Pancreas and Spleen Flashcards
administration of this substance increases pancreatic secretions and improves visualization of the pancreatic duct during MRCP
secretin
tongue-shaped organ approximately 12 to 15 cm in length that lies within the anterior pararenal compartment of the retroperitoneum
pancreas
pancreas is posterior to the
left lobe of liver, stomach and lesser sac
head of the pancreas wraps around what vessel
junction of SMV and splenic vein
uncinate process of the pancreatic head extends under what vessel
SMV
vessel that courses through the pancreatic bed in an often tortuous course
splenic artery
maximum dimenstion of pancreas are
3.0 cm for the head, 2.5 cm for body and 2.0 cm for the tail
normal size of pancreatic duct
3 to 4 mm in the head and tapers smoothly to the tail
what part of the duodenum cradles the pancreatic head
C-loop
appearance of pancreatic tumors in MRI
lower signal than parenchyma on T1, on cystic lesions are bright on T2
normal retroperitoneal fat infiltrates pancreatic lobule in older patients because
it lacks capsule
most comprehensive initial imaging study for acute pancreatitis
contrast-enhanced MDCT
2 morphologic types of acute pancreatitis
interstitial edematous pancreatitis and acute necrotizing pancreatitis
appears as localized or diffuse enlargement of the pancreas with normal homogeneous parenchymal enhancement or slightly heterogeneous enhancement due to edema. mild fat stranding and peripancreatic inflammatory changes may be present with cvarying volumes of peripancreatic fluid
interstitial edematous pancreatitis
most common cause of chronic pancreatitis
alcohol abuse
most common cause of acute pancreatitis
gallstone passage/impaction
type of hyperlipidemia that is susceptible to pancreatitis
Type 1 and 5
infections that are susceptible to pancreatitis
mumps, hepatitis, infectious mononucleosis, AIDS, ascariasi, clonorchis
structural disorders that may be susceptible to pancreatitis
choledochocele, pancreas divisum
most common form of acute necrotizing pancreatitis
pancreatic parenchymal necrosis with peripancreatic necrosis
appearing as a lack of pancreatic parenchymal enhancement associated with nonliquefied heterogeneous areas of nonenhancement in peripancreatic tissues, most commonly in the lesser sac and retroperitoneum
pancreatic parenchymal necrosis with peripancreatic necrosis
pancreatic necrosis is best determined by what modality at 72 hours following onset of symptoms
CT
pancreatic pseudocyts are defined as simple collections with perceptible walls seen in how many weeks
after 4 weeks
true or false: pancreatic pseudocysts usually do not require drainage
true
Drainage is often required for pancreatic pseudocysts if there is
infected fluid collection
an enhancing wall may develop around an acute pancreatic necrotic collections and if seen after 4 weeks the collection is termed
“walled-off” necrosis
thin-walled peripancreatic collection peristing after 4 weeks without necrosis
pseudocyts
secondary infection in pancreatitis usually occurs at what week
2-3 weeks
this complication of pancreatitis is caused by autodigestion of arterial walls by pancreatic enzymes results in pulsatile mass that is lined by fibrous tissue and maintains communication with parent artery
pseudoaneurysm
this complication of pancreatitis is due to pancreatic necrosis resulting in a viable segment of the pancreas (most common in the neck) being disconnected from the intestinal tract and a persistent fistual with continuing leakage of fluid into peripancreatic spaces
disconnection of the pancreatic duct
common congenital variant pancreatic anatomy that serves as a predisposition to pancreatitis in which the ventral and dorsal ductal systems of the pancreas fail to fuse
pancreas divisum
In pancreatic divisum, the major portion of the pancreatic secretions from the body and tail via the
