PMC5342982_01
Preoperative images. a) Enhanced abdominal computed tomography showing polycystic lesions in the pancreatic tail (arrows). b) The cystic lesion in the pancreas appearing as a low-intensity area on T1-weighted magnetic resonance imaging (arrow). c) Magnetic resonance cholangiopancreatography showing obstruction of the main pancreatic duct in the proximity of the cystic lesions (arrow). d) Endoscopic ultrasonography showing several nodules (maximum diameter, 10 mm) in the cystic lesion (arrow) in the pancreas.
gr1.jpg
PMC5342982_01_gr1.jpg
fig0005
The CT showed polycystic lesions (maximum diameter, 5 cm) in the pancreatic tail and no indications of chronic pancreatitis, such as parenchymal atrophy or calcification (Fig. 1a). MRI, respectively (Fig. 1b). Magnetic resonance cholangiopancreatography revealed obstruction of the main pancreatic duct in the proximity of the cystic lesions (Fig. 1c). Intracystic nodules (maximum diameter, 10 mm) were detected using endoscopic ultrasonography (Fig. 1d).
Resected specimen and findings of cholesterol granuloma. a) It was impossible to distinguish the cholesterol granuloma from a malignant neoplasm based on macroscopic examination of the resected specimen. b) The cut surface of the cystic lesions showed milky fluid. c) Granulomatous and cystic lesions (arrows) surrounded the main pancreatic duct (*) (H&E, 5x magnification). d) Cholesterol crystals with inflammatory cells and foreign body giant cells were observed (H&E, 40x magnification). H&E: hematoxylin-eosin stain.
gr2.jpg
PMC5342982_01_gr2.jpg
fig0010
On the surface, the resected pancreas showed nodular and cystic changes (Fig. 2a). The cut section revealed cystic lesions containing milky fluid, which was found to contain cholesterol crystals when examined microscopically (Fig. 2b). Histological analysis revealed that the cystic lesion consisted of a dilated main pancreatic duct and cavities of degenerated granulomas containing cholesterol crystals that were surrounded by foreign body giant cells (Fig. 2c and d).
Pathological findings that met the diagnostic criteria of autoimmune pancreatitis. a) Prominent lymphocyte and plasma cell infiltration (H&E, 40x magnification). b) Storiform fibrosis (H&E, 100x magnification). c) Obliterative phlebitis (arrow) (H&E, 40x magnification). d) Immunohistochemical staining for IgG4, showing >10 IgG4-positive plasma cells per high-power field (400x magnification). H&E: hematoxylin-eosin stain.
gr3.jpg
PMC5342982_01_gr3.jpg
fig0015
In addition, the rest of the pancreatic tissue around the lesion showed prominent lymphocyte infiltration, storiform fibrosis, obliterative phlebitis, and IgG4-positive plasma cells, meeting the pathological diagnostic criteria of AIP, as revised by the Japan Pancreas Society in 2011 (Fig. 3).