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72 Cards in this Set

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What is true of most pancreatic neoplasms?
Can appear as either cystic or solid masse
What are the categories of cystic pancreatic neoplasms?
1) Serous cystadenoma



2) Mucinous cystic tumor



3) Intraductal papillary tumors



4) Rare tumors
What is the most classic type of serous cystadenoma?
Microcystic variety (microcystic serous cystadenoma)
What is its basic appearance?
Microcysts defined and separated by dense fibrous septae
What is the maximum size of the cysts?
2 cm
What is a variation in its appearance?
Fibrous septae become so dense and the cysts so small that you cannot appreciate the cysts at all really. Lesion is always denser centrally. If you are going to see cysts, you will see them peripherally.
What is seen on the periphery of the lesion?
Larger cysts predominate peripherally, smaller cysts and more fibrous tissue centrally.
Is microcystic serous cystadenoma calcified?
20% of the time has CENTRAL calcification
What is the behaviour of microcystic serous cystadenoma?
BENIGN
How is microcystic serous cystadenoma treated?
If asymptomatic, it is left right where it is.
How common is microcystic serous cystadenoma?
It is rare
What is the appearance on MRI?
On T2WI, bright peripherally because of the cysts. Dense central fibrous stroma
What are the basic categories of unilocular macrocystic tumors?
Those arising in the parenchyma of the pancreas, and those arising from within a duct
If you have a peripheral (parenchymal) macrocystic tumor, what do you do next?
Evaluate its wall
What are the choices for wall?
Smooth and thin


OR



Nodular
What does smooth thin wall suggest?
The macrocystic tumor is likely mucinous.
What about their behavior?
usually BENIGN
What does nodular wall suggest?
still more likely mucinous than serous, but commonly MALIGNANT
What differentiates a thin walled unilocular cystic mass from pseudocyst?
May be difficult, but if there is a septation, that is commonly seen with mucinous neoplasm.
Where are the thin walled mucinous tumors located?
Tail or other part of proximal pancreas (head is considered distal pancreas)
Do thin walled mucinous tumors calcify?
Yes
What is the pattern of calcification?
Calcify peripherally, just the opposite of serous cystadenomas.
When you see a unilocular cystic mass in the proximal pancreas with thin wall and a single septation, what is your diagnosis?
Benign mucinous tumor, probably cystadenoma.
What is the treatment for benign mucinous cystic tumor?
Resection
When you do see a unilocular mass with one or more nodules in the wall, what is the most likely diagnosis?
MALIGNANCY, most commonly cystadenocarcinoma
Regarding the septum:
The septation seen in a benign tumor should just be very thin, barely perceptible. If it starts becoming thick, that is the same as a nodular wall, and you are likely dealing with a malignant neoplasm.
If you have an intraductal mass, where in the duct does it arise?
Can arise in EITHER the main pancreatic duct, or a branch duct.
When the tumor originates in the main pancreatic duct, what is the significance?
all are MALIGNANT invasive adenocarcinomas
What about branch duct originating tumors?
No clear cut behavior pattern
What is the sign of a main duct tumor?
Dilatation of portion or all of main pancreatic duct.
When you see dilatation of a duct and suspect tumor, what is the question you need to ask?
Does the patient have history of chronic pancreatitis?
Why is that important?
Absence of history of chronic pancreatitis, by history and imaging, strongly favors IPMT
What is IPMT?
Intraductal papillary mucinous tumor
How is diagnosis of IPMT confirmed?
ERCP
What is behaviour of IPMT?
As discussed before, all tumors of main pancreatic duct = MALIGNANT
What do these tumors do to the duct?
They infiltrate the duct, causing it to become markedly dilated and you can see nodularity of the tumor along the distended duct walls. The duct becomes distended with secretions as well as mucin produced by the tumor.
Where are branch duct intraductal papillary mucinous tumors found?
Most commonly in the uncinate process
What do they look like?
Unilocular masses
How are they best diagnosed?
They will usually fill on ERCP. However, sometimes the branch duct becomes obstructed by the mucinous tumor secretions, and thus may not be visualized on ERCP. Therefore, the best way to diagnose these lesions is now considered to be MRCP.
Are branch duct IPMTs malignant?
They can be.
What do they look like?
Hypodense mass within the uncinate process.
Are branch duct IPMTs really unilocular?
No. May have small or large locules. But these are not readily visualized on imaging. Of course with high resolution imaging they can be, however.
What is SPEN tumor?
Solid papillary epithelial neoplasm
Is SPEN more or less common than IPMTs?
Less. An unusual lesion.
When should you consider the diagnosis of SPEN tumor?
Hypodense complex cystic to partially solid appearing pancreatic mass in a YOUNG WOMAN
Are they malignant?
Locally aggressive, but do not metastasize
So, when do you think of SPEN?
Unilocular hypodense cystic or partially solid mass in the absence of pancreatitis in a WOMAN aged 18 - 30 (YOUNG).
What is done with SPENs?
RESECTED
So, what is the tumor that is universally considered benign?
Microcystic serous tumor
What tumors are considered variable with regards to malignancy?
Mucinous tumors
When you are dealing with a mucinous cystic mass (cystadenoma), is it more likely benign or malignant?
Most are benign (65%).


