Background and objective: Accessory spleen (AS) may be encountered as an intrapancreatic lesion on EUS. This can look similar to other pancreatic pathologies and may lead to unnecessary interventions. The goal of this study was to evaluate the accuracy of EUS in distinguishing intrapancreatic AS (IPAS) from other pancreatic lesions.
Materials and methods: Twelve sets of endoscopic images of the spleen and various pancreatic lesions confirmed on histology or cytology were gathered. Ten endosonographers were asked to characterize and identify the lesions. The responses were analyzed via Excel and the interobserver agreement was analyzed using Gwet's agreement coefficient statistic via Stata I/C v15.
Results: In our sample, the interobserver agreement was 0.37 (-+1-1; 0-0.2 poor, 0.2-0.4 fair, 0.4-0.6 moderate, 0.6-0.8 substantial, and 0.8-1.0 almost perfect) for determining whether or not the pancreatic lesion is IPAS. The reviewers were able to correctly determine IPAS endosonographically with a sensitivity of 77%, specificity of 74%, and positive and negative predictive values of 50% and 92%, respectively.
Conclusion: There is a moderate-to-substantial interobserver agreement in describing the sonographic characteristics of the pancreatic lesions, such as the shape, echogenicity compared to spleen, echotexture, and border of the lesions. However, the interobserver agreement is only fair when deciding if the pancreatic lesion is an IPAS. The similar profile of IPAS and pancreatic neuroendocrine tumor could confound the diagnosis of IPAS, thus contributing to the decreased interobserver agreement. This study demonstrates that EUS criteria alone are not accurate for IPAS diagnosis. Fine-needle aspiration (FNA) may be required for a confirmatory diagnosis.
Keywords: Accessory spleen; EUS; interobserver variability.