Solid pancreatic mass: more than just adenocarcinoma

Solid pancreatic mass: more than just adenocarcinoma Poster No.: C-2249 Congress: ECR 2014 Type: Educational Exhibit Authors: A. Loureiro, H. T. Sousa, J. Brito ; Lisboa/PT, Portimão/PT Keywords: Metastases, Cancer, Diagnostic procedure, Ultrasound, MR, CT, Pancreas, Gastrointestinal tract, Abdomen DOI: 10.1594/ecr2014/C-2249 1 2 2 1 2 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 50

Learning objectives To review the imaging findings of pancreatic adenocarcinoma in various imaging modalities. To illustrate solid pancreatic lesions and pseudolesions other than adenocarcinoma. To emphasize imaging features that may allow a differential diagnosis between adenocarcinoma and alternative diagnoses. Background Solid pancreatic lesions are becoming frequent incidental findings, due to increasing number of abdominal imaging procedures and technical advances in imaging modalities. Pancreatic adenocarcinoma accounts for the majority of pancreatic neoplasms. However, several other lesions and pseudolesions can present as solid appearing pancreatic masses. Solid lesions of the pancreas represent a heterogeneous group of entities that can be broadly classified as either neoplastic or nonneoplastic. A variety of imaging modalities are available for assessing these solid lesions, including ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI), endoscopic US, and hybrid nuclear imaging techniques such as single photon emission computed tomography-ct and positron emission tomography-ct, each of which has its own strengths and limitations. Accurate diagnosis can be challenging. The use of a multimodality imaging approach can help to fulfill this task. Page 2 of 50

Fig. 2 References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Findings and procedure details NEOPLASTIC Pancreatic Ductal Adenocarcinoma - 85-95% of pancreatic tumors - 60-80 years old - 2#: 1# - 60%-70% - pancreatic head; 10%-20% - body; 5%-10% - tail; diffuse - 5% - Poor prognosis: 1-year survival rate <20%; 5-year survival rate <5% - Symptoms: Abdominal pain, weight loss, and jaundice Page 3 of 50

- Imaging features: CT - hypovascular tumour; 10% - isoattenuating with no visible mass Important to pay attention to the secondary signs: mass effect, an abnormal convex contour of the pancreas, ductal obstruction, and vascular invasion. MRI - low signal intensity on T1- and T2-weighted (-w) images due to its scirrhous fibrotic nature. US - ill-defined, heterogeneous hypoechoic mass. "double duct sign" - tumors in the pancreatic head may cause dilatation of both the common bile duct (CBD) and the main pancreatic duct (MPD); tumors in the pancreatic body may cause upstream MPD dilatation Atrophy of the pancreas proximal to the tumor (chronic obstruction). Cystic-necrotic degeneration - 8% of cases Fig. 3: Pancreatic ductal adenocarcinoma in a 65-year-old female. Contrast enhanced axial (a) and coronal (b) CT images in pancreatic phase shows a hypovascular illdefined lesion in the pancreatic body. (c) Endoscopic US shows a heterogeneous hypoechoic tumor, with irregular borders. References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Page 4 of 50

Fig. 4: Pancreatic ductal adenocarcinoma in a 58-year-old male. (a) In T2-w image the lesion appears hypointense. (b) Gadolinium enhanced MRI in pancreatic phase reveals a hypovascular mass. (c) MRCP image showing dilatation of the CBD (orange open arrow) and MPD (green open arrow) - the double duct sign. References: Department of Radiology, Hospital Garcia de Orta, EPE; Portugal Page 5 of 50

Fig. 5 References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Pancreatic Neuroendocrine Tumour (PNET) - 1-5% of pancreatic tumours th - 6 decade of life - Sporadic or in association with: MEN 1 Von Hippel-Lindau Neurofibromatosis I Tuberous sclerosis - Single or multiple - Functioning or non-functioning - Risk of malignancy increases with tumour size (>5cm) Page 6 of 50

