Endoscopic ultrasound-guided fine-needle aspiration value in suspected autoimmune pancreatitis malignancy diagnosis

Histopathology examination is important for diagnosing autoimmune pancreatitis (AIP), which is suspected to be pancreatic cancer based on imaging findings. Although the validity of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in the diagnosis of AIP is still debated globally, this study aimed to evaluate the efficacy of EUS-FNA in the diagnosis of AIP with suspected pancreatic cancer.

From January 2021 to June 2024, 30 AIP patients with radiographically diagnosed pancreatic cancer were enrolled and underwent EUS-FNA. Sex, age, symptoms, CA199, serum immunoglobulin G4 (IgG4), and treatment outcome were included. Tissue sampling conditions, puncture sites, storiform fibrosis, CD38- and IgG4-positive plasma cell counts, and obliterans phlebitis were evaluated.

Thirty patients, 24 males and six females, with an average age of 60.53 ± 11.72 years (32-79 years), were included in the study. Thirty patients had their serum IgG4 and CA199 levels tested. Tissue samples containing ≥10 were obtained from 19 (63.33%) patients. CD38+ plasma cell infiltration and laminar fibrosis were detected in 22 (73.33%) and 10 (33.33%) patients. According to the International Consensus Diagnostic Criteria ( ICDC), 12 patients had histopathological levels of Grade 1, 15 of Grade 2, and three patients could not be classified. The accuracy, sensitivity, and specificity of EUS-FNA in diagnosing AIP with suspected pancreatic cancer on imaging were 96.66% (29/30), 96.42% (27/28), and 100% (2/2), respectively. The area under the curve value of EUS-FNA for patients with AIP who were radiologically suspected of having pancreatic cancer was 0.957.

Approximately 90% of patients with EUS-FNA results are diagnosed with an ICDC level of 2 or higher. Our results suggest that for cases where malignant tumors are suspected after imaging or cannot be ruled out, obtaining pancreatic tissue through EUS-FNA puncture for pathological diagnosis is recommended.