Endoscopic ultrasound features of pancreatic solid lesions: Descriptive and predictive analysis on a multicenter sample

Abstract

Background: Endoscopic ultrasound (EUS) is crucial for diagnosing solid pancreatic lesions, especially pancreatic ductal adenocarcinoma (PDAC), a highly aggressive cancer which represents the majority with a prevalence of approximately 85%.

Aim: To identify EUS features that differentiate PDAC from other lesions such as neuroendocrine tumors (NETs) and helping in the differential diagnosis, by analyzing a large sample of solid pancreatic lesions.

Methods: This observational, retrospective, multicenter study analyzed the endosonographic characteristics of 761 patients with a radiological diagnosis of solid pancreatic lesion, who underwent pancreatic EUS for typing and staging with needle biopsies between 2015 and 2023. General patient characteristics (age and sex) and solid lesion features were collected and described, such lesion size (B-mode), vessel involvement (compression or invasion), ductal dilation, lymphadenopathy, echogenicity, echopattern, margin regularity, multifocality, internal vascularization and elastography. Subsequently, a predictive analysis was performed through univariate and multivariate logistic regression to identify predictive features for PDAC or NET diagnoses.

Results: Our study enrolled 761 patients, predominantly male with a mean age of 68.6. PDACs were generally larger (mean 33 mm × 27 mm), often had irregular margins, and displayed significant upstream ductal dilation. Hypoechogenicity was common across malignant lesions. In contrast, NETs were smaller (mean 20 mm × 17 mm) and typically had regular margins with multiple lesions. Vascular involvement, although predominant in PDAC, is a common feature of all malignant neoplasms. Multifocality, however, although a rare finding, is more typical of NETs and metastases, and practically absent in the remaining lesions. Predictive analyses showed that ductal dilation and irregular margins were the most significant predictors for PDAC [odds ratio (OR) = 5.75 and 3.83], with hypoechogenicity, heterogeneous echopattern and lymphadenopathies also highly significant (OR = 3.51, 2.56 and 1.99). These features were inversely associated with NETs, with regular margins and absence of ductal involvement or lymphadenopathies (OR = 0.24, 0.86 and 0.45 respectively), as already shown by the descriptive analysis. Finally, age, despite achieving statistical significance, lacks clinical value given an OR trending towards 1.

Conclusion: This study provides a comprehensive overview of EUS features for solid pancreatic lesions, identifying distinct features like upstream ductal dilation and irregular margins for PDAC vs regular margins for NETs as strong diagnostic predictors. These findings enhance the understanding of pancreatic pathologies, offering valuable insights for improved differential diagnosis and clinical management, especially in complex cases. Further prospective studies could build on these results.

Keywords: Endoscopic ultrasound; Endoscopic ultrasound features of pancreatic solid lesions; Endoscopic ultrasound-fine needle aspiration/fine needle biopsy; Focal pancreatitis; Pancreatic ductal adenocarcinoma; Pancreatic metastasis; Pancreatic neuroendocrine tumors; Pancreatic solid lesions.

Figure 1

Endoscopic ultrasound features of the total study sample and the subgroups.

Figure 2

In the first row, there is a hypoechoic neoplasm with irregular margins, a common bile duct invasion, and the measurement of the lesion in B-mode. In the second row, you can see an arterial invasion, a portal vein invasion, and a homogeneous neuroendocrine tumor with regular margins.