There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
Advances in the past two decades have resulted in the recognition of several tumefactive
pancreatic lesions that, on histologic evaluation, show a varying combination of inflammation
and fibrosis. Autoimmune pancreatitis, the prototypic tumefactive pancreatic fibroinflammatory
lesion, is composed of two distinct diseases, type 1 autoimmune pancreatitis and the
less common type 2 autoimmune pancreatitis. Although designated as autoimmune pancreatitis,
the two diseases show little morphologic or pathogenic overlap. In type 1 disease,
subsets of T lymphocytes (type 2 helper T cells, regulatory T cells, and T follicular
helper 2 cells) are hypothesized to drive the inflammatory reaction. The B-cell response
is characterized by an oligoclonal expansion of plasmablasts, with dominant clones
that vary among patients and distinct clones that emerge at the time of relapse. Although
the precise role of IgG4 in this condition remains uncertain, recent studies suggest
that other IgG subclasses (eg, IgG1) may mediate the immune reactions, whereas IgG4
represents a response to dampen excessive inflammation. A recent study of type 2 autoimmune
pancreatitis highlights the role of CXCL8 (alias IL-8), with duct epithelium and infiltrating
T lymphocytes expressing this chemokine; the latter may contribute to the distinct
form of neutrophilic inflammation in this disease. The review also highlights other
forms of mass-forming chronic pancreatitis: follicular pancreatitis, groove pancreatitis,
and those associated with rheumatologic diseases.