Pancreatic solid focal lesions: autoimmune pancreatitis or pancreatic cancer?
|Fakulta / Pracoviště MU|
|Popis||Purpose: The diagnosis of pancreatic ductal adenocarcinoma (PDAC) in treatable early stages continues to be challenging. Autoimmune pancreatitis (AIP) can, similarly to PDAC, present as a focal mass and, therefore, an accurate differential diagnosis is of crucial importance. Raised serum immunoglobulin G4 (IgG4) levels, over the twice the normal value, are considered to be one of the significant diagnostic features of type 1 AIP. However, IgG4 can also be increased in patients with PDAC, but levels usually do not exceed twice the normal value. Materials and methods: In the years 2012 - 2018, IgG4 serum levels were examined in 117 patients with histologically confirmed PDAC. Histological resection specimens or bioptic specimens were taken from the pancreatic lesions of patients with both PDAC and an elevated IgG4 level (above 135mg/dL). These were then tested for the presence of IgG4 and plasmocytes in the pancreatic tissue, and changes characteristic for type 1 AIP were also searched for. Results: In 14/117 PDAC patients (11.9 %) the plasmatic IgG4 levels were higher than 135 mg/dL. In 2 patients (1.7 %) the serum IgG4 levels were more than double the normal value, and thus suggestive of AIP according to the guidelines. Of these two patients - one of them met the histological criteria for diagnosis of AIP in the simultaneous presence of PDAC. Conclusions: Differentiating AIP from PDAC can be sometimes problematic since these diseases can both present as focal pancreatic mass/ lesions. IgG4 has been considered useful for AIP diagnosis, however, IgG4 levels can be slightly elevated, as is the case with PDAC. IgG4 levels of over the twice of the upper limit are rare among PDAC patients (1.7% in our study group). However, cases of simultaneous presentation of PDAC and AIP have been documented and should not be neglected. Therefore, targeted biopsy of the pancreas is the method of choice in cases suspected of being a focal form of AIP, and we recommend it over other modalities, such as e.g. response to steroid therapy.|