Fig. 4

Pathology specimen. a Gross cross-section of the pancreatic head, showing a tumor lesion (solid line) pervading a white lesion with obscure margins (dotted line) and the lumen of the duodenal papillary common channel. b Mid-magnification image (HE staining ×40) of the white lesion (dots in a). Atrophic pancreatic tissues with fibrogenesis and inflammatory cell infiltration. c Low-magnification image (HE staining ×12.5) of the duodenal papillary common channel (solid line in a). In the sphincter of Oddi, a papillotubular tumor pervading the lumen was observed (arrowhead). A mucinous nodular lesion (arrow) was found in the stroma, with transiting images of the tumor (double circle). d High-magnification image (HE staining ×100) of the arrowhead in c. Hyperplasia of tumor cells with findings of papillotubular growth, IAPN, and low-to-high-grade dysplastic adenocarcinoma. e High-magnification image (HE staining ×100) of the arrow in c. The lesion formed multiple neoplastic mucinous nodes, indicating findings of mucinous carcinoma derived from IAPN. f Mucinous adenocarcinoma infiltrating to the parenchyma of the fibrotic pancreas (HE staining ×40). Mucinous adenocarcinoma (arrowhead) was infiltrating to the parenchyma of the pancreas (double circle). The pancreatic parenchyma was excessively atrophic with the inflammatory cell infiltration