Diagnostic role of endoscopic ultrasonography in defining the clinical features and histopathological spectrum of gastroenteropancreatic neuroendocrine tumors.

Background: Neuroendocrine tumors (NETs) are rare malignancies arising from the diffuse neuroendocrine system, often in the gastroenteropancreatic (GEP) tract. GEP-NETs, primarily involving the intestines (50%) and pancreas (30%), may occasionally secrete hormones, causing syndromes. Diagnosis relies on markers like chromogranin A, synaptophysin, and Ki-67, along with imaging modalities. Rising NETs incidence is attributed to advancements in diagnostic modalities, particularly endoscopic ultrasonography (EUS). EUS demonstrates high accuracy in detecting small lesions, assessing tumor depth, and identifying locoregional lymph nodes. Despite its proven diagnostic utility, there is limited data on EUS's role in evaluating GEP-NETs in resource-constrained settings like Pakistan.

Aim: To evaluate the diagnostic role of EUS in characterizing GEP-NETs based on clinical, histopathological, tumor grading, and site-specific differences.

Methods: This single-center retrospective descriptive study was conducted at Aga Khan University Hospital, Karachi, a tertiary care hospital, from January 2021 to December 2023. Fourteen adult patients (≥ 18 years) with suspected NETs who underwent EUS and were diagnosed via histopathology were included. Data on demographics, clinical features, radiological findings, and histopathological characteristics were collected. Descriptive analysis was performed using SPSS version 23, with descriptive statistics expressed as means ± SD for continuous variables and frequencies/percentages for categorical data.

Results: A total of 14 adult GEP-NETs patients who underwent EUS were included, with a mean age of 52 ± 14 years and the majority being male (71.4%). Common clinical presentations included weight loss (85.7%) and abdominal pain (78.6%). Computed tomography scans were performed in 92.9% of cases, with pancreatic masses detected in 42.9% of patients. EUS-guided fine needle biopsy (FNB) had a 100% diagnostic yield. The pancreas was the most common tumor site (57.1%). Histopathology revealed 78.6% of cases as well-differentiated NETs with 42.9% being grade II. Metastases were seen in 57.1% of patients, with the liver being the most common site. Surgical interventions were performed in 28.6% of patients, and all patients were alive at the time of study analysis.

Conclusion: EUS, with accurate imaging and effective EUS-FNB, is the gold standard for GEP-NET diagnosis, aiding tumor assessment and prognosis. Larger studies are needed to validate its impact on management outcomes.