-TBNA (22). Younger age was an independent predictor of cytological diagnosis of non-caseating granulomas in univariate and multivariable regression analysis, similar to the findings of our study. It has been suggested that older age is associated with a decline in immune response, which can lead to decreased T helper 1 (Th1) mediated granulomatous inflammation to environmental antigens (23). It has also been shown that there is an increase in regulatory T cells (Tregs) with decreased naïve and helper T cells in lymph nodes in elderly which can suppress the granulomatous immune response (24,25).

Other host factors are also associated with sarcoidosis. The prevalence of sarcoidosis is lower in smokers (26), but higher in African-Americans compared to other races (27), women (28), and obese (26). The adipose tissue in obesity has been associated with increased pro-inflammatory cytokines and shift in immunological phenotype to Th1, which may increase the predisposition towards sarcoidosis (29). Therefore, we used these variables to assess the association with EBUS-TBNA diagnostic yield of non-caseating granulomas. However, none of these variables were significant in multivariate regression analysis.

The strengths of this study include a detailed assessment of EBUS-TBNA yield of hilar and mediastinal nodes in a large, multiracial cohort of patients with sarcoidosis. The data included details of hilar vs. mediastinal biopsy location, lymph node size, different needle sizes, and number of needle passes. Our study is limited by its retrospective, single center design. Because of the utilization of ROSE, not all patients underwent both hilar and mediastinal node biopsies, and the procedure was stopped if a larger hilar or mediastinal node aspirate showed non-caseating granulomas. This might have introduced selection bias due to procedural sequencing and explain why the yield of smaller hilar nodes was lower but this difference was not statistically significant. However, 104 out of 225 patients (46.2%) underwent biopsies of both hilar and mediastinal stations. There was a slight but statistically non-significant increase in the diagnostic yield of EBUS-TBNA for non-caseating granulomas when both hilar and mediastinal stations were biopsied, which may suggest that multi-station sampling may improve the diagnostic yield, especially when ROSE is not available. Future prospective, multi-center studies are warranted to assess this further.

Conclusions

In conclusion, we did not find a statistically significant difference in the diagnostic yield of EBUS-TBNA between hilar and mediastinal lymph nodes. If clinically warranted, we recommend patients with suspected sarcoidosis should undergo biopsy of both hilar and mediastinal stations, especially if ROSE is not utilized.

Acknowledgments

We acknowledge the struggle and persistence of our patients with sarcoidosis, their families, and healthcare providers managing them.

Footnote

Reporting Checklist: The authors have completed the STARD reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-598/rc

Data Sharing Statement: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-598/dss

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-598/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-598/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the institutional review board of Duke University Medical Center (IRB protocol Pro00107694) and individual consent for this retrospective analysis was waived.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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