Autoimmune pancreatitis: A critical analysis of the surgical experience in an era of modern diagnostics

Abstract

Presenter: Michael Wright MS | Johns Hopkins University School of Medicine Background: Autoimmune pancreatitis (AIP) is a rare disease that remains a diagnostic challenge. The radiographic appearance can mimic malignant pancreatic neoplasms and biopsies are frequently non-diagnostic. While non-operative management is favored as an initial approach, a cohort still undergoes pancreatectomy due to diagnostic uncertainty. The aim of the current study was to perform a critical analysis of the surgical experience of managing AIP in an era of modern diagnostics, and compare these patients with those who were managed conservatively. Methods: Two prospectively maintained databases was used to identify patients with AIP who were either managed conservatively or those who underwent pancreatectomy and were found to have AIP. Data on preoperative diagnostics, clinicopathologic characteristics, and patient outcomes were critically examined. Results: A total of 88 patients with AIP were included in the study, of whom 56 (63.6%) underwent resection of disease and 32 (36.4%) were managed conservatively. Patients who underwent resection were significantly older (mean age: 61.9 vs. 53.6 years, p=0.014), and were more likely to present with symptoms typically associated with pancreatic malignancies including jaundice (64.3% vs. 18.1%, p<0.001) and weight loss (53.6% vs. 15.6%, p=0.005). Furthermore, at presentation the resected cohort had a significantly higher CA19-9 (median CA19-9: 40.0 vs. 18.6 U/mL, p=0.034), and was less likely to have elevated IgG4 (26.1% vs. 50.0%, p<0.001). The most frequent presumed diagnosis after radiological work up in the resected cohort was PDAC (39.3%) as compared to AIP in the conservatively managed cohort (68.8%). Similarly, cytopathological review was most frequently non-diagnostic in the surgical cohort (51.4%) as compared to suggestive of AIP in the comparison group (63.6%). At long-term follow up, of the resected cohort, 13 (23.2%) developed new onset diabetes and 10 (17.9%) had developed pancreatic insufficiency. All patients achieved resolution of their symptoms, however nine patients (28.1%) in the conservatively managed cohort experienced relapse as compared to six patients (10.7%) in the resected cohort. Conclusion: AIP remains a diagnostic challenge and there is a dire need for improved diagnostics and biomarkers for accurate diagnosis of these patients. The most frequent reason for surgical resection is concern for malignancy. Importantly, CA19-9 tumor marker elevations were noted more commonly than elevated IgG4 in our surgical cohort suggesting that this lab profile is suboptimal for this population. Unless preoperative diagnostic certainty can be improved, there will remain a population of patients with AIP who continue to undergo surgical resection due to concern for malignancy.