Cystic lesions of pancreas : about the most common cystic lesions of pancreas and its imaging approach to narrow down the diagnosis.

1. APPROACH TO ACCIDENTAL
DETECTION OF PANCREATIC
CYSTIC LESIONS
Dr. Rajesh Rimal

4. How common ??
• 1.2 % to 20 %
• Very small risk that an incidental pancreatic cyst may be malignant.
• Most commonly encountered pancreatic cysts include intraductal
papillary mucinous neoplasms ( IPMNs) , serous cystadenoma ,
mucinous cystic neoplasm ( MCN ) , and pseudocysts.

5. • Risk of malignant transformation in pancreatic cysts is estimated to
be 0.24 % per year, depending on histological subtype.

6. REPORTING CONSIDERATIONS
• Cyst morphology, location
• Cyst size
• Possible communication with Main Pancreatic Duct
• Presence of ” worrisome features “ and/or “ high-risk stigmata “
• Growth on follow-up examination
• Multiplicity

7. ACR Recommendations
• Recording a single measurement of the greatest length of the cyst in
the long axis on either axial or coronal image , and and also reporting
the corresponding image and series numbers.
• Radiologists to use the specific terms “ worrisome features “ or “ high
risk stigmata “ in their reports , when applicable .
• A simple 7-mm duct threshold be used.

8. • Radiologists report whether growth has occurred on follow up
examinations according to the following :
• For cysts < 0.5 cm ,growth is represented by a 100% increase in long-axis
diameter.
• For cysts 0.5 cm and < 1.5 cm , a 50 % increase in long-axis diameter :
• For cysts > 1.5 cm , a 20 % increase in long-axis diameter.

9. • When possible, radiologists should also report a cyst’s growth rate (
mm/yr ).
• Any cyst undergo EUS and FNA before resection , to minimize
unnecessary surgery.
• For FOLLOW up CT=MRI
• Regardless of the modality , intravenous contrast , multiphase
acquisitions, and thin sections for 3D visualization are generally
needed.

10. • Pancreatic-phase images should begin about 50 seconds after
initiating the intravenous contrast injection . Injection rates of 4-5
ml/s may optimally display peripancreatic vasculature and maximize
pancreatic enhancement . A second phase is recommended at
approximately 80 seconds.

11. Worrisome Features and High risk stigmata
• Worrisome Features
• Cyst >= 3 cm
• Thickened / enhancing cyst wall
• Nonenhancing mural nodule
• Main pancreatic duct caliber >= 7 mm

12. High-risk Stigmata
• Obstructive jaundice with cyst in head of pancreas
• Enhancing solid component within cyst
• Main pancreatic duct caliber >= 10 mm in absence of obstruction

13. • Cysts lacking these features are stratified based on size .
• But the risk of malignant transformation in cysts < 3 cm in size is
extremely low , the risks of performing EUS-FNA in this setting may
outweighs the diagnostic benefits.

14. ACR APPROPRIATENESS CRITERIA

20. Management of Incidental Pancreatic Cysts
• INCLUSION / EXCLUSION CRITERIA FOR USE OF THE ALGORITHM
• These should be applied to incidentally detected pancreatic cysts only if the
patient is both an adult ( 18 years of age ) and asymptomatic.
• We advise the default assumption that all are mucinous ( eg, small IPMN )
and require observation , knowing that the majority will be indolent.

21. • A cyst size of 1.7 cm contains sufficient fluid to perform FNA with
cytology and carcinoembryonic antigen and amylase levels.
• A cyst size of 3 cm alone is considered a worrisome features
associated with a 3-times greater risk of cyst-related malignancy.
• EUS-FNA should be considered for any cyst 2.5 cm with at least one
worrisome feature

27. • Small lesions vs large lesions
• Small lesions – characterization is often not possible.
• Large lesions – need to be differentiated between premalignant and
malignant .

28. Classification
• Pseudocysts
• Common cystic neoplasms:
• IPMN – Intraductal papillary mucinous neoplasm
• Serous cystic neoplasm ( SCN )
• Mucinous cystic neoplasm ( MCN )
• Uncommon cystic neoplasms:
• Solid pseudopapillary epithelial neoplasm ( SPEN )
• Tumors with cystic degeneration : adenocarcinoma – neuroendocrine tumor

30. Systemic Approach
Detection of cystic pancreatic lesion
Differentiate between non-malignant vs malignant lesion

31. • Imaging characteristics of cyst
• History
• Cyst fluid analysis

34. Pseudocyst
• History of pancreatitis or abdominal trauma.
• Develop in 4-6 weeks – usually decrease in size over time –sometimes
enlarge or become infected.
• Unilocular cyst without solid components , central scar or wall
calcification.
• Collection of pancreatic enzymes , blood and necrotic tissue
• Debris within a cystic lesion is a specific MR finding.
• Found in any part of pancreas or anywhere within the abdomen and
sometimes even in the chest.

