Evaluating endoscopic ultrasound-guided tissue acquisition for diagnosis of small pancreatic neuroendocrine neoplasms

Abstract

Background and study aims Although small hypervascular tumors are suspected to be pancreatic neuroendocrine tumors (p-NENs), their diagnosis and treatment are challenging. This study evaluated the usefulness of endoscopic ultrasound-guided tissue acquisition (EUS-TA) for diagnosis of small p-NENs. Methods All p-NEN lesions that underwent EUS-TA at our hospital between April 2018 and December 2023 were retrospectively analyzed. The diagnostic sensitivity of EUS-TA and the concordance rate of grading with EUS-TA and surgical specimens were examined. The lesions were grouped by size. Results The diagnostic sensitivity of EUS-TA was analyzed for 82 lesions, of which 44 were compared with postoperative specimens for grading. The definitive diagnosis was neuroendocrine tumor (NET) in 75 lesions, neuroendocrine carcinoma in five lesions, and mixed neuroendocrine non-neuroendocrine neoplasm in two lesions. Thirty tumors were ≤10 mm, 30 were 10 to 20 mm, and 22 were >20 mm, and the diagnostic sensitivities were 96.7%, 96.7%, and 90.9%, respectively. Concordance rates for grading were 94.4%, 82.4%, and 77.8% for tumors ≤10 mm, 10 to 20 mm, and ≥20 mm, respectively, with Cohen's kappa coefficients of 0.64, 0.48, and 0.40, respectively. Conclusions EUS-TA showed adequate diagnostic sensitivity and grading agreement for p-NENs of all sizes, allowing for determination of appropriate treatment.

Keywords: Endoscopic ultrasonography; Fine-needle aspiration/biopsy; Pancreas; Tissue diagnosis.

Fig. 1

Study flow chart. p-NEN, pancreatic neuroendocrine neoplasm; EUS-TA, endoscopic ultrasound-guided tissue acquisition; NET, neuroendocrine tumor; NEC, neuroendocrine carcinoma; MiNEN, mixed neuroendocrine non-neuroendocrine neoplasm; p-NET, pancreatic neuroendocrine tumor.

Fig. 2

Representative images of diagnosis of small pancreatic neuroendocrine neoplasm using endoscopic ultrasound-guided tissue acquisition (EUS-TA). The smallest tumor diameter for which grading in this study could be assessed was 5 mm. The left row shows the EUS-TA specimen and the right row shows the surgical specimens (green arrowheads indicate the tumor site). The uppermost left row shows the EUS image and the uppermost right row shows the surgical specimen. The middle two rows are hematoxylin and eosin-stained sections and the bottom row is a section stained for Ki-67.