The quandary of autoimmune pancreatitis and pancreatic ductal adenocarcinoma: A case report and review of IgG4 immunostaining in a cohort of patients receiving neoadjuvant chemotherapy

Harish Lavu,Ornela Dervishaj,Charles J Yeo ,Agnieszka K Witkiewicz

doi:10.5348/ijhpd-2013-10-cr-1

Abstract

ABSTRACT Introduction: Autoimmune pancreatitis (AIP) is an inflammatory disease whose clinical presentation can mimic that of pancreatic ductal adenocarcinoma (PDA). AIP can appear on imaging as a bulky, sausagelike pancreatic mass with biliary and pancreatic ductal obstruction, resembling the classic “double duct sign” appearance of PDA. A definitive preoperative diagnosis of AIP can be difficult because the two diseases (AIP and PDA) are similar in clinical presentation. Recent advances in serum marker evaluation such as IgG4 serum levels and immunostaining techniques have shown some promise in the differentiation of AIP from PDA. Case Report: We report the case of a patient with a preoperative diagnosis of locally advanced PDA who was treated with neoadjuvant gemcitabine based chemotherapy followed by surgical resection, but whose post resection pathology was indicative of AIP and not PDA. To explore the possibility that the pre resection gemcitabinebased chemotherapy had generated a complete pathological response and an inflammatory reaction of IgG4positive plasma cells, we studied the histology features and IgG4 plasma cell immunostaining characteristics of the pathology specimens of 14 patients with a diagnosis of PDAwho were treated with neoadjuvant chemotherapy and surgical resection at our institution. Conclusion: Our results indicate that none of the patients treated with neoadjuvant chemotherapy had increased IgG4positive plasma cell immunostaining post operatively, further supporting the diagnosis of AIP and not PDA in our patient.

Highlights

Autoimmune pancreatitis (AIP) is an inflammatory disease whose clinical presentation can mimic that of pancreatic ductal adenocarcinoma (PDA)
Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis characterized by a lymphoplasmacytic infiltrate rich in IgG4positive plasma cells
We present the case of a patient who had a presumptive diagnosis of locally advanced pancreatic ductal adenocarcinoma (PDA) and received neoadjuvant gemcitabine based chemotherapy and subsequent surgical resection

Summary

INTRODUCTION

Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis characterized by a lymphoplasmacytic infiltrate rich in IgG4positive plasma cells It was formally recognized in 1995 when Yoshida et al published a case report of a patient with pancreatitis and the presence of hyperglobulinemia [1]. Given the similarity in clinical presentation between AIP and PDA, a number of published studies have offered criteria to allow for a more accurate differentiation between the two diseases [6, 9] (Table 1). To study the possibility that neoadjuvant chemotherapy elicited a complete tumor response with a IgG4positive plasma cell infiltrate, we immunostained with IgG4 antibody fourteen other cases of PDA that were treated preoperatively with either gemcitabine alone or another chemotherapeutic agent and were surgically resected at our institution. None of the patients had histologic features of AIP or a high number of IgG4 positive plasma cells on analysis of their resection specimens (figure 4)

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DISCUSSION

CONCLUSION