Role of Endoscopic Ultrasonography-Guided Fine Needle Aspiration/Biopsy in the Diagnosis of Autoimmune Pancreatitis

Abstract

Type 1 autoimmune pancreatitis (AIP) is histologically characterized by lymphoplasmacytic sclerosing pancreatitis (LPSP). Recently, the diagnostic yield of endoscopic ultrasonography-guided fine needle aspiration/biopsy (EUS-FNA/B) for AIP has been reported. However, its role in the diagnostic flow of AIP is not fully elucidated. We retrospectively reviewed 53 consecutive patients who were suspected with AIP and underwent EUS-FNA/B. We evaluated the contribution of EUS-FNA/B to the diagnosis of AIP before considering response to steroid therapy among patients with diffuse enlargement of the pancreas and those with focal enlargement, respectively. Twenty-two patients showed diffuse pancreatic enlargement and 31 showed focal enlargement. The final diagnosis was definitive AIP in 32 patients, probable AIP in 2, possible AIP in 1, and mass-forming focal pancreatitis in 18. There was no change in diagnosis after EUS-FNA/B among patients with diffuse pancreatic enlargement, while diagnosis changed in 38.7% (12/31) among those with focal enlargement—there was a probable to definitive diagnosis in 4 patients, unspecified to definitive in 3, and unspecified to probable in 5. EUS-FNB provided a significantly higher sensitivity for typical pathological findings of LPSP than EUS-FNA, and 10 patients were diagnosed as pathologically definitive AIP by EUS-FNB, though none were by EUS-FNA (p = 0.002). EUS-FNA/B was useful in the diagnosis of focal type AIP, and steroid therapy could be introduced after the diagnosis was confirmed. Meanwhile, EUS-FNA/B provided no contribution to diagnosis of diffuse type AIP. EUS-FNB showed a higher diagnostic yield than FNA.

Recent advances in the management of autoimmune pancreatitis in the era of artificial intelligence

“…In the last decade, the proportion of pancreatic samples obtained by EUS has significantly increased from 48% in 2007 to 86% in 2016 in Japan[ 7 ]. Several studies nevertheless report the difficulty in diagnosing AIP with EUS-FNA (sensitivity of 43%-60%) and obtaining a sufficient amount of fibrotic tissue[ 11 - 16 ], which explains the shift toward EUS-FNB[ 20 , 21 ]. A Japanese study on 44 AIP patients obtained an adequate histological sample in 93% of cases, leading to a confirmed diagnosis of AIP in 43% of cases, a diagnosis of idiopathic chronic pancreatitis (CP) in 50% of cases, and no false positives for pancreatic cancer[ 22 ].…”

Biopsy diagnosis of type 1 autoimmune pancreatitis: Does it bring a conclusion or confusion?

“…24,25 In the 2010s, several groups -notably from Japanattempted to develop a method for making a histological diagnosis of AIP by EUS-FNA, [26][27][28][29][30][31][32][33][34] and the use of EUS-FNB has more recently become common. [35][36][37][38][39][40] Details of these data have been discussed in systematic reviews and meta-analyses, [41][42][43] and I will not repeat the discussion here. Instead, I will focus on the histological diagnoses of the studies, which vary among the reports (Table 1).…”

“…In the 2010s, several groups — notably from Japan — attempted to develop a method for making a histological diagnosis of AIP by EUS‐FNA, 26–34 and the use of EUS‐FNB has more recently become common 35–40 . Details of these data have been discussed in systematic reviews and meta‐analyses, 41–43 and I will not repeat the discussion here.…”

Utility of Endoscopic Ultrasound-Guided Fine-Needle Aspiration and Biopsy for Histological Diagnosis of Type 2 Autoimmune Pancreatitis

“…In fact, the diagnosis of type 1 AIP using EUS-FNB has been reported in many studies, suggesting that EUS-FNAB is useful for the diagnosis of type 1 AIP [ 13 , 14 , 15 , 16 , 17 ]. In contrast, diagnosis of type 2 AIP using EUS-FNAB has been reported in only a few studies.…”