[Visually Isoattenuating Pancreatic Acinar Cell Carcinoma:Report of One Case]

Acinar cell carcinoma of pancreas(ACCP)is a rare pancreatic exocrine tumor that accounts for about 1% of pancreatic tumors. The typical imaging manifestations of ACCP are as follows:(1)the tumor is large in volume,partially or completely exophytic;(2)complete or incomplete capsule is visible with thin linear enhancement;(3)CT density and MRI signal:plain CT images reveals that the tumors have similar or slightly hypodense densities relative to the adjacent normal pancreas,the solid part of ACCP has low to intermediate signal intensity on T1WI and intermediate to high signal intensity on T2WI compared with the surrounding normal pancreas;(4)pattern of enhancement:tumors exhibit heterogeneous enhancement and it is less than that in the surrounding normal pancreas;(5)fissure-like,swirling necrosis that may be a characteristic change of tumor;(6)pancreatic and biliary duct dilatation is rare;(7)adjacent organs and blood vessels around the pancreas may be invaded;(8)distant metastasis of liver and other parts may be observed;(9)PET-CT shows high FDG uptake. An ACCP patient with atypical imaging manifestations was treated in Peking Union Medical College Hospital from November 2015 to August 2017. The lesion manifested iso-enhancement and many imaging examinations failed to find the tumor. The patient ultimately underwent surgery and diagnosed as ACCP by pathology.