30% have potential to be locally invasive.


5% frankly malignant
So, what is the appearance of the ones that are pretty much always benign?
The appearance of mucinous cystadenoma that is almost univerally benign is the unilocular cystic mass with thin walls and a single thin septation.
What are the features that make a unilocular pancreatic mass more likely malignant?
1) Wall thick (thicker than 2mm), with or without nodules.



2) Peripheral calcifications
What about IPMTs?
All considered malignant (main duct) or premalignant (branch duct = uncinate), but premalignant ones often grow very slowly, and thus uncertain whether to resect or watch.
What are the signs of IPMT malignancy?
Solid mass


Main pancreatic duct dilated


Diffuse or multifocal involvement


Calcified intraluminal content
When these lesions do go frankly malignant, what do they become?
Invasive adenocarcinoma
Basically, then:
If you have a solid pancreatic mass, it is adenocarcinoma until proven otherwise, and out it comes.


But if you have a cystic pancreatic mass, there are many possibilities, and the lesion's characteristics need to be analyzed.
What are criteria for pancreatic cystic tumor that can be followed?
Lesion less than 2.5 cm



Lesion displays NO solid elements



There is no extension into the main pancreatic duct
If you need to, how do you evaluate whether a lesion extends into the main pancreatic duct or is involving other duct?
MRCP or ERCP
So, if a unilocular lesion is seen, what is the first question to ask?
Is it peripheral or related to duct
If it is deemed peripheral, what is it?
Serous or mucinous cystadenoma (assuming it has benign features; if it had thick walls, calcs, nodular walls, large size you would have to consider mucinous or cystic cystadenocarcinoma). Could also be SPEN if correct age/sex.
If it is deemed related to ducts (by CT or MRCP or ERCP) what is it?
Most likely IPMT, then you must determine whether it involves central duct or not.
If you do follow-up imaging and there is evidence of some growth, what is the next step?
Recommend excision, regardless of what the differential for the lesion is. These all have potential for malignancy, and if it is giving you a sign by getting bigger, take it out.
What is another way to evaluate whether the lesion involves ducts? (actually, the first way it should be attempted?)
Do multislice volume rendering of the area of interest. Basically gives you a 3-D slab that you can visualize more information on than single slice.
DDx for cystic pancreatic mass:
MOST CYSTIC PANCREATIC MASSES ARE NOT EVEN NEOPLASMS. MOST ARE PSEUDOCYSTS. THAT IS THE FIRST DIAGNOSIS YOU MUST EXCLUDE. DO SO BY GETTING A POSITIVE HISTORY OF RECENT PANCREATITIS. IF POSITIVE HX, MOST LIKELY PSEUDOCYST. CAN ALSO BE FOCAL PANCREATIC NECROSIS. AND CAN ALSO BE CYSTIC DYSTROPHY OF THE DUODENAL WALL, ALSO A SEQUELA OF PANCREATITIS.



Other possibilities: Choledochal cysts.

Duodenal diverticulum can masquerade as pancreatic mass! All you gots to do is a GI if you are worried about this.

Duplicaton cyst of the duodenum.


Rare tumors (adenosquamous)


Mets (melanoma)


Malignant GIST tumor of adjacent stomach
What are the types of choledochal cyst?
1 to 5
What is type 1?
Fusiform dilatation of the common duct
What is type 2?
Diverticulum off of the common duct
Type 3?
Choledochocele -- intraduodenal diverticulum off of the CBD
Type 4?
Dilated common duct and intrahepatic cysts
Type 5?
Caroli disease -- Multiple intrahepatic cysts
Most important points:
1) Classic microcystic serous cystadeno is benign



2) When you have unilocular mass, most common entities are NOT EVEN NEOPLASMS



3) When basic non-neoplastic entities ruled out, determine whether the lesion is peripheral or ductal.



4) If it is peripheral, consider patient age/sex. If young woman, SPEN. If not, evaluate wall thickness/nodularity and wall calcification. If present, resect. If not, look at overall size. If small (2.5 cm or less) watch it. If it grows in 3-6 months, resect.



5) If ductal, evaluate whether main duct involved or just branch duct. If main duct involved, resect. If just branch duct (most common location uncinate process), evaluate size of lesion. If under 2.5 cm, consider follow up in 3-6 months. If growth, resect.