dorsal pancreatic duct (Santorini) into the minor papilla while the minor portion of pancreatic secretions from the head and uncinate process (ventral duct of Wirsung)
recurrent and prolonged bouts of acute pancreatitis that cause parenchymal atrophy and progressive fibrosis. Both the exocrine and endocrine function of the pancreas may be impaired
chronic pancreatitis
morphologic changes of chronic pancreatitis include
dilation of the pancreatic duct, usually in a beaded pattern or alternating areas of dilation and constriction, decrease in visible pancreatic tissue because of atrophy, calcifications in pancreatic parenchyma that vary from finely stippled to coarse, usually associated with alcoholic pancreatitis, fluid collections that are both intra- or extrapancreatic, focal mass-like enlargement of the pancreas owing to benign inflammation and fibrosis, stricture of the bile duct because of fibrosis or mass in the pancreatic head, fascial thickening and chronic inflammatory chanegs in surrounding tissues
unique form of pancreatitis caused by autoimmune disease associated with elevation of IgG4. this is common in men aged 40 to 65. presentation is often obstructive jaundice with history of recurrent mild abdominal pains
autoimmune pancreatitis
extrapancreatic manifestations of autoimmune pancreatitis occur in 30 % of patients and include
IBD, especially UC, long-segment bile duct strictures, lung nodules, lymphadenopathy, lymphocytic infiltrates in the liver and kidneys, retroperitoneal fibrosis and Sjogren syndrome
in this type of pancreatitis, there is periductal infiltration by lymphocytes and plasma cells with accompanying dense fibrosis results in diffuse enlargement of the pancreas and masses closely simulating adenocarcinoma
autoimmune pancreatitis
treatment for autoimmune pancreatitis
steroids
differentiation of autoimmune pancreatitis from adenocarcinoma include
diffuse or focal swelling of the pancreas with characteristic tight halo of edema, extensive peripancreatic stranding and edema are absent, diffuse or segmental narrowing of the pancreatic duct and/or common bile duct, absence of dilation of the pancreatic dut and absence of parenchymal atrophy proximal to the pancreatic mass, fluid collections and parenchymal calcifications are typically absent, peripancreatic blood vessels are usually not involved, kidneys are involved in one-third of cases showing round wedge-like, or diffuse peripheral patchy areas of decreased contrast enhancement
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. this is most common in middle-aged men with a long history of alcohol abuse
Groove pancreatitis
a highly lethal pancreatic tumor that usually unresectable at presentation. this is second only to colorectal cancer as the most common digestive tract malignancy
pancreatic adenocarcinoma
this pancreatic malignancy appears as a hypodense mass distorting the contour of the gland, associated findings include obstruction of the CBD and pancreatic duct and atrophy of pancreatic tissue proximal to the tumor
adenocarcinoma
metastases from pancreatic adenocarcinoma would go to
regional node, liver and peritoneal cavity
signs of resectability of pancreatic adenocarcinoma include
isolated mass with or without dilation of the bile or pancreatic ducts, no extrapancreatic disease, encasement of celiac axis or SMA, regional nodes may be involved and limited peripancreatic extension of tumor may be present
evidence of arterial encasement that indicates unresectability of pancreatic adenocarcinoma
tumor abutting >180 degrees of the circumference of the artery, tumor abutment focally narrowing the artery and occlusion of the artery by tumor
characteristic pancreatic duct dilatation of chronic pancreatitis
beaded dilatation
characteristic pancreatic duct dilatation in carcinoma
smooth ductal dilation
are calcifications common in pancreatic adenocarcinoma?