Table 1 References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal - Imaging features: In contrast-enhanced imaging modalities: avid enhancement during the arterial phase, more rapid and intense than the normal pancreas. During the portal venous phase, tumors may be either hyper-, iso-, or hypoenhancing relative to the normal pancreas. Some tumors may demonstrate atypical delayed enhancement. Although CBD and MPD dilatation may occur with large PNET in the head of the pancreas, dilatation of these ducts is not a common feature of PNET. Metastases to lymph nodes and solid organs such as the liver may have a similar enhancement pattern. 111 In octreotide imaging - sensitivity 90%; specificity 80% for detecting functional PNET (except insulinoma). Page 7 of 50

Fig. 6: PNET in a 71-year-old woman. (a) Axial non-enhanced CT shows an isoattenuating mass in the pancreatic body with a small calcification. (b) Axial postcontrast arterial phase CT image shows avid enhancement by the tumor (arrow). (c) Axial postcontrast portal phase CT image shows that the tumor remains slightly hyperattenuating comparing to the pancreas. References: J. Brito, Portimão/PT Page 8 of 50

Fig. 7: PNET in a 69-year-old woman. Axial non-enhanced CT shows a isoattenuating mass (orange arrow) in the head of the pancreas. (b) Axial postcontrast arterial phase CT image shows a tumor with heterogeneous arterial enhancement (orange arrow). (c) Axial postcontrast late phase CT image shows that the tumor (orange arrow) returns to be isoattenuating to the pancreas. (d) Reformatted curved CT showing dilatation of the MPD (open green arrow). (e) US reveals a hyopoechoic mass (orange arrow) in the head of the pancreas, with dilatation of the MPD (open green arrow). (f) Axial T1w MRI shows a hypointense tumor (orange arrow) in the pancreatic head. (g) Axial T2w image reveals a slightly hyperintense mass (orange arrow) in the head of pancreas. (h) Axial T2-w image fused with diffusion shows restriction to diffusion by the tumor (orange arrow). References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Page 9 of 50

Fig. 8 References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Solid Pseudopapillary Tumor (SPT) - Young women (2 nd th to 4 decade) - Indolent neoplasms - solitary, large tumours, low malignant potential - When in men - older and more aggressive - SPT can be classified into two subgroups - small (<3 cm) and large (>3 cm). - With the widespread use of cross-sectional imaging, small pancreatic tumors are being increasingly detected incidentally on imaging. - Imaging features: CT: 1. Large tumors: well-encapsulated mass with varying solid and cystic components caused by hemorrhagic degeneration. Calcifications and enhancing solid areas may be present at the periphery of the lesion. Small tumors: appear less sharply circumscribed, often unencapsulated, and completely solid without hemorrhage, necrosis or cystic change. Hypoattenuating on unenhanced images, remain hypoattenuating on pancreatic phase, and may show progressive enhancement, becoming isoor slightly hyperattenuating on the late phases. Calcification is less frequent. 2. Page 10 of 50

MRI: 1. Large tumours: well-defined lesion with a mix of high and low signal intensity on T1- and T2-w images. It commonly presents hemorrhagic areas that show high signal intensity on T1-w images and low or inhomogeneous signal intensity on T2-w images. A thick fibrous capsule appears on T2-w images as a discontinuous rim of low signal intensity. Gadolinium-enhanced dynamic MRI shows early peripheral heterogeneous enhancement of the solid portion with progressive fill-in. Small tumors - Solid lesion without hemorrhagic or necrotic areas - high T2 signal intensity and low T1 signal intensity. 2. Table 2 References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Page 11 of 50

Fig. 9: 51-year old woman with solid pseudopapillary tumor of the pancreas. (a) Plain CT reveals coarse calcifications in the pancreatic tail. After intravenous administration of iodine, a solid tumor becomes apparent, which is hypoatenuating in both the pancreatic (b) and portal venous (c) phases. Delayed enhancement is observed in the late phase (d). On T2-w image (e) the tumor is hyperintense relatively to the surrounding pancreas and appears slightly hypointense on T1-w image (f). Endoscopic US (g) shows a heterogeneous hypoechoic tumor, with irregular borders. References: J. Brito, Portimão/PT Page 12 of 50

