Pancreas (for PBR 2)

Question 1

Two morphologic types of pancreatitis

Answer 1

Interstitial edematous

Acute necrotizing pancreatitis

Question 2

Imaging finding of interstitial edematous pancreatitis

Answer 2

CE CT:

Localized or diffuse enlargement of the pancreas with normal homogeneous parenchymal

Slightly heterogeneous enhancement due to edema

Mild fat stranding and peripancreatic inflammatory changes may be present with varying fluid volumes of peripancreatic fluid

Question 3

Acute necrotizing pancreatitis is divided into three forms by CT appearance

Answer 3

1. Pancreatic parenchymal necrosis with peripancreatic necrosis
2. Peripancreatic necrosis alone
3. Pancreatic parenchymal necrosis alone

Question 4

Most common form of acute necrotizing pancreatitis

Answer 4

Pancreatic parenchymal necrosis with peripancreatic necrosis

Question 5

Imaging finding of pancreatic parenchymal necrosis with peripancreatic necrosis

Answer 5

Lack of parenchymal enhancement associated with nonliquefied heterogeneous areas of nonenhancement in peripancreatic tissues, most commonly in the lesser sac and retroperitoneum

Question 6

Pancreatic necrosis is best determined by CT at approximately how many hours following onset of symptoms?

Answer 6

72 hours

Question 7

Collections associated with interstitial pancreatitis

Initial 4 weeks as nonencapsulated, nonenhancing, low attenuation, liquid collections without solid components

Walls are imperceptible

Answer 7

Acute peripancreatic fluid collections

Question 8

These are defined as simple collections with perceptible walls seen after 4 weeks

Answer 8

Pseudocyst

Question 9

Collections associated with necrotizing pancreatitis seen in the first 4 weeks

Answer 9

Acute necrotizing collections

Heterogeneous collections containing hemorrhage, fat, or necrotic fat within or surrounding necrotic pancreatic parenchyma

Question 10

An enhancing wall may develop around an acute necrotic collection and seen after 4 weeks -

What is the term of the collection?

Answer 10

Walled-off necrosis

WONs appear heterogeneous in attenuation and complex because of variable necrotic tissues and debris

Question 11

This is caused by recurrent and prolonged bouts of acute pancreatitis that cause parenchymal atrophy and progressive fibrosis

Answer 11

Chronic pancreatitis

Both exocrine and endocrine function of the pancreas may be impaired

Question 12

Most common cause of chronic pancreatitis

Answer 12

Alcohol abuse (70%)

Biliary stone disease (20%)

Question 13

Morphologic changes and imaging findings of chronic pancreatitis

Answer 13

1. Dilation of the pancreatic duct (usually in a beaded pattern of alternating areas of dilation and constriction)
2. Decrease in visible pancreatic tissue because of atrophy
3. Calcifications (finely stippled to coarse)
4. Focal-mass-like enlargement of the pancreas (owing to benign inflammation and fibrosis)
5. Stricture of the bile duct (because of fibrosis or mass in the pancreatic head resulting in proximal bile duct dilation)
6. Fascial thickening and chronic inflammatory changes in surrounding tissues

Question 14

Also known as lymphoplasmacytic sclerosing pancreatitis

Unique form of pancreatitis caused by autoimmune disease associated with elevation of IgG4

Answer 14

Autoimmune pancreatitis

Question 15

Extrapancreatic manifestations of autoimmune pancreatitis

Answer 15

Inflammatory bowel disease (ulcerative colitis)
Long segment bile duct strictures
Lung nodules
Lymphadenopathy
Lymphocytic infiltrates in the liver and kidneys
Retroperitoneal fibrosis
Sjogren syndrome

Question 16

Findings that favor diagnosis of autoimmune pancreatitis over adenocarcinoma

Answer 16

1. Diffuse or focal swelling of the pancreas with characteristic halo of edema
2. Extensive peripancreatic stranding and edema are absent
3. Diffuse or segmental narrowing of the pancreatic duct and/or the common bile duct
4. Absence of dilation of the pancreatic duct and absence of parenchymal atrophy proximal to the pancreatic mass (theses findings are typically present with adenocarcinima)
5. Fluid collections and parenchymal calcifications are typically absent
6. Peripancreatic blood vessels are usually not involved
7. Kidneys are involved in 1/3 of cases (round-wedge-like , or diffuse peripheral patchy areas of decreased contrast enhancement)

Question 17

This is an uncommon form of pancreatitis that may also mimic adenocarcinoma

Fibrosis in the groove between the head of the pancreas, the descending duodenum, and the common bile duct produces an inflammatory mass that obstructs the common bile duct

Answer 17

Groove pancreatitis

Question 18

Characteristic finding of groove pancreatitis

Answer 18

1. Sheet-like mass in the pancreaticoduodenal groove
2. Atrophy and fibrotic changes in the pancreatic head
3. Small cysts along the wall of the duodenum
4. Duodenal wall thickening and luminal narrowing
5. Tapering stenosis of the common bile and pancreatic ducts
6. Widening of the space between the distal ducts and the wall of the duodenum (rarely seen with adenocarcinoma)
7. Enhancement is delayed but progressive

Question 19

Signs of resectability of pancreatic adenocarcinoma

Answer 19

1. Isolated pancreatic mass with or without dilation of the bile or pancreatic ducts
2. No extrapancreatic disease
3. No encasement of celiac axis or SMA

Question 20

Signs of potential resectability

Answer 20

1. Absence of involvement of the celiac axis or SMA
2. Occlusion of the superior mesenteric or portal vein without a technical option for reconstruction
3. Liver, peritoneal, lung, or any other distant metastases

