Introduction
Diagnosing focal or segmental autoimmune pancreatitis (AIP) remains challenging, particularly in differentiating it from pancreatic malignancy. Histological confirmation is a key component of the International Consensus Diagnostic Criteria (ICDC), yet tissue acquisition remains limited with conventional techniques. End-cutting needles used in EUS-guided fine-needle biopsy (EUS-FNB) may improve diagnostic performance.
Aims & Methods
To evaluate the diagnostic contribution of EUS-FNB using end-cutting needles in suspected focal or segmental AIP.
We conducted a prospective study at the Department of Gastroenterology and Hepatology, Mohammed VI University Hospital, Marrakech, including consecutive adult patients undergoing EUS-FNB for suspected focal or segmental AIP between 2021 and 2025.
Patients with prior AIP diagnosis or recent steroid therapy were excluded. EUS-FNB was performed using end-cutting needles, with at least two passes per lesion. Histological samples were classified according to ICDC levels.
The primary endpoint was the rate of diagnostic upgrading after EUS-FNB. Secondary endpoints included detection of malignancy and procedural safety.
Results
A total of 26 patients were included (69% male; mean age 59.6 ± 13.8 years), including 17 focal and 9 segmental forms. Jaundice was the most frequent presenting symptom (46%).
EUS-FNB achieved a high sample adequacy rate (92.3%). Pancreatic malignancy was diagnosed in 3 patients (11.5%), emphasizing the importance of histological confirmation.
Among patients with suspected AIP, EUS-FNB provided histological level 1 in 13 cases and level 2 in 5 cases, resulting in a definitive diagnosis of AIP in 66.7% of evaluable cases. In the remaining cases, non-specific inflammation was observed, with subsequent classification as probable AIP based on clinico-radiological criteria.
Sensitivity and specificity for AIP diagnosis were 95% and 100%, respectively. No procedure-related adverse events were recorded.
Conclusion
EUS-FNB using end-cutting needles significantly improves histological diagnosis of focal and segmental AIP in a real-world setting. This approach allows reliable differentiation from malignancy and supports early therapeutic decision-making before steroid initiation.
References
- Okazaki K, Chari ST, Frulloni L, et al. International consensus for the diagnosis of autoimmune pancreatitis. Pancreas. 2011;40(3):352–358.
- van Riet PA, Larghi A, Attili F, et al. Endoscopic ultrasound-guided fine-needle biopsy versus fine-needle aspiration for pancreatic lesions: a multicenter randomized trial. Gastrointest Endosc. 2021;93(3):629–637.
- Iwashita T, Yasuda I, Mukai T, et al. Macroscopic on-site evaluation improves adequacy of EUS-FNB specimens. J Gastroenterol Hepatol. 2022;37(2):298–304.