Clinical and Immunopathologic Profile of Mexican Patients with IgG4 Autoimmune Pancreatitis

Autoimmune pancreatitis is part of the spectrum of IgG4-associated diseases. Its diagnostic criteria and histological subtypes have been formally proposed recently and although based on current data it has been suggested that there are differences in clinical presentation among populations, more research is needed to properly establish if this heterogeneity exists. In this paper, we describe 15 cases of autoimmune pancreatitis diagnosed at a Mexican centre of reference, all of them associated to the lymphoplasmocytic sclerosing pancreatitis variant. The mean age at the onset of symptoms was 47.5 ± 14.4 years, and 53% of patients were male. The main manifestations were weight loss (87%), obstructive jaundice (53%), and acute (27%) and chronic (27%) pancreatitis. Only 20% of patients had high IgG4 serum levels at the time of diagnosis. All patients receiving prednisone responded favourably, both in their pancreatic and extrapancreatic manifestations. Clinical manifestations of Mexican patients showed certain differences with respect to those usually reported. 1. Introduction Autoimmune pancreatitis has travelled a relatively short way from its first description by Sarles et al. in 1961 [1] to the formal suggestion of the very concept of autoimmune pancreatitis by Yoshida et al. in 1995 [2], and its subsequent inclusion in a new group of diseases with systemic involvement associated with an increase in serum IgG4 levels, after the depiction by Kamisawa et al. [3]. Most descriptions have, up to now, been done on Asian patients, even though there have been descriptions of patients in other geographical areas [4, 5]. In spite of the scant information available, mainly due to the few reported cases of the disease and its aforementioned “short” history, it is possible to assert that there are some differences in the clinical presentation of patients of different ethnicities. In conjunction with the scarcity of available information, there is the added problem that until recently, there is a lack of universally recognised criteria for the diagnosis of the disease. Asian, European, and North American consensus have so far been published [6–8] and most centers use distinct criteria, making difficult to establish comparison among patients in whom the diagnosis was made at different geographical areas. Recently, an international panel of experts met to develop the International Consensus Diagnostic Criteria for Autoimmune Pancreatitis to favor the worldwide recognition of the illness [9]. In this consensus, emphasis is placed on the advantages of classifying