Fine Needle Aspirate of Autoimmune Pancreatitis (Lymphoplasmacytic Sclerosing Pancreatitis): Cytomorphologic Characteristics and Clinical Correlates

Abstract

Objective: Autoimmune pancreatitis (AIP) is an inflammatory, IgG4-associated condition that often overlaps clinically and radiographically with pancreatic ductal adenocarcinoma. We reviewed our institutional experience with fine needle aspiration (FNA) cytology in patients subsequently diagnosed with AIP. Study Design: A retrospective review was conducted of FNA results correlating to all surgical pancreatic specimens diagnosed as AIP or lymphoplasmacytic sclerosing pancreatitis from 1984 to 2011. Results: AIP was diagnosed in 15 cases by surgical resection and in 2 by combined clinical findings and nondiagnostic biopsies. Of 20 aspirates from 17 patients, 1 was diagnosed as malignant, 1 as neoplasm (mucinous), 10 as atypical, 5 as benign, and 3 as scant or nondiagnostic. Of the 10 aspirates diagnosed as atypical, 1 was suspicious for malignancy, 1 could not exclude neuroendocrine neoplasm, 1 was markedly atypical, and 7 demonstrated scattered ductal atypia. Common morphologic features included hypocellularity, focal-to-marked ductal epithelial atypia, fibrous tissue fragments, and a smear background lacking red blood cells. Conclusion: On FNA, AIP most often leads to an ‘atypical’ cytopathologic interpretation and rarely may be diagnosed as adenocarcinoma. Thus, caution is warranted to avoid overdiagnosis on FNA when a mass lesion is reported in a patient with clinical or radiographic suspicion of AIP.

Endoscopic ultrasound‐guided pancreatic fine‐needle aspiration: Potential pitfalls in one institution's experience of 1212 procedures

“…Another well‐documented difficulty is the presence of atypical cells in a background of pancreatitis, especially chronic pancreatitis, which can notoriously mimic pancreatic carcinoma clinically, radiologically, and cytologically. Instead of truly representing neoplastic cells, these atypical epithelial cells can represent mucinous metaplasia, high‐grade PanIN, islet cell hyperplasia/nesidioblastosis, and Brunner cell hyperplasia . As mentioned earlier, because the morphological differences among cells with reactive atypia, high‐grade PanIN, and atypical islet cells in pancreatitis from their neoplastic counterparts can be subtle, a small quantity of the atypical cells may be the only clue of possible reactive changes.…”

How good is fine needle aspiration? What results should you expect?

“…[2930] However, if non-suspected, FNA of pancreatic mass in a context of AIP often leads to atypical cytopathological interpretation but also non-rarely to suspicion for malignant process. [31]…”

Specific MAPK-Associated MicroRNAs in Serum Differentiate Pancreatic Cancer from Autoimmune Pancreatitis

“…In recent years, the use of EUS-FNA has become widespread, and various reports have indicated that it is useful for differentiation between the two diseases [ 25 , 26 ]. However, definitive diagnosis of AIP is still difficult due to the small size of the specimens obtained by EUS-FNA [ 27 , 28 ]. Attempts have been made to improve the rate of PDAC diagnosis by genetic screening using EUS-FNA specimens [ 17 ], but EUS-FNA itself may sometimes be difficult, depending on the part of the lesion sampled and the neighboring bloodstream.…”