IP Journal Club | Interventional Pulmonology & Critical Care

🩺 Clinical Context

Undiagnosed pleural effusions remain a diagnostic challenge in interventional pulmonology. While image-guided pleural biopsy is standard, diagnostic yield for malignant pleural disease can be limited by sampling error. Needle-based Confocal Laser Endomicroscopy (nCLE) offers real-time, in vivo microscopic imaging of the pleura, potentially increasing diagnostic accuracy by guiding biopsies toward high-yield areas, thereby reducing the need for repeat procedures or more invasive surgical interventions.

📊 Methodological Strengths & Weaknesses

Strengths:

Multicenter, randomized controlled trial (RCT) design provides high-level evidence compared to existing observational data.
Standardized protocol for nCLE application and biopsy technique minimizes operator variability.
Clear definition of primary and secondary endpoints, including diagnostic yield and safety profiles (e.g., pneumothorax, bleeding).

Weaknesses:

The study is a protocol paper; actual clinical outcomes are pending.
Potential for selection bias in patient enrollment, as patients with highly suspicious imaging may be prioritized.
The learning curve associated with nCLE interpretation may impact the generalizability of the results to centers with less experience.
The study design may not fully account for the heterogeneity of pleural pathologies (e.g., benign vs. malignant, inflammatory vs. neoplastic).

💡 Takeaway for Fellows

Keep a close eye on the final results of COLLABORATION-II. If nCLE proves to significantly increase diagnostic yield, it could become a standard adjunct in the diagnostic workup of undiagnosed exudative effusions. For now, continue to rely on established ultrasound-guided biopsy techniques, but be aware that real-time microscopic guidance may soon shift the paradigm in how we approach pleural sampling.

Original Abstract

Background: The diagnosis of exudative pleural effusion is challenging. Although ultrasound-guided pleural biopsy (UGBx) is common, its effectiveness varies, especially in the absence of pleural abnormalities. New imaging techniques have been explored to improve UGBx outcomes, but the results remain inadequate. Recently, needle-based confocal laser endomicroscopy (nCLE) has been used to improve biopsy targeting and diagnostic yield through real-time cellular-level imaging; however, robust evidence is lacking. This trial aims to assess the diagnostic yield and safety of nCLE-assisted UGBx for unknown exudative pleural effusions. Methods: COLLABORATION-II is a multicenter randomized controlled study in China involving 324 participants across ten centers. Participants will be divided into two groups based on the ultrasound findings: Group 1 with pleural thickening (>5 mm) and/or pleural nodularity, and Group 2 with thickness ≤ 5 mm and no nodularity. Each group will be randomly assigned to either the nCLE-assisted UGBx or UGBx arm at a 1:1 ratio, with a 12-month follow-up. The primary outcome is the overall diagnostic yield, while secondary outcomes include the biopsy success rate, diagnostic sensitivity for specific diseases, complication in incidence, and specimen characteristics, such as size, quality, interpretability, and adequacy for achieving molecular diagnosis. Discussion: We hypothesize that the nCLE-assisted UGBx will achieve higher diagnostic yield than conventional UGBx by providing real-time, cellular-level visualization and targeted sampling of pathological areas. If this hypothesis is validated, nCLE-assisted UGBx could emerge as a novel and effective option for diagnosing patients with unknown exudative pleural effusion. Trial registration: This study has been registered at www.clinicaltrials.gov (Registration number: NCT07040241; Registration Date: 2025-06-26).