Fig. 10 References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Lymphoma - Most commonly NHL, B-cell. - Primary pancreatic lymphoma is rare (<1% of pancreatic tumors, <2% of extranodal lymphoma). - Secondary lymphoma of the pancreas is much more common (30% of patients with widespread lymphoma). - 35-75 years; immunocompromised patients. - Better prognosis than adenocarcinoma. - Two morphologic patterns of pancreatic lymphoma are recognized: a focal wellcircumscribed form and a diffuse form. Focal form occurs in the pancreatic head in 80%. Page 13 of 50

- Imaging features: CT - Well-defined, homogeneous low-attenuation masses relative to the enhancing pancreatic parenchyma, with only mild enhancement. Peripancreatic fat stranding and peripancreatic inflammation, if present, is minimal. Pancreatic atrophy and calcifications are not common. MRI - circumscribed and homogeneous low signal lesion on T1-w images; on T2-w images - intermediate signal (slightly higher signal intensity than the pancreas). Diffuse form - diffuse enlargement of the gland with infiltrative tumour (mimicking pancreatitis). Low signal intensity on T1- and T2-w images. Homogeneous contrast enhancement (less than normal parenchyma). Although bile duct obstruction may occur, severe dilatation of the MPD is uncommon. Fig. 11: Focal large cell lymphoma of the pancreas, in a 54 years-old male. Axial (a) and coronal (b) contrast enhanced CT in portal venous phase shows a hypodense ill-defined nodule (orange arrow) in the body of the pancreas. (c) Axial T1-w image shows a hypointense nodule (orange arrow) in the body of the pancreas. (d) In axial T2-w image the tumor is isointense to the pancreas. (e) T1-w image after gadolinium Page 14 of 50

administration shows a hypovascular nodule (yellow arrow) in the pancreatic body. Posterior to the nodule, outside the pancreas but adjacent to it, there are two adenopathies (green open arrow). (f) PET scan shows FDG uptake by the lesion (orange arrow). References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Fig. 12: Diffuse large cell lymphoma of the pancreas, in a 57 years-old male. Axial CT in arterial (a) and portal venous (b) phases shows diffuse enlargement of the entire pancreas with relatively homogeneous enhancement. (c) Coronal contrast enhanced CT image showing a stent in CBD. (d) US image shows a hypoechoic and enlarged pancreas. References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Page 15 of 50

Fig. 13 References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Acinar Cell Carcinoma (ACC) - Acinar cell carcinoma - 1% to 2% of all pancreatic tumors - Acinar origin th th - 5 to 7 decades of life - 2#:1# - Better prognosis than pancreatic ductal adenocarcinoma, worse than neuroendocrine tumor. - Imaging features: Imaging features are variable: often exophytic, hypovascular and wellmarginated on CT and MRI. Internal calcifications can be present. Central hypodensity on CT. Differential diagnosis: Page 16 of 50

1. 2. 3. Adenocarcinoma - usually smaller than ACC, not well defined, locally invasive without calcifications. Neuroendocrine tumor - more hypervascular than ACC. Can be indistinguishable. Solid pseudopapillary tumor - young women. Both tumors are frequently well-marginated encapsulated tumors with solid and cystic areas. SPT tend to be more heterogeneous. Fig. 14: Acinar cell carcinoma in a 58-year-old man. (a) Axial non-enhanced CT shows a isoattenuating mass in the body of the pancreas. (b) Axial T1-w MRI shows a hypointense tumor (orange arrow) in the pancreatic body. (c) Axial T2-w image reveals a hyperintense mass in the body of pancreas (orange arrow). (d) MRCP sequence shows dilatation and tortuosity of the MPD (green open arrow) distal to the mass. (e, f, g) Axial T1-w image, non-enhanced (e), gadolinium enhanced in arterial (f) and delayed (g) phases showing mild heterogeneous enhancement of the lesion with a well defined enhancing capsule (orange arrow). (h) Axial T2-w image fused with diffusion shows restriction to diffusion by the tumour (orange arrow). References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Page 17 of 50

