Primary Mediastinal Large B-Cell Lymphoma Achieved by Non-Cautery Assisted Transbronchial Mediastinal Cryobiopsy

Utility and safety of endobronchial ultrasound-guided transbronchial mediastinal cryobiopsy (EBUS-TMC): A systematic review and meta-analysis

BACKGROUND

Modalities to improve tissue acquisition during endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) have been investigated. Endobronchial ultrasound-guided transbronchial mediastinal cryobiopsy (EBUS-TMC) is a modality to obtain larger histological samples by inserting a cryoprobe into the mediastinal lesion. We aimed to study the diagnostic yield and safety of EBUS-TMC.

METHODS

We performed a systematic search of the PubMed and Embase databases to extract the relevant studies. We then performed a meta-analysis to calculate the diagnostic yield of EBUS-TMC and compare it with EBUS-TBNA.

RESULTS

Following a systematic search, we identified 14 relevant studies (869 patients undergoing EBUS-TMC and EBUS-TBNA). We then performed a meta-analysis of the diagnostic yield of EBUS-TMC and EBUS-TBNA from studies wherein both procedures were performed. The pooled diagnostic yield of EBUS-TMC was 92% (95% confidence interval [CI], 89%-95%). The pooled diagnostic yield of EBUS-TBNA was 81% (95% CI, 77%-85%). The risk difference in yield was 11% (95% CI, 6%-15%, I2 = 0%) when EBUS-TMC and EBUS-TBNA were compared. The only complication reported commonly with EBUS-TMC was minor bleeding. The complication rate was comparable with EBUS-TBNA.

CONCLUSION

EBUS-TMC provides a greater diagnostic yield with a similar risk of adverse events compared to EBUS-TBNA. Future studies are required to clearly establish which patients are most likely to benefit from this modality.

A Review of Endobronchial-Ultrasound-Guided Transbronchial Intranodal Forceps Biopsy and Cryobiopsy

Benign and malignant mediastinal lesions are not infrequently encountered in clinical practice. Mediastinoscopy has long been considered the gold standard in evaluating mediastinal pathology. Since its introduction into clinical practice, endobronchial-ultrasonography-guided transbronchial fine needle aspiration (EBUS-TBNA) has replaced mediastinoscopy as the initial procedure of choice to evaluate mediastinal lesions and to stage lung cancer. Its diagnostic yield in benign mediastinal lesions and less common malignancies, however, has remained limited. This has led different proceduralists to investigate additional procedures to improve the diagnostic yield of EBUS-TBNA. In recent years, different published reports concluded that the addition of EBUS-guided intranodal forceps biopsy (IFB) and transbronchial cryobiopsy (TBCB) to EBUS-TBNA increases the diagnostic yield especially in benign mediastinal lesions and uncommon mediastinal malignancies. The purpose of this review is to describe how EBUS-IFB and EBUS-TBCB are performed, to compare their diagnostic yields, and to discuss their limitations and their potential complications. In addition, the review will conclude with a proposed algorithm on how to incorporate EBUS-IFB and EBUS-TBCB into clinical practice.

Transbronchial needle aspiration combined with cryobiopsy in the diagnosis of mediastinal diseases: a multicentre, open-label, randomised trial

BACKGROUND

Transbronchial mediastinal cryobiopsy is a novel sampling technique for mediastinal disease. Despite the possibility of lung cancer misdiagnosis, the improved diagnostic yield of this approach for non-lung-cancer lesions compared with standard endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) highlights its diagnostic potential as a complementary technique to conventional biopsy. We aimed to evaluate the safety profile and added value of the combined use of transbronchial mediastinal cryobiopsy and standard EBUS-TBNA for the diagnosis of mediastinal diseases.

