IgG4 as a serological marker of autoimmune pancreatitis: the latest news.

After standard laboratory and imaging studies no causes are identified in nearly 30% of chronic pancreatitis. Japanese authors have helped us to decrease the percentage of so-called idiopathic pancreatitis because they have identified a new clinical entity of pancreatitis: the autoimmune pancreatitis [1]. In the past few years, the frequency of new diagnoses of pancreatitis due to this new entity has increased in Japan and in Europe [2] as well as in other Eastern countries [3]. An autoimmune pathogenesis has been proposed because this condition is occasionally associated with antibodies or other autoimmune-associated diseases, such as Sjogren syndrome, primary biliary cirrhosis and inflammatory bowel disease [1, 4, 5, 6]. Idiopathic fibrosclerosing disorders such as primary sclerosing cholangitis, retroperitoneal fibrosis, Riedel thyroiditis and orbital pseudotumors have been also reported, associated with a clinical picture compatible with autoimmune pancreatitis [7, 8]; finally, autoimmune pancreatitis has been hypothesized during the course of sarcoidosis [9]. Autoimmune pancreatitis is characterized by diffuse or focal pancreatic swelling with narrowing of the pancreatic duct and/or common bile duct [10]. The histological hallmark of this type of pancreatitis is lymphoplasmocytic infiltration especially concentrated on the pancreatic ducts [4, 8, 11]. Even if an operation is often carried out as a consequence of a diagnosis of pancreatic cancer, treatment with corticosteroids is often effective [12]; thus, differentiation between autoimmune pancreatitis and pancreatic cancer remains a diagnostic challenge which needs to be resolved in the next few years. The answer to this question came from Kamisawa et al. [13]. In their study, the authors sought to clarify the clinical and radiological features of autoimmune pancreatitis in order to differentiate this disease from pancreatic carcinoma more easily; they studied 17 cases initially suspected of having pancreatic carcinoma and found that the patients were predominantly elderly men who frequently presented with jaundice but without the features of acute pancreatitis. Diffuse enlargement of the pancreas and irregular narrowing of the main pancreatic duct were radiologically characteristic; however, segmental swelling and narrowing were detected in seven and two patients, respectively. In segmental cases, neither atrophy of the distal pancreas nor marked upstream dilation of the distal main pancreatic duct was observed; angiographic abnormalities occurred in 54% of the cases. Stenosis of the bile duct was also present in the vast majority of the patients (94% of the cases). Regarding the serological markers, elevation of serum gamma globulins and IgG along with the presence of …