Fig. 15 References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Metastases - 2-5% of all malignant neoplasm of the pancreas - Most common: Renal cell carcinoma; Lung carcinoma; Breast carcinoma; - Colorectal carcinoma; Melanoma - Three patterns: Solitary; Multifocal; Diffuse - Imaging features: US - hypo- or hyperechoic CT - hypo- or isoattenuating (nonenhanced CT). Cystic masses have been reported. Variable contrast enhancement - hypervascular metastases in cases of hypervascular primary malignancy, commonly seen with renal cell carcinoma and melanoma. MRI - low signal intensity on T1-w and high signal intensity on T2-w images. Pancreatic adenocarcinoma generally manifests as a hypoenhancing mass, whereas metastases show either peripheral enhancement (in over 70% of lesions >1.5 cm) or, less commonly, homogeneous enhancement (smaller lesions) Page 18 of 50

Fig. 16: Pancreatic metastases from lung adenocarcinoma in a 61-year-old man. Axial non-enhanced (a) and contrast enhanced in arterial (b) and late (c) phases CT images reveal an ill-defined hypodense and hypovascular lesion (orange arrow) in the body of the pancreas, without significant dilatation of the main pancreatic duct. Additional images reveal multiplicity of pancreatic lesions (d, e) and hypovascular hepatic nodules, corresponding to liver metastases from the same lung adenocarcinoma. References: J. Brito, Portimão/PT Page 19 of 50

Fig. 17: Metastasis to the pancreas from renal cell carcinoma. The patient had a history of left nephrectomy due to renal cell carcinoma. Non-enhanced (a), contrast enhanced in arterial phase (b), and in portal phase (c) CT images showing a wellcircumscribed strongly enhancing mass in the tail of pancreas with a hypodense central area, corresponding to necrotic changes in the nidus of the solid lesion (orange arrow). References: J. Brito, Portimão/PT Page 20 of 50

Fig. 18 References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal NON-NEOPLASTIC Intrapancreatic accessory spleen - Accessory spleen, also referred as splenunculi. - Common congenital defect - 10-30% of population - Intrapancreatic accessory spleens are easily misdiagnosed as PNET because of their hypervascular appearance. - The diagnosis can be confirmed using superparamagnetic iron oxide (SPIO)-enhanced MRI, Levovist (Bayer, Berlin, Germany)-enhanced US and scintigraphy using 99m Tc- 99m labelled sulfur colloid or Tc-labelled heat-damaged red blood cells. The mechanism of these different techniques is essentially the same: trapping of the contrast material by reticuloendothelial cells. - Scintigraphic techniques are the most specific imaging methods for diagnosing ectopic splenic tissue; however, they offer far inferior anatomic resolution compared to CT or MRI. Page 21 of 50

Fig. 19: 64-year-old female with a hypervacular nodule in the tail of the pancreas, that proved to be an intrapancreatic accessory spleen. (a) Axial T2-w images without (a) and with (b) fat suppression demonstrate a mild-to-intermediate hyperintense nodule (orange arrow) in the pancreatic tail, with signal intensity similar to that of the spleen. (c) In axial T1-w image the nodule (orange arrow) is hypointense, similar to the adjacent spleen. (d) Axial T1-w image after gadolinium and (e) arterial phase CT show a hypervascular nodule (orange arrow) in the pancreatic tail that has the same enhancement pattern of the spleen. (f) Endoscopic US image showing an hypoechoic nodule (orange arrow). (g) Histopathology of the surgical specimen confirming intrapancreatic accessory spleen. References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Page 22 of 50

Fig. 20 References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Pseudotumoral pancreatitis - Pancreatitis can manifest as a focal fibroinflammatory mass (common in pancreatic head), mimicking adenocarcinoma. - Inflammation can coexist with adenocarcinoma and adenocarcinoma may arise in longstanding chronic pancreatitis. - Imaging features: Adenocarcinoma and focal pancreatitis are both hypoechoic at US, hypoattenuating at CT, and show the same signal intensity at T1- and T2-w images. Both can present with ductal strictures, double duct sign, infiltration of adjacent fat, arterial encasement, and peripancreatic venous obstruction. Imaging features in favor of a diagnosis of focal pancreatitis include: nondilated or smoothly tapering pancreatic and bile ducts coursing through the mass ("duct penetrating sign"), pancreatic duct irregularity, and the presence of pancreatic calcifications. Imaging features that favor a diagnosis of adenocarcinoma include: abrupt interruption of a smoothly dilated pancreatic duct and upstream pancreatic gland atrophy. A high ratio of duct caliber to pancreatic gland width is a recognized indicator of adenocarcinoma. Modest atrophy and nonabrupt gradual narrowing of the biliary or pancreatic duct is more common in focal pancreatitis. Page 23 of 50

