Ultrathin bronchoscopy boosts small airway biopsy potential for diagnosing sarcoidosis

In patients with suspected sarcoidosis, small airway biopsy (SAB) guided by ultrathin bronchoscopy (UTB) shows promise for increasing the detection rate of granulomatous inflammation while minimizing the risk of pneumothorax associated with transbronchial lung biopsy (TBLB).

“In patients who lack easily accessible biopsy targets (eg, skin, peripheral lymph nodes, or conjunctiva), endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has become the first-choice biopsy method, due to its effectiveness, safety, and high prevalence of intrathoracic lymph node involvement in sarcoidosis,” said the researchers.

However, EBUS-TBNA falls short in detecting granulomas in up to 40 percent of patients with a final diagnosis of sarcoidosis, specifically in Scadding radiographic stages II and III of the disease. [Respirology 2022;27:152-160; Chest 2014;146:547-556; J Bronchology Interv Pulmonol 2014;21:220-226]

Clinicians thus supplement EBUS-TBNA with other techniques such as endobronchial biopsy or TBLB to improve the diagnostic yield and lessen inconclusive bronchoscopies. However, TBLB also falls short as a diagnostic add-on, especially for stage I disease, and it is associated with a higher risk of complications such as pneumothorax. [J Bronchology Interv Pulmonol 2018;25:31-36; J Thorac Cardiovasc Surg 2012;143:1324-1329]

“Ultrathin bronchoscopes [are] capable of inspecting airways beyond the fifth branching generation. [This] could enhance the ability to identify and biopsy small airway abnormalities (SAAs) under direct visualization,” said the researchers.

The investigators sought to evaluate SAA prevalence and patterns, and the diagnostic yield of UTB-directed SAB in 79 participants. The final analysis included data from the 77 patients who completed the study. [Pulmonology 2025;doi:10.1080/25310429.2024.2411806]

Sixty-five participants (mean age 57.9 years, 44.6 percent women) were diagnosed with sarcoidosis. All but two cases were histologically confirmed; the two cases were confirmed based on clinical and radiological findings.

Forty percent (n=26) of the patients diagnosed with sarcoidosis had SAAs. These were more prevalent among those who had parenchymal involvement on CT than those who only had lymphadenopathy (58.1 percent vs 23.5 percent; p=0.005).

Of the 12 patients who had a final diagnosis other than sarcoidosis, one had SAAs.

The diagnostic yield for granuloma detection was significantly higher among participants with vs without SAAs (65.4 percent vs 23.1 percent; p=0.001) and those with vs without parenchymal disease on CT (54.8 percent vs 26.5 percent; p=0.02).

“These findings support the hypothesis that granuloma burden in the airways is significantly higher in sarcoidosis patients with lung involvement, potentially influencing diagnostic strategies,” the researchers said.

Of note, random biopsies that were taken under direct visualization from small airway carinas demonstrated peribronchiolar parenchyma in 23 percent of participants.

Apart from a case of mediastinitis following EBUS-TBNA, there were no other clinically relevant complications observed, nor were there any complications following small and large airway biopsies.

Takeaways

“[O]ur results underscore the diagnostic value of SAB in identifying non-necrotizing granulomas, particularly in patients with SAAs and parenchymal involvement on CT, where the diagnostic yield was notably higher,” the researchers noted.

The findings suggest that inspection and biopsy of small airways guided by UTB should be considered as a potential diagnostic adjunct to EBUS-TBNA in patients who do not have large airway abnormalities (eg, nodularity, cobblestoning) that are usually known to yield granulomas upon sampling.

“In centres where rapid onsite evaluation is available, UTB could be considered in patients with inconclusive EBUS-TBNA cytology findings,” they added.