胰腺导管内乳头状瘤

北大医院放射科 程晓悦Patient, female, 79-years old， with tumors in the body of the pancreas founded by the Ultrasound。CT shows that: Pancreatic atrophy；there were multiple round hypo-dense lesions in the neck and body of the pancreas，with clear boundaries and no enhancement in the enhanced CT scan；Some lesions had a little strip separators and parts of the lesions were close to the main pancreatic duct； The pancreatic duct was dilated.定义 胰腺导管内乳头状黏液肿瘤 (intraductal papillary mucinous tumor， IPMT)是一种特殊的胰腺囊腺瘤，可分泌大量黏液导致主胰管全程扩张，十二指肠乳头部开口由于黏液流过而扩大。 相对少见的胰腺肿瘤 。 1982年由 Ohashi首先报道，此后陆续有一些报道，但对该病命名不同，如产黏液 癌、导管内癌、导管产黏液肿瘤等。 1990年 WHO将其统一称为 IPMN（ intraductal papillary mucinous neoplasms ）。特点 IPMT多见于 60岁一 70岁老年人，男性多于女性，而临床症状缺乏特异性，主要表现为反复上腹痛、乏力、纳差、消瘦及慢性胰腺炎、 2型糖尿病等。 特点：1、胰管内大量黏液潴留；2、乏特乳头部开口由于黏液流过而扩大；3、主要在主胰管发展和播散；4、很少有浸润的倾向；5、手术切除率高及预后良好等特点。病理IPMT的基本病理改变是胰管内分泌粘蛋白的上皮细胞乳头状增生，分泌大量黏液样物质并潴留于腺管内造成胰管扩张。 组织学上将其分为导管内乳头状黏液瘤、交界性和导管内乳头状黏液癌。 根据肿瘤发生部位，通常把 IPMT分为 3型：主胰管型，肿瘤存在于主胰管并其扩张；分支胰管型，肿瘤位于分支胰管内；混合型，肿瘤既存在与主胰管又存在于分支胰管。(a)CT scan of the individual D: presence of a 20 mm BD-IPMN in the body of the pancreas (white arrow). Main-duct intraductal papillary mucinous tumor (IPMT) with markedly dilated pancreatic duct with papillary projections that enhance on contrast-enhanced CTMRCP ： a cystic lesion in the uncinate process of the pancreas(asterisk) and a communicating branch duct (arrow) between the cystand the normal caliber main pancreatic duct. These findings are characteristic of a branch duct intraductal papillary mucinous neoplasm and this lesion has been stable on follow up MRCP examinations for 3 years.ERCP shows opacification of the cystic lesion and the focally dilated main pancreatic duct near the cystic lesion.影像表现 USCTMRIERCPMRCP。 MRI在其分型方面优于 CT。 IPMT影像上主要表现为单房或多房囊性肿瘤，常伴有分隔及壁结节；增强扫描可见分隔及壁结节轻 -中度强化。 分支管型好发于胰腺钩突，病变呈分叶状或葡萄状由多个直径 12 cm 的小囊聚合而成。少数也可融合为单一较大囊性改变，其内伴有索条状分隔。 主胰管及分支胰管不同程度的扩张，在 CT重建及 MRCP中，可清晰显示病变与扩张腺管的关系，直接显示病变与扩张的胰管相通有利于本病的诊断与鉴别诊断。 此外， IPMT常伴有胰腺的萎缩。C, Helical CT scan shows communication (straight arrow) between dilated main pancreatic duct (curved arrow) and cystic lesion (arrowhead).D, Histologic specimen shows communication (straight arrow) between main pancreatic duct (curved arrow ) and cystic lesion (arrowhead) covered by papillary epithelium smaller than 1 mm. (H and E, 1)1. Natural history (1) Median age 6168 years (2) Patients with malignant IPMNs are about 5 years older as compared with those with benign IPMNs2. Clinical symptoms (1) Obstructive jaundice(2) Epigastric pain(3) Weight loss(4) Diabetes3. Imaging 1) The main duct and combined types of IPMNs have a higher risk of associated alignancy as compared with the branch-duct type 2) Marked dilatation of the main pancreatic duct is associated with malignancy in IPMNs 3) Presence of thickening mural, large nodules or a solid mass is suggestive of malignancy in IPMNs 4) IPMNs with common bile duct obstruction may indicate the occurrence of invasive cancer 5) IPMNs invading adjacent structures, such as the duodenum, major vascular structures 6) Lymph node metastases, liver metastases or peritoneal deposits4. FNAC/B（细针穿刺活检） (1) Cytological examination of pancreatic juice (presence of malignant cells) identified as an independent predictor of invasive IPMNs (2) MUC1 expressionDiagnosis of malignant or invasive IPMNs.CT检查对术前区分良、恶性 IPMT Chiu 等： CT片上发现主胰管明显扩张、存在有附壁结节、厚的隔膜以及胰周界限不清等指标均为判定恶性 IPMT的独立依据。 Kawai 等：当肿瘤大小超过 30 mm、附壁结节超过 5 mm是诊断 IPMT为恶性的一个重要依据。 Sugiyama 等：恶性 IPMT的主胰管直径扩张等于或大于 7 mm可能提示为恶性。 Kawamoto等：分析了 46位 IPMN患者的胰腺 CT资料，发现主胰管扩张、主胰管受累、弥漫性或多发性病灶、壁内结节、肿瘤大小、胰管阻塞等都可作为判断肿瘤恶性行为的指标。Axial T2-weighted (A) and subtraction (post-contrast minus precontrast)(B) images at the level of the pancreas ： marked enlargementof the main pancreatic duct (arrowheads) with intraluminal enhancingpapillary projections (arrows). Main duct intraductal papillary mucinous neoplasm with in situ carcinoma was confirmed at histopathology after total pancreatectomy.Multiple renal cysts (asterisks).Fig. 3. A 65-year-old woman with malignant IPMT with 12mm papillary neoplasms.a) CT ： shows papillary neoplasms as slightly heterogeneous soft tissue in the dilated main pancreatic duct.b) Contrast-enhanced MR image : shows low signal intensity of the dilated main pancreatic duct andhypersignal intensity of papillary projections. c)MRCP: shows papillary neoplasmsas low signal intense areas in high signal intensity of the main pancreatic duct.CT： the head of the pancreas shows a cystic lesion (asterisk) in the uncinate process of the pancreas with a hypo-attenuating area (arrow) in the adjacent pancreatic parenchyma. Note the intrahepatic biliary dilatation (arrowheads)due to obstruction of the common bile duct (not shown) by the infiltrating mass.Invasive pancreatic adenocarcinoma arising from an intraductal papillary mucinous neoplasm was confirmed at pathology after a Whipple procedure. GB: Gallbladder.Malignant IPMT of the pancreatic tail with invasion and occlusion of the splenic artery behind the pancreatic taila) Helical CT scan shows marked dilation of the main pancreatic duct and branch ducts. The dilated papilla bulges into the duodenal lumen (arrow). There is a ancreatoduodenalfistula (arrowhead).b) Contrast-enhanced MR image (TR/TE, 130/4.1) shows low signal intensity within the dilated main pancreatic duct and branch ducts. Bulging of the papilla into duodenal lumen (arrow) and a pancreatoduodenal fistula (arrowhead) are seen.鉴别诊断