Fig. 21: 64-year-old female with pseudotumoral chronic pancreatitis. Axial plain (a) and pancreatic phase (b) contrast-enhanced CT images reveal a solid hypodense and hypovascular mass in the head of pancreas, with some calcifications. (c) MRCP reveals mild dilatation of the CBD and MPD. However, the MPD is not interrupted and courses through the mass. There is also dilatation of small side branch ducts. References: J. Brito, Portimão/PT Page 24 of 50

Fig. 22 References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Paraduodenal pancreatitis - A form of focal pancreatitis. - Pancreaticoduodenal groove - potential space between the pancreatic head, duodenum, and CBD. - Two forms of paraduodenal pancreatitis : 1. 2. segmental form - extends to the pancreatic head with scar tissue in the pancreaticoduodenal groove, and can be misdiagnosed as pancreatic adenocarcinoma. pure form - affects exclusively the groove and spares the pancreatic head. - Two macroscopic types: 1. 2. Prevalent solid - micro-cysts (<1cm) Prevalent cystic - macro-cysts (>1cm) - Clinical manifestations generally relate to associated duodenal and biliary obstruction, with recurrent vomiting due to duodenal stenosis. - Imaging features: US - fibrous tissue in the pancreaticoduodenal groove appears as a hypoechoic lesion CT - hypoattenuating fibrotic scar tissue in the pancreaticoduodenal groove (with delayed enhancement); cystic thickening of the duodenal wall with or without duodenal stenosis; CBD dilatation MRI - sheet like fribrotic tissue in the pancreatic groove hypointense at T1-w MRI; hypo-, iso- or hyperintense at T2-w imaging. At contrast enhanced CT and MRI it shows delayed enhancement. Associated with smooth stricturing of the pancreatic portion of the CBD, and wall thickening and cystic dysplasia of the duodenum. Page 25 of 50

Fig. 23: 45-year-old man with paraduodenal pancreatitis. Plain (a), pancreatic (b) and late (c) phase axial CT images reveal pancreatic calcifications due to chronic pancreatitis. A hypovascular mass-like hypovascular lesion is observed in the head of pancreas, with indisctinct margins and late enhancement observed in the pancreaticoduodenal groove. Endoscopic US reveals thickening of the duodenal wall, with indefinition of the external layer regarding the pancreatic parenchyma. These findings suggested paraduodenal pancreatitis, a diagnosis that was improved by comparison with a previous CT (e), where cystic dystrophy of the duodenal wall was also observed. References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Page 26 of 50

Fig. 24 References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Lipoma - Lipomas are benign rare, small, homogenous and well-circumscribed pancreatic tumors consisting of mature adipose cells within a thin collagen capsule. - Imaging features: Well-defined, homogenous lesions without infiltration of peripancreatic fat tissue, widening of the MPD and the CBD. US - usually hyperechoic, although some lesions may demonstrate hypoechogenicity. CT - low homogenous density (from -120 HU to -30 HU) with no enhancement MRI - signal intensity identical to that of fat in all MRI pulse sequences, with signal drop out in the fat saturated images but not in out of phase image (chemical shift imaging). Thin fibrous septa of low signal intensity on T1- and T2-w images may traverse the lesion. Page 27 of 50

Fig. 25: Pancreatic lipoma in a 63-year-old woman. Axial (a), coronal (b) and sagital (c) contrast enhanced CT images in the portal venous phase show a homogeneous fat density nodule in the pancreatic isthmus. References: J. Brito, Portimão/PT Fig. 26 References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Page 28 of 50

