The Role of EUS-Guided FNA and FNB in Autoimmune Pancreatitis

Abstract

Autoimmune pancreatitis (AIP) is an increasingly recognized disease classified into two different subtypes based on histology. According to the International Diagnostic Criteria (ICDC), the diagnosis is achieved using a combination of different criteria. In patients presenting with a typical imaging appearance, the diagnosis may be straightforward, and steroid treatment is recommended, even without histological confirmation. In patients with atypical imaging or mass-forming appearance, the differential diagnosis with pancreatic cancer is challenging and crucial for treatment strategy. Endoscopic ultrasound (EUS)-guided tissue acquisition has been proposed to achieve a histological diagnosis. Fine-needle aspiration (FNA) was first proposed to aspirate cells from pancreatic lesions. Despite excellent results in terms of sensitivity for pancreatic cancer, the data are disappointing regarding the diagnosis of AIP. The recent development of new needles allowing fine-needle biopsy (FNB) has been associated with improved diagnostic accuracy based on preserving the tissue architecture, which is necessary to detect the typical histological features of AIP. However, the published literature on the role of EUS-guided FNA and FNB is limited and mainly focused on type 1 AIP. The present study aimed to review the available literature on the role of EUS-guided FNA and FNB in the diagnosis of AIP.

IgG4-related autoimmune pancreatitis-like mass-forming lesion on a background of immune checkpoint inhibitor immunotherapy

“…3 A recent review has highlighted the high sensitivity of pancreatic EUS FNA for diagnosing malignancy, in contrast to the high rate of inconclusive diagnoses in cases of AIP, leading to a significant proportion of inappropriate surgical resections even at experienced centres. 9 Recently, studies have suggested an autoimmune mechanism in the development of pancreatitis following administration of immunotherapy. 1 In our case, the patient received nivolumab, a human IgG4 monoclonal antibody that works as an ICI via blockade of programed death receptor 1 (PD-1).…”

Intraductal Papillary Mucinous Carcinoma With Type 1 Autoimmune Pancreatitis

“…It is reported that it is not always easy to obtain a definitive diagnosis of AIP because it is sometimes difficult to collect the amount of stain required for EUS-FNA or there might be a problem regarding the immunohistochemical stain. 8 Of all the patients described in Table 1, only our patient was successfully diagnosed with type 1 AIP preoperatively. Accumulation of cases to clarify the relationship between IPMN and type 1 AIP is expected.…”

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

“…Regardless of needle type, sufficient tissue samples with HPF > 10 were obtained in 80.0% of cases. Several studies have shown the usefulness of EUS-FNB with a 22-G needle for the histological diagnosis of AIP [ 14 , 19 , 29 , 30 , 31 ]. In this study, a 22-G needle was also used in 9 out of 10 cases, and sufficient tissue amounts were collected.…”