Post written by Antonio Facciorusso, MD, from the Gastroenterology Unit, University of Foggia, Foggia, Italy.

The low sensitivity, reported to be as high as 54% in differentiating mucinous from non-mucinous pancreatic cystic lesions (PCLs), represents a major drawback of standard endoscopic ultrasound (EUS) fine-needle aspiration (FNA). Recently, a through-the-needle microforceps biopsy (TTNB) device that can be passed through a standard 19-gauge EUS-FNA needle was developed for histologic sampling of PCLs. There is currently limited evidence supporting the use of TTNB for sampling PCLs.

The aim of this meta-analysis was to provide a pooled estimate of the diagnostic performance and safety profile of through-the-needle microforceps biopsy for sampling of PCLs, thus attempting to determine its comparative efficacy with respect to standard FNA.

Through a meta-analysis of 11 studies, we made several key observations. First, overall sample adequacy rate with TTNB was 85.3%, with diagnostic accuracy and sensitivity  of 78.8% and 82.2%, respectively. These findings represent a striking result considering that current techniques (FNA with cystic fluid analysis) showed median diagnostic accuracy and sensitivity values of less than 50%. TTNB clearly outperformed standard FNA in comparative pairwise meta-analysis, showing a clear advantage in terms of sample adequacy (odds ratio 4.83, 1.63-14.31; P=0.004) and diagnostic accuracy (odds ratio 3.44, 1.32-8.96; P=0.01). Second, the diagnostic performance of TTNB was confirmed in sub-analysis performed according to cyst morphology (unilocular versus septated), size (<3 cm versus ≥3 cm), and location (head/uncinate versus body/tail). Finally, the TTNB technique was relatively safe, although 4% of enrolled patients experienced mild bleeding and 2% experienced pancreatitis; of note, these adverse events were mild and did not influence significantly the clinical course of the patients.

In spite of the undoubted advantages of TTNB in comparison to FNA, diagnostic accuracy and sensitivity are still considerably inferior to solid pancreatic masses. In fact, it is possible to sample only the opposite wall of the PCL with respect to the point of entrance of the needle and due to the uneven distribution of dysplasia inside the PCLs, there is a considerable risk of underestimating the real grade of dysplasia inside the cyst.

The lack of randomized trials represents a major limitation to the study. Therefore, there is a pressing need for large, multicenter, randomized-controlled trials in order to confirm these results.

Figure 3. Meta-analysis comparing rates of sample adequacy between microforceps biopsy and standard fine-needle aspiration (cytology/cyst fluid analysis). Microforceps biopsy (MFB) was significantly superior to FNA in targeting pancreatic cysts (odds ratio, 4.83; 95% confidence interval, 1.63-14.31; P =.004; I² = 36%). CI, Confidence interval; M-H, Mantel-Haenszel test; MFB, microforceps biopsy.

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