Small-airway biopsy may help with diagnosing sarcoidosis: Study
More than a third of patients found to have abnormalities in bronchioles
More than one-third of sarcoidosis patients have abnormalities in the small airways, or bronchioles, according to a study in Italy that looked at small-airway inspection and biopsy using ultrathin tubes. The researchers said this procedure could aid in diagnosing sarcoidosis.
Small-airway biopsies yielded high rates of granuloma detection: 65.4% in patients with small airway abnormalities and 54.8% in those with lung abnormalities on CT scans. Granulomas are clumps of inflammatory cells that form in tissues and organs of people with sarcoidosis.
“We suggest that inspection and biopsy of the small airways using an ultrathin bronchoscope be considered as a possible diagnostic add-on to [standard methods] in patients who lack large airway abnormalities … known to frequently yield granulomas upon being sampled,” the researchers wrote.
The study, “Ultrathin bronchoscopy-guided small airway biopsy for diagnosing sarcoidosis: A prospective study,” was published in Pulmonology.
Sarcoidosis is characterized by the formation of granulomas, most often in the lungs and nearby lymph nodes (organs of the immune system), causing symptoms like shortness of breath and chronic cough. Diagnosis commonly includes imaging scans and biopsy, the collection of a small piece of the tissue to be examined.
Diagnosing sarcoidosis
Bronchoscopy is the usual procedure for lung biopsy. It involves passing a thin and flexible tube, called a bronchoscope, through the mouth or nose and down the airways, allowing the doctor to visualize the airways and collect tissue for analysis.
Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has become the first choice method of bronchoscopy sampling. It allows not only the collection of samples from the bronchi (the large tubes that carry air to the lungs) but also from the alveoli, the tiny air sacs where the smallest bronchioles end and gas exchange takes place.
EBUS-TBNA may fail to detect granulomas in up to 40% of sarcoidosis patients, and additional bronchoscopy biopsy techniques, such as transbronchial lung biopsy (TBLB), are used to improve diagnosis.
But TBLB carries a higher risk of complications, including pneumothorax, or air leakage into the space between the lungs and the chest wall, making lungs to partially or fully collapse.
The development of new, ultrathin bronchoscopes (UTBs) capable of inspecting bronchioles, the smaller branches of the bronchi, could enhance the ability to identify small airway abnormalities, while minimizing TBLB-associated risk of pneumothorax.
The researchers assessed the use of UTB for visualization of small airways and granuloma detection in 77 patients at their center with suspected sarcoidosis from October 2022 to December 2023. Sixty-five were diagnosed with sarcoidosis based on tissue analysis or clinical and imaging findings. These patients had a mean age of 57.9, and 55.4% were men.
Chest CT findings showed that 52.3% of the sarcoidosis patients had lymph node involvement alone, while 43.1% had both lymph node and lung involvement.
Large airway abnormalities, inspected with video bronchoscopy, were present in 41.5% of the patients, while small airway lesions, observed through UTBs, were detected in 40%.
Both large and small airway abnormalities were more common in patients with lung involvement than in those with lymph node involvement alone. Multiple, simultaneous patterns of airway abnormality were more frequent in patients with small airway abnormalities than in those with large airway abnormalities (34.6% vs. 3.7%).
The ability of UTB-based small airway biopsy to detect granulomas was significantly higher in patients with small airway lesions than those without (65.4% vs. 23.1%), and in those with lung involvement detected in CT scans relative to those without (54.8% vs. 26.5%).
Random small-airway biopsies taken from 39 patients without visible lesions on bronchoscopy identified granulomas in 23.1% of them.
Among the bronchoscopic sampling procedures, EBUS-TBNA “demonstrated the highest diagnostic yield for detecting granulomas,” the researchers wrote. This method detected granulomas in 89% of the patients, and was the only successful diagnostic method for 56.9% of the patients.
UTB-based small airway biopsy was the only successful diagnostic method in 6.2% of the patients. Analyzing both EBUS-TBNA- and UTB-based small airway biopsies was able to detect granuloma in 32.3% of the patients.
“No complications were observed following both small and large airway biopsy,” the team wrote.
The findings “underscore the diagnostic value of small airway biopsy in identifying … granulomas, particularly in patients with [small airway abnormalities] and [lung tissue] involvement on CT, where the diagnostic yield was notably higher,” the researchers wrote. “A study comparing UTB-directed [small airway biopsy] with conventional transbronchial lung biopsy, especially in terms of diagnostic yield and safety, would be critical in assessing the role of each technique in this setting,” they concluded.
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