胰管内胰腺神经内分泌肿瘤的影像学特征

Imaging features of intraductal pancreatic neuroendocrine tumor

目的探讨胰管内胰腺神经内分泌肿瘤(PNET)的影像学特征。方法采用回顾性描述性研究方法。收集2013年1月至2020年10月海军军医大学第一附属医院(上海长海医院)收治的17例胰管内PNET患者的临床病理资料;男7例,女10例;年龄为(47±13)岁。患者术前行胰腺CT或磁共振成像(MRI)增强检查。观察指标:(1)胰管内PNET的影像学表现包括①CT检查影像学表现。②MRI检查影像学表现。(2)胰管内PNET的治疗与组织病理学检查情况。正态分布的计量资料以x±s表示,计数资料以绝对数表示。结果(1)胰管内PNET的影像学表现。①CT检查影像学表现:17例患者术前均行胰腺CT增强检查,肿瘤位置为胰头部9例、胰颈部5例、胰体尾部3例。17例患者肿瘤长径为(8.7±2.5)mm,范围为5.2~15.5 mm,肿瘤形态均为类圆形。17例患者肿瘤CT检查平扫均呈等密度,增强扫描动脉期明显强化,静脉期和延迟期持续明显强化,强化程度高于周围正常胰腺组织。17例患者肿瘤均位于主胰管扩张的截断处,主胰管形态呈突然截断,无“鸟嘴样”表现。扩张的主胰管内径为(11.4±5.3)mm,范围为4.5~22.5 mm。17例患者肿瘤其他影像学表现,11例胰腺实质萎缩,伴有潴留性囊肿、伴有胆总管扩张、肿瘤钙化各1例,肿瘤均无囊变和出血。②MRI检查影像学表现:17例患者中,14例行胰腺MRI增强检查,其中T1加权成像呈稍低信号、显示不清晰分别为5、9例;T2加权成像呈低信号、稍高信号、显示不清晰分别为5、2、7例。14例患者中,弥散加权成像呈弥散受限9例,无弥散受限5例;增强扫描强化程度高于周围正常胰腺组织9例,增强扫描显示不清晰5例;14例均显示主胰管扩张。(2)胰管内PNET的治疗与组织病理学检查情况:17例患者均行手术治疗,其中行胰十二指肠切除术9例,行胰体尾脾脏切除术4例,行胰腺节段切除术4例。17例患者术后组织病理学检查结果显示:G1级10例、G2级7例,其中G2级伴淋巴结转移1例、G2级伴淋巴结和肝转移1例。17例患者肿瘤大体观:主体生长于胰管内,并阻塞胰管,上游胰管扩张,胰腺腺泡萎缩,纤维组织增生;肿瘤切面呈灰黄色或棕红色,实性,质地中等,与周围组织分界清晰。17例患者肿瘤显微镜下表现:肿瘤大部分位于胰腺导管内,均有周围胰腺实质侵犯,肿瘤细胞呈多边形,核居中,核分裂象罕见,细胞质呈嗜酸性或透明性,肿瘤间质主要为胶原纤维,含丰富毛细血管网。结论胰管内PNET影像学特征为肿瘤体积小、增强后明显强化、阻塞主胰管伴上游主胰管扩张和胰腺实质萎缩。

Objective To explore the imaging features of intraductal pancreatic neuro-endocrine tumor(PNET).Methods The retrospective and descriptive study was conducted.The clinicopathological data of 17 patients with intraductal PNET who were admitted to the First Affiliated Hospital of Naval Medical University(Changhai Hospital of Shanghai)from January 2013 to October 2020 were collected.There were 7 males and 10 females,aged(47±13)years.Preoperative contrast-enhanced computed tomography(CT)or magnetic resonance imaging(MRI)of the pancreas was performed on patients.Observation indicators:(1)imaging features of intraductal PNET,including①imaging features of CT and②imaging features of MRI;(2)treatment and histopathological examination of intraductal PNET.Measurement data with normal distribution were described as Mean±SD and count data were described as absolute numbers.Results(1)Imaging features of intraductal PNET.①Imaging features of CT:17 patients underwent preoperative contrast-enhanced CT of pancreas.There were 9 cases with tumor located in the head of the pancreas,5 cases with tumor located in the neck of the pancreas and 3 cases with tumor located in the body and tail of the pancreas.The tumor diameter of the 17 patients was(8.7±2.5)mm,with a range of 5.2‒15.5 mm.The tumor shape was round-like in the 17 patients.All the 17 patients showed isodensity on plain CT and markedly enhancement in arterial,venous and portal phases on enhanced CT.The degree of enhancement of tumor was higher than surrounding normal pancreatic parenchyma.All tumors of 17 patients were located at the truncation of main pancreatic duct(MPD)dilation,showing abrupt change in caliber of MPD without the"beak sign".The diameter of dilated MPD was(11.4±5.3)mm,with a range of 4.5‒22.5 mm.Other imaging manifestations of the 17 patients included 11 cases with pancreatic parenchymal atrophy,1 case with retention cyst,1 case with choledochal dilation,1 case with calcification,and all cases without cystic degeneration or hemorrhage.②Imaging features of MRI:preoperative contrast-enhanced MRI was performed in 14 patients.Five cases showed slightly low signal but 9 cases showed unclear on T1-weighted imaging.Five cases showed low signal,2 cases showed slightly high signal but 7 cases showed unclear on T2-weighted imaging.Of the 14 patients,9 cases showed diffusion limited on diffusion weighted imaging and 5 cases showed unlimited diffusion.Nine cases showed marked enhancement in tumor higher than in normal pancreatic parenchyma,but 5 cases were unclear on contrast-enhanced MRI.(2)Treatment and histopathological exmination of intraductal PNET:all the 17 patients underwent surgical treatment,including 9 cases with pancreaticoduodenectomy,4 cases with distal pancreatectomy and splenectomy,4 cases with pancreatic segmentectomy.Postoperative histopatho-logical examination results showed 10 cases of G1 and 7 cases of G2,including 1 case of G2 with lymph node metastasis,1 case of G2 with lymph node and liver metastasis.The pathological gross showed that the tumor body was mainly located in the pancreatic duct and blocked the pancreatic duct,with upstream pancreatic dilation.There were pancreatic acinar atrophy and fibrous tissue hyperplasia.The tumor was grayish-yellow or brownish red,solid,medium in texture and well-defined with the surrounding tissues.Microscopically,the tumor of 17 patients was mainly located in the pancreaic duct and invaded into surrounding pancreatic parenchyma.The cells of tumor were polygonal with a central nucleus,but the mitosis was rare.The cytoplasm was eosinophilic or hyaline.The tumor stroma was mainly collagen fiber with abundant capillary network.Conclusions The imaging features of intraductal PNET are small size,marked enhancement on contrast-enhanced CT and MRI.The tumor obstructs the MPD with distal MPD dilation and pancreatic parenchyma atrophy.