Fat infiltration - Associated with a variety of diseases: obesity, diabetes mellitus, chronic pancreatitis, hereditary pancreatitis, obstruction of the pancreatic duct by calculus or tumor, and cystic fibrosis. - It may occassionally simulate a lesion, particularly where fatty replacement is uneven, typically between the ventral (uncinate process) and dorsal pancreas (areas usually spared from fatty infiltration). type 1a : preferential fatty replacement of head type 1b : preferential fatty replacement of head, neck and body type 2a : preferential fatty replacement of head and uncinate process type 2b : fatty replacement of most of pancreas except peribiliary region - Imaging features: Absence of mass effect, nondeformity of the pancreas and absence of ductal or vascular displacement in the affected area. US - focal fatty infiltration is hyperechoic relative to the normal pancreas, whereas focal fatty sparing is hypoechoic relative to the surrounding fatty pancreas. CT - low attenuation in areas of fatty infiltration, normal density in spared areas. MRI - the fatty regions will be isointense or even hyperintense relative to the surrounding parenchyma on in-phase gradient-echo T1-w images. Opposedphase gradient-echo images typically show a loss of signal intensity. Page 29 of 50

Fig. 27: Fatty replacement in a 72-year-old woman. US (a) reveals a hypoechoic image in the ventral pancreas. Plain CT (b) shows that the image corresponds to the uncinate process with a normal density, but hyperdense as compared to the fattyreplaced dorsal pancreas. References: J. Brito, Portimão/PT Page 30 of 50

Fig. 28 References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Pancreatic Lobulation - The pancreas has a normal lobulated appearance. - A prominent focal exophytic lobulation may simulate a pancreatic mass. - Lobulations are most frequently located in the pancreatic head and neck. - 34% of the population. - Lobulations are classified in three types: 1. 2. 3. type I (anterior [10% of cases]) type II (posterior [19%]) type III (horizontal [5%]). - Imaging features: Page 31 of 50

- Characteristics identical to those of the rest of the pancreas: US - isoechoic CT - isoattenuating MRI - isointense Contrast - isoenhancing Fig. 29: 56-year-old female with prominent pancreatic lobulation. Axial contrast enhanced CT (a) reveals a lobulation of the pancreatic contour, resembling a mass. However, multiplanar reformation (MPR) (b) based on the same acquisition clearly shows there is no mass, as the lobulation has similar enhancement to the pancreatic parenchyma. References: J. Brito, Portimão/PT Page 32 of 50

Fig. 30 References: Department of Radiology, Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE; Portugal Images for this section: Fig. 3: Pancreatic ductal adenocarcinoma in a 65-year-old female. Contrast enhanced axial (a) and coronal (b) CT images in pancreatic phase shows a hypovascular ill-defined Page 33 of 50

lesion in the pancreatic body. (c) Endoscopic US shows a heterogeneous hypoechoic tumor, with irregular borders. Fig. 4: Pancreatic ductal adenocarcinoma in a 58-year-old male. (a) In T2-w image the lesion appears hypointense. (b) Gadolinium enhanced MRI in pancreatic phase reveals a hypovascular mass. (c) MRCP image showing dilatation of the CBD (orange open arrow) and MPD (green open arrow) - the double duct sign. Page 34 of 50

Fig. 7: PNET in a 69-year-old woman. Axial non-enhanced CT shows a isoattenuating mass (orange arrow) in the head of the pancreas. (b) Axial postcontrast arterial phase CT image shows a tumor with heterogeneous arterial enhancement (orange arrow). (c) Axial postcontrast late phase CT image shows that the tumor (orange arrow) returns to be isoattenuating to the pancreas. (d) Reformatted curved CT showing dilatation of the MPD (open green arrow). (e) US reveals a hyopoechoic mass (orange arrow) in the head of the pancreas, with dilatation of the MPD (open green arrow). (f) Axial T1-w MRI shows a hypointense tumor (orange arrow) in the pancreatic head. (g) Axial T2-w image reveals a slightly hyperintense mass (orange arrow) in the head of pancreas. (h) Axial T2-w image fused with diffusion shows restriction to diffusion by the tumor (orange arrow). Page 36 of 50

Fig. 11: Focal large cell lymphoma of the pancreas, in a 54 years-old male. Axial (a) and coronal (b) contrast enhanced CT in portal venous phase shows a hypodense illdefined nodule (orange arrow) in the body of the pancreas. (c) Axial T1-w image shows a hypointense nodule (orange arrow) in the body of the pancreas. (d) In axial T2-w image the tumor is isointense to the pancreas. (e) T1-w image after gadolinium administration shows a hypovascular nodule (yellow arrow) in the pancreatic body. Posterior to the nodule, outside the pancreas but adjacent to it, there are two adenopathies (green open arrow). (f) PET scan shows FDG uptake by the lesion (orange arrow). Page 38 of 50

