P4461 - Grading of Pancreatic Neuroendocrine Tumors by EUS FNA/FNB: A Tertiary Care Center Experience

Nitish Mittal, MD¹, Malek Satila, MD², Faisal Ali, MD³, Ingrid Schwartz, MD², Iyad Al-bustami, MD, MPH(c)⁴, Jennifer Ma, MD¹, Kazi Haque, MD⁵, Stephen Glombicki, MD³, Brian Weston, MD², William Ross, MD², Emmanuel Coronel, MD², Phillip Ge, MD², Jeffrey H.. Lee, MD, MPH, FACG^2
1University of Texas Health, McGovern Medical School, Houston, TX; ²MD Anderson Cancer Center, Houston, TX; ³University of Texas, Houston, TX; ⁴Brooklyn Hospital Center, Houston, TX; ⁵McGovern Medical School at UTHealth, Pearland, TX

Introduction: Grading of pancreatic neuroendocrine tumors (pNETs) plays an important role in the management of this condition. Discordance in tumor grading by endoscopic ultrasound (EUS) with fine needle aspiration/biopsy (FNA/FNB) when compared to surgical grading has been previously reported. We aim to explore factors associated with the diagnostic accuracy for tumor grading of pNETs using EUS FNA/FNB.

Methods: We performed a retrospective chart review of all adult patients with pNETs who underwent both EUS with FNA/FNB and surgery at our tertiary care institution from 2007 to 2022. For statistical analysis, Chi-square with Fisher’s exact test and Mann-Whitney U tests were performed.

Results: A total of 93 patients were included in this study. The majority of patient were white (82.6%) and female (51.1%), median age of 57 (44-65). Multiple endocrine neoplasia type 1 was present in 15 (16.3%), and 11 (12.0%) PNETs were functioning. Concurrent cancer was present in 37 (40.2%). The mean lesion size was 22.2 ± 1.2mm. Lesions were most commonly hypoechoic (66, 71.7%) and had well-defined walls (68, 73.9%). The remaining lesions were either heterogenous (14, 15.2%) or hyperechoic (2, 2.2%), and 15 (16.3%) had a cystic component. Metastatic pNET at diagnosis was present in 16 (17.4%). Most patients had a tumor grade of 1 (79; 85.9%) on EUS/FNA, followed by 11 (12.0%) with grade 2, and 1 (1.1%) with a well-differentiated grade 3 tumor. Sixty-two patients (67.4%) had concordant pathology between EUS FNA and surgical specimens, and 30 had EUS FNA (22.6%) underestimating tumor grading compared to surgical pathology. We found that cases that needed more than three passes on EUS more frequently led to underestimation of tumor grade on FNA (31% of patients with underestimation had more than three passes compared to 9.8% of those with concordant grade, p = 0.01). Aside from this, tumor size, location, needle type, type of surgery received, and trainee involvement did not significantly impact concordance.

Discussion: Our study is one of a few to explore factors associated with concordance between EUS FNA and surgical pathology tumor grading of pNETs. We found that around a third of FNAs may underestimate tumor grade. Future studies are needed to identify factors that can help predict EUS FNA/FNB and surgical pathology discordance.


Disclosures:


Nitish Mittal, MD¹, Malek Satila, MD², Faisal Ali, MD³, Ingrid Schwartz, MD², Iyad Al-bustami, MD, MPH(c)⁴, Jennifer Ma, MD¹, Kazi Haque, MD⁵, Stephen Glombicki, MD³, Brian Weston, MD², William Ross, MD², Emmanuel Coronel, MD², Phillip Ge, MD², Jeffrey H.. Lee, MD, MPH, FACG². P4461 - Grading of Pancreatic Neuroendocrine Tumors by EUS FNA/FNB: A Tertiary Care Center Experience, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.