Question 21

Evidence of arterial encasement that indicates unresectability

Answer 21

1. Tumor abutting >180 degrees of the circumference of the artery
2. Tumor abutment focally narrowing the artery
3. Occlusion of the artery by tumor

Question 22

These tumors may be functioning producing hormones resulting in distinct clinical syndromes, or may be nonfunctional and grow to large size before presenting clinically

Answer 22

Neuroendocrine (islet cell) tumors

Question 23

Different types of neuroendocrine (islet cell) tumors

Answer 23

Insulinomas
Gastrinomas
Glucagonoma
Somatostatinoma
VIPoma

Question 24

80% of nonfunctioning tumors are:

a. benign
b. malignant

Answer 24

Malignant

Question 25

Imaging findings of nonfunctioning neuroendocrine tumors

Answer 25

``` Coarse calcifications Cystic degeneration Necrosis Local and vascular invasion Metastases ```

Question 26

CT scan finding of lymphoma

Answer 26

Homogeneous, of lower attenuation than muscle, and show limited enhancement Lesions can be localized, well-defined mass, or be infiltrating diffusely enlarging or replacing gland Attenuation may be so lows as to appear cystic

Question 27

Types of fatty lesions of the pancreas

Answer 27

Diffuse fatty infiltration (associated with aging and obesity and is seen with pancreatic atrophy) Focal fatty infiltration (between the lobules of pancreatic parenchyma) Focal fatty sparing (in diffuse infiltration may simulate a pancreatic mass, especially when it involves the head or uncinate process Lipoma

Question 28

Most common pancreatic cystic lesions

Answer 28

Pancreatitis-associated fluid collections

Question 29

Findings of pancreatitis-associated fluid collections

Answer 29

1. Fluid-density unilocular cyst (associated with findings of acute or chronic pancreatitis) 2. Complex cystic mass (with internal hemorrhage, infection, or gas) 3. Most are round or oval with a thin or thick wall that may enhance (however, cyst contents do not enhance) 4. Septations and lobulated contours (unusual and more often associated with serous cystadenoma) 5. Some lesions may be infected showing the presence of gas and debris within the lesion 6. Serial imaging usually shows involution of noninfected collections

Question 30

What are the three major appearances of serous cystadenomas

Answer 30

1. Honeycomb microcyst (microcystic adenoma) with innumerable cysts 1 mm to 2 cm size - MOST COMMON 2. Macroscropic form with larger cysts 3. Innumberable tiny cysts Lesions do not communicate with the pancreatic duct

Question 31

Classification of cystic mucinous neoplasms of the pancreas

Answer 31

Papillary mucinous neoplasm | Mucinous cystic neoplasm

Question 32

In cystic mucinous neoplasms: "Worrisome features"

Answer 32

1. Cysts >3 cm diameter 2. Enhancing thickened cyst walls 3. Main pancreatic duct diameter 5 to 9 mm 4. Mural nodules without enhancement 5. Abrupt narrowing of main pancreatic duct w/ proximal atrophy of pancreatic parenchyma 6. Regional lymphadenopathy

Question 33

In cystic mucinous neoplasms: "High-risk stigmata"

Answer 33

1. CBD obstruction w/ jaundice associated w/ cystic tumor in pancreatic head 2. Enhancement of solid components 3. Main pancreatic duct >10 mm

Question 34

Intraductal papillary mucinous neoplasms are classified into 3 morphologic types

Answer 34

``` Branch duct (BD-IPMN) Main duct (MD-IPMN) Mixed type ```

Question 35

Type of IPMN : Most common in the uncinate process arising in branches of the main pancreatic duct to form grape-like collections of small cysts (5- to 20-mm diameter) that communicate with the ductal system

Answer 35

Branch duct - IPMN Some lesions consist of a single unilocular cyst Cyst have thin walls w/ flat or papillary lining that produces tenacious mucin Invasive carcinoma - 17%

Question 36

Type of IPMN : This is characterized by diffuse or segmental dilation of the main pancreatic duct >5-mm diameter without evidence of other causes of obstruction

Answer 36

Main duct - IPMN Diffusely or partially dilated, tortuous and irregular, main pancreatic duct is filled with mucin produced by tumor cells

Question 37

Presence of ovarian stroma in addition to mucin-producing epithelial tumor cells is specific to this pancreatic tumor Occurs nearly always in women Do not arise from or communicate with the pancreatic duct

Answer 37

Mucinous cystic neoplasm

Question 38

Imaging finding of mucinous cystic neoplasm

Answer 38

1. Cystic lesion larger than 2 cm nearly always in the pancreatic tail 2. Tumors are multilocular with a few compartments or uncommonly unilocular 3. Papillary projections of solid tumor are common 4. Peripheral eggshell calcification - uncommon but highly specific finding

Question 39

This is a rare low-grade pancreatic malignancy that presents as a large encapsulated mass with a mixture of fluid, hemorrhagic, necrotic, and solid components It is not truly papillary or cystic

Answer 39

Solid pseudopapillary tumor Pseudopapillae are formed by layers of epithelial cells that cover a fibrovascular core

Question 40

Imaging finding of a solid pseudopapillary tumor

Answer 40

CT shows a heterogeneous well-encapsulated tumor with variable cystic and solid components Solid areas, usually in the periphery, enhance Peripheral calcifications may be present

Question 41

Cystic change in neuroendocrine tumors are a result of what process?

Answer 41

Tumor degeneration

Question 42

Cystic change in adenocarcinoma is the result of what process?

Answer 42

Necrosis, hemorrhage, or formation of pseudocysts adjacent to the neoplasm