METHODS

We conducted an open-label, randomised trial at three hospital sites in Europe and Asia. Eligible patients were aged 15 years or older, with at least one mediastinal lesion of 1 cm or longer in the short axis that required diagnostic bronchoscopy. Participants were randomly assigned (1:1) using a block randomisation scheme generated by a computer (block size of four participants based on a random table from an independent statistician) to the combined use of EBUS-TBNA and transbronchial mediastinal cryobiopsy (combined group) or EBUS-TBNA alone (control group). Because of the nature of the intervention, neither participants nor investigators were masked to group assignment. The coprimary outcomes were differences in procedure-related complications and diagnostic yield (defined as the proportion of participants for whom mediastinal biopsy led to a definitive diagnosis), assessed in the full analysis set, including all the patients who met the eligibility criteria and had a biopsy. A fully paired, intraindividual diagnostic analysis in participants who had both needle aspiration and mediastinal cryobiopsy was conducted, in addition to interindividual comparisons. This trial is now complete and is registered with ClinicalTrials.gov, NCT04572984.

FINDINGS

Between Oct 12, 2020, and Sept 9, 2021, 297 consecutive patients were assessed for eligibility and 271 were enrolled and randomly assigned to the combined group (n=136) or the control group (n=135). The addition of cryobiopsy to standard sampling significantly increased the overall diagnostic yield for mediastinal lesions, as shown by both interindividual (126 [93%] of 136 participants in the combined group vs 109 [81%] of 135 in the control group; risk ratio [RR] 1·15 [95% CI 1·04-1·26]; p=0·0039) and intraindividual (126 [94%] of 134 vs 110 [82%] of 134; RR 1·15 [95% CI 1·05-1·25]; p=0·0026) analyses. In subgroup analyses in the intraindividual population, diagnostic yields were similar for mediastinal metastasis (68 [99%] of 69 participants in the combined group vs 68 [99%] of 69 in the control group; RR 1·00 [95% CI 0·96-1·04]; p=1·00), whereas the combined approach was more sensitive than standard needle aspiration in benign disorders (45 [94%] of 48 vs 32 [67%] of 48; RR 1·41 [95% CI 1·14-1·74]; p=0·0009). The combined approach also resulted in an improved suitability of tissue samples for molecular and immunological analyses of non-small-cell lung cancer. The incidence of adverse events related to the biopsy procedure did not differ between trial groups, as grade 3-4 airway bleeding occurred in three (2%) patients in the combined group and two (1%) in the control group (RR 0·67 [95% CI 0·11-3·96]; p=1·00). There were no severe complications causing death or disability.

INTERPRETATION

The addition of mediastinal cryobiopsy to standard EBUS-TBNA resulted in a significant improvement in diagnostic yield for mediastinal lesions, with a good safety profile. These data suggest that this combined approach is a valid first-line diagnostic tool for mediastinal diseases.

FUNDING

National Natural Science Foundation of China.

Thoracic SMARCA4-deficient undifferentiated tumor diagnosed by transbronchial mediastinal cryobiopsy: A case report

Thoracic SMARCA4-deficient undifferentiated tumors (SMARCA4-UT) have a poor prognosis and are often diagnosed at an inoperable advanced stage. Herein, we report a case of SMARCA4-UT diagnosed by endobronchial ultrasound-guided transbronchial cryobiopsy (EBUS-cryo). The patient was a 42-year-old man with a history of smoking. Chest computed tomography revealed a right upper lobe nodule and an enlarged #11s lymph node. Core tissues could not be obtained by EBUS-guided transbronchial needle aspiration (EBUS-TBNA) for diagnosis and mediastinal staging; hence, EBUS-guided intranodal forceps biopsy (EBUS-IFB) was performed. However, a detailed diagnosis beyond poorly differentiated carcinoma could not be obtained. Subsequent EBUS-cryo provided sufficient specimens for immunohistochemical and molecular evaluation and SMARCA4-UT was definitively diagnosed. Thus, EBUS-cryo could be of additional diagnostic value for uncommon tumors, such as SMARCA4-UT, conjointly with EBUS-IFB as well as EBUS-TBNA.