Fig. 12: Diffuse large cell lymphoma of the pancreas, in a 57 years-old male. Axial CT in arterial (a) and portal venous (b) phases shows diffuse enlargement of the entire pancreas with relatively homogeneous enhancement. (c) Coronal contrast enhanced CT image showing a stent in CBD. (d) US image shows a hypoechoic and enlarged pancreas. Page 39 of 50

Fig. 14: Acinar cell carcinoma in a 58-year-old man. (a) Axial non-enhanced CT shows a isoattenuating mass in the body of the pancreas. (b) Axial T1-w MRI shows a hypointense tumor (orange arrow) in the pancreatic body. (c) Axial T2-w image reveals a hyperintense mass in the body of pancreas (orange arrow). (d) MRCP sequence shows dilatation and tortuosity of the MPD (green open arrow) distal to the mass. (e, f, g) Axial T1-w image, non-enhanced (e), gadolinium enhanced in arterial (f) and delayed (g) phases showing mild heterogeneous enhancement of the lesion with a well defined enhancing capsule (orange arrow). (h) Axial T2-w image fused with diffusion shows restriction to diffusion by the tumour (orange arrow). Page 40 of 50

Fig. 29: 56-year-old female with prominent pancreatic lobulation. Axial contrast enhanced CT (a) reveals a lobulation of the pancreatic contour, resembling a mass. However, multiplanar reformation (MPR) (b) based on the same acquisition clearly shows there is no mass, as the lobulation has similar enhancement to the pancreatic parenchyma. Page 48 of 50

Conclusion In addition to pancreatic adenocarcinoma, a vast array of lesions and pseudolesions may present as a solid appearing pancreatic mass. Diagnosis can be quite challenging, and the use of a multimodality imaging approach is the best strategy in complex cases. Differential diagnosis is critical, in order to avoid inadequate treatment options. Personal information Ana Loureiro e-mail: analoureiro@claperm.com Hospital: Instituto Português de Oncologia de Lisboa, Francisco Gentil, EPE Department of Radiology Director: Dr. José Venâncio Helena Tavares Sousa e-mail: helenatsousa@gmail.com Hospital: Centro Hospitalar do Algarve, EPE Department of Gastroenterology Jorge Brito e-mail: jbmbrito@gmail.com Hospital: Centro Hospitalar do Algarve, EPE Deparment of Radiology References Page 49 of 50

1. 2. 3. 4. 5. 6. 7. Coakley FV, Hanley-Knutson K, Mongan J, Barajas R, Bucknor M, Qayyum A. Pancreatic imaging mimics: part 1, imaging mimics of pancreatic adenocarcinoma. AJR Am J Roentgenol. 2012 Aug;199(2):301-8. Raman SP, Hruban RH, Cameron JL, Wolfgang CL, Fishman EK. Pancreatic imaging mimics: part 2, pancreatic neuroendocrine tumors and their mimics. AJR Am J Roentgenol. 2012 Aug;199(2):309-18. Galvin A, Sutherland T, Little AF. Part 1: CT characterisation of pancreatic neoplasms: a pictorial essay. Insights Imaging. 2011 Aug;2(4):379-388. Epub 2011 May 18. Sutherland T, Galvin A, Little AF. Part 2: CT characterisation of pancreatic neoplasm: tumour mimics. Insights Imaging. 2011 Aug;2(4):389-397. Epub 2011 May 18. Low G, Panu A, Millo N, Leen E. Multimodality imaging of neoplastic and nonneoplastic solid lesions of the pancreas. Radiographics. 2011 JulAug;31(4):993-1015. Kim SY, Park SH, Hong N, Kim JH, Hong SM. Primary solid pancreatic tumors: recent imaging findings updates with pathology correlation. Abdom Imaging. 2013 Oct;38(5):1091-105. Ganeshan DM, Paulson E, Tamm EP, Taggart MW, Balachandran A, Bhosale P. Solid pseudo-papillary tumors of the pancreas: current update. Abdom Imaging. 2013 Dec;38(6):1373-82. Page 50 of 50