35. • Pseudocysts , unlike cystic pancreatic neoplasms , usually evolve in
size quickly , which may aid in distinction.

37. CYSTIC NEOPLASMS

38. MORPHOLOGICAL CHARACTERISTICS OF A
CYSTIC NEOPLASM
• Thick irregular rim
• Septations
• Solid components
• Dilated pancreatic duct > 3mm and calcifications.
• Fluid aspirated from a neoplastic cyst will show low amylase level

39. DIFFERENTIAL DIAGNOSIS

41. MUCINOUS CYSTADENOMA

43. • Premalignant tumor – may transform into a mucinous
cystadenocarcinoma.
• Exclusively seen in women – Typically in ’ Mother ‘ – median age : 40-
50 years.
• Most common clinical presentation : Nondescript abdominal pain.
• Location : Tail and body of the pancreas ( 95 % )

44. Imaging features
• Macrocystic ( >2 cm )
• Thick wall septations ( enhancing )
• Ovarian stroma
• Peripheral calcifications – Specific diagnosis
• No connection to the pancreatic duct.

47. Features suggestive of malignant
transformation
• Invasion of adjacent structures
• Nodal and distant metastases
• Larger lesion size ( cyst >= 4 cm )
• Thick irregular walls
• Enhancing soft-tissue components or mural nodules
• Peripheral calcifications
• Pancreatic duct dilatation

48. SEROUS CYSTIC NEOPLASM

50. • Benign tumor
• Typically seen in elderly female
• Sporadic but can be associated with Von hippel lindau disease.

51. IMAGING FEATURES
• Microcystic , macrocystic , mixed microcystic and macrocystic and
solid
• Microcystic or honey-combed cyst with central scar and calcifications.
• Lobulated surface
• No communication between cysts and pancreatic duct.

54. INTRADUCTAL PAPILLARY MUCINOUS
NEOPLASM

56. • Mucin producing tumor in main pancreatic duct or branch-duct.
• Must have communication with pancreatic duct
• Can be multifocal.
• Location : Pancreatic head >> tail and corpus.
• Histologically , it is classified as intestinal , pancreaticobiliary ,
gastric, and oncocytic subtypes
• Two types : Main duct and Branch duct.

57. Branch-duct IPMN
• 41-64 % of IPMNs.
• Uncinate process of pancreas
• Cluster of small cysts with lobulated margins and septa ( grapelike
lobulated appearance )

58. Main-duct IPMN
• 15 – 21 % of IPMNs
• Segmental or diffuse dilatation of the MPD caused by the tumor
mucin production.

59. Signs of malignancy are :
• Pancreatic duct > 8 mm
• Solid node in duct
• Mass around pancreatic duct
• Enlarged choledochal duct.
• Field defect ( synchronous vs metachronous)

60. SOLID PSEUDOPAPILLARY NEOPLASM

62. • Very uncommon neoplasm in women 20-30 years ( daughter ).
• Low grade malignant neoplasms
• Solid and cystic neoplasm with capsule and with early ‘hemangioma –
like ‘ enhancement .
• Intratumorl hemorrhage can be seen.

63. • Complex cystic componenets .
• Macrocystic ( 2.5-17 cm )
• Well-defined
• Internal hemorrhage

65. Imaging Features suggestive of malignant
transformation
• Size larger than 5-6 cm
• Location in the tail of pancreas
• Focal discontinuity of the capsule
• Liver lesions suggestive of metastases.

66. Take Home Message
• Worrisome features and high risk stigmata
• Surgical resection vs follow-up
• Different cystic lesions of pancreas
• Imaging features to suggestive malignant transformation

67. References
• .ACR Appropriateness Criteria Pancrreatic Cyst ( 2020 )
• Pancreatic Cystic Lesions and Malignancy : Assessment,Guidelines ,
and the Field Defect , Radiographics ( 2021 )
• Management of Incidental Pancreatic Cysts : A White Paper of the
ACR Incidental Findings Committee
• Pancreatic cystic lesions , Diagnosis and Management , Radiology
Assistant ( 2020 )

68. • THANK YOU