Endoscopic ultrasound is the reference modality for locoregional staging of ampullary cancer, but standard endoscopic forceps biopsies often inadequate diagnostic malignancy or underestimate histological grade. EUS-guided fine-needle biopsy (EUS-FNB) may overcome these limitations by providing core tissue; however, its performance for ampullary cancer has not been reported in Vietnam. We aimed to evaluate the diagnostic performance and safety of EUS-FNB for suspected ampullary cancer in a tertiary oncology hospital.

We conducted a single center prospective observational study at Viet Nam National Cancer Hospital including consecutive patients with suspected ampullary cancer who underwent  EUS-FNB between January 2022 and June 2025.  EUS-FNB was performed using dedicated biopsy needles with MOSE to assess core adequacy. Demographic data, clinical presentation, tumor markers, imaging findings, EUS characteristics, number of needle passes and post surgical results were recorded.  Final diagnosis was based on surgical histology or composite clinical follow-up. Diagnostic performance indices of EUS-FNB for ampullary cancer were calculated. Adverse events were prospectively documented.  

Among 54 evaluated patients, 46 met inclusion criteria and were analyzed. 43 (93.5%) had ampullary cancer, and 3 (6.5%) had non-malignant lesions.  Median age was 62.91+9.33 years, with most patients aged 40–70 years. Jaundice was the dominant symptom (90.7%).  A total of 60 EUS-FNB procedures were performed (mean 1.3 per patient) with a mean of 6.72 passes per lesion. MOSE positive core tissue was obtained in 35/46 cases (76.1%).  On histology of the EUS-FNB samples, definite ampullary carcinoma was reported in 25 patients (54.3%), high-grade dysplasia in 3 (6.5%), “suspicious / atypical cells” in 13 (28.3%) and low-grade dysplasia in 5 (10.8%).  Using final surgical histology or long-term follow-up as reference, EUS-FNB for ampullary cancer showed a Se of 93.0%, Sp 66.7%, PPV 97.6% and overall accuracy 91.3%.  No severe adverse events occurred; two patients (4.6%) developed transient abdominal pain and one (4.6%) experienced minor intra procedural bleeding. 

Table 1: The Value of EUS-FNB in Diagnostic Ampullary Cancer 

Table 2: The Value of EUS in Staging for Ampullary Cancer

In this first Vietnamese single-center series, EUS-guided fine-needle biopsy with MOSE achieved high diagnostic accuracy and an excellent safety profile in patients with suspected ampullary cancer managed at a tertiary oncology hospital. These findings support EUS-FNB as the preferred pre-operative tissue acquisition modality within the diagnostic algorithm for ampullary lesions, providing reliable histological confirmation to guide endoscopic or surgical treatment.