Inflammatory and tumor-like lesions of the pancreas

Abstract

Inflammatory/tumor-like lesions of the pancreas represent a heterogeneous group of diseases that can variably involve the pancreatic gland determining different signs and symptoms. In the category of inflammatory/tumor-like lesions of the pancreas, the most important entities are represented by chronic pancreatitis, which includes alcoholic, obstructive and hereditary pancreatitis, paraduodenal (groove) pancreatitis, autoimmune pancreatitis, lymphoepithelial cyst, pancreatic hamartoma and intrapancreatic accessory spleen. An in-depth knowledge of such diseases is essential, since they can cause severe morbidity and may represent a potential life-threatening risk for patients. Furthermore, in some cases the differential diagnosis with malignant tumors may be challenging. Herein we provide a general overview of all these categories, with the specific aim of highlighting their most important clinic-pathological hallmarks to be used in routine diagnostic activities and clinical practice.

Keywords: autoimmune pancreatitis; chronic pancreatitis; groove; pancreatic pathology; paraduodenal pancreatitis.

Figure 1.

Paradigmatic images of PGP and CP. PGP, solid variant: marked expansion of the groove area (asterisk) and marginal involvement of the pancreatic parenchyma and of choledocus (black arrow) (A); PGP, cystic variant: diffuse presence of cysts and extensive pancreatitis of the pancreatic parenchyma (B); CP with intraductal calculi (asterisk: coledochus, black arrow: Wirsung’s duct) (C); Macroscopic translucent/pearly appearance of CP can be better appreciated on fresh tissues (asterisk: coledochus, black arrow: Wirsung’s duct) (D).

Figure 2.

Important histological patterns of chronic pancreatitis. (A) Marked fibrosis with loss of normal pancreatic parenchyma (original magnification 4X); (B) calcification in pancreatic duct with focal squamous metaplasia of a duct (original magnification 10X); (C) calcific plugs in pancreatic duct with ductal changes (original magnification 10X); (D) pancreatic pseudocyst: the lack of epithelial lining is evident (original magnification 4X).

Figure 3.

The histological appearance of paraduodenal groove pancreatitis is here shown. The cystic region usually includes multiple cysts lined by ductal epithelium (original magnification 2X).

Figure 4.

Key histological and immunohistochemical patterns of autoimmune pancreatitis. (A) Marked inflammatory infiltrate is typically centered around pancreatic ducts (original magnification 10X); (B) dense inflammatory infiltrate with secondary pancreatic parenchyma is encountered in late-stage autoimmune pancraetitis (original magnification 4X); (C) immunohistochemical analysis for CD138 highlights a diffuse infiltration by plasma cells (original magnification 4X); (D) immunohistochemical analysis for IgG4 indicates that a high number of plasma cells are also positive for IgG4 (original magnification 4X).

Figure 5.

Typical microscopic appearance of lymphoepithelial cysts (A, B; original magnification A: 2X, B: 10X), of intrapancreatic accessory spleen (C, D; original magnification C:2X, D: 10X), and of pancreatic hamartomas (E, F; original magnification E:1X, F: 20X). Notably, the pancreatic hamartoma shows a ductal predominance (E, F).