no
pancreatic tumors that may be functioning producing hormones resulting in distinct clinical syndromes, or may be nonfunctional and grow to large size before presenting clinically
neuroendocrine (islet cell) tumors
neuroendocrine pancreatic tumor that present with episodic hypoglycemia
insulinomas
neuroendocrine pancreatic tumor that present with peptic ulcers, diarrhea caused by gastric hypersecretion, or Zollinger-Ellison syndrome
gastrinomas
neuroendocrine pancreatic tumor that present as DM and painful glossitis
glucagonoma
neuroendocrine pancreatic tumor that preent with DM and steatorrhea
somatostatinoma
neuroendocrine pancreatic tumor that present with massive watery diarrhea
VIPoma
functioning neuroendocrine pancreatic tumor vary in malignant potential from __ for insulinoma, ___ for gastrinoma, ___ for glucagonoma
10% of insulinoma, 60% for gastrinoma, 80% for glucagonoma
functioning neuroendocrine tumors are usually less than what size
3 cm
how many percent of nonfunctioning neuroendocrine pancreatic tumor are malignant
80%
neuroendocrine pancreatic tumors that are nonfunctioning tend to be of what size
much larger (6-20 cm in diameter
metastatses to the pancreas are most frequent with what primary neoplasms
RCC and bronchogenic carcinoma
metastases to the pancreas may appear as
solitary, well-defined, heterogeneously enhancing mass as diffuse heterogeneous enlargement of pancreas or as multiple nodules
metastases from this primary malignancy appears hyperintense on T1
melanoma because of paramagnetic properties of melanin
associated finding in pancreatic lymphoma
enlarged peripancreatic lymph nodes
diffuse infiltration of the pancreas is associated with
aging and obesity, pancreatic atrophy
refers to unusual occurrence of macrocysts of varying size distributed throughout the pancreas in patients with cystic fibrosis
pancreatic cystosis
most common pancreatic cystic lesions representing up to 85% to 90% of cystic lesions. most are unilocular fluid collections confined by a fibrous wall that does not contain epithelium
pancreatitis-associated fluid collections
cyst fluid aspiration of pancreatitis-associated fluid collections reveal elevated
amylase levels
these are benign tumors not requiring treatment that most commonly occurs in women and distributed uniformly throughout the head, body and tail of pancreas. they appear as honeycomb microcysts (microcystic adenoma) with innumerable small cysts 1 mm to 2 cm in size, a macrocystic form with larger cysts is seen in 10% overlapping the appearance of mucinous cystadenoma
serous cystadenomas
highly diagnostic feature of serous cystadenoma of pancreas
central stellate scar that may calcify
diagnosis of serous cystadenoma of pancreas is confirmed if the aspirated cystic fluid shows
clear fluid without mucin and without tumor markers seen with cystic mucinous neoplasms of the pancreas such as CEA or carbohydrate antigen (CA 19-9, CA 72-4, CEACAM6)
classification of cystic mucinous neoplasms of pancreas
intraductal papillary mucinous neoplasms and mucinous cystic neoplasms
characterized pathologically by mucin-producing epithelial tumor cells that tend to form papillae and grow as cystic lesions
cystic mucinous neoplasms
recommended imaging for cystic mucinous neoplasms of pancreas larger or equal to 10 mm and cysts producing symptoms to check for “high-risk stigmata” or “worrisome features”
contrast-enhanced MDCT or MR with MRCP
worrisome features of cystic mucinous neoplasms include
cysts > or = o 3 cm diameter, enhancing thickened cyst walls, main pancreatic duct diameter of 5 to 9 mm, mural nodules without enhancement, abrupt narrowing of main pancreatic duct with proximal atrophy of pancreatic parenchyma and regional lymphadenopathy
“high-risk” stigmata of cystic mucinous neoplasms include
CBD obstruction with jaundice associated with cystic tumor in the pancreatic head, enhancement of solid components and main pancreatic duct diameter of > or = 10 mm
intraductal papillar mucinous neoplasms are divided into 3 morphologic types
branch duct, main duct, mixed type
type of IPMN that is characterized by diffuse or segmental dilatation of main pancreatic duct >5 mm in diameter without evidence of other causes of obstruction
main duct IPMN
most common type of IPMN
mixed type
rare type of pancreatic neoplasm that is low-grade, presents as a large (mean 9 cm) encapsulated mass with a mixture of fluid, hemorrhagic, necrotic and solid components. it is not truly papillary or cystic
solid pseudopapillary tumor
tumor that is often asymptomatic even though the lesions may exceed 20 cm in size. it closely resembles neuroendocrine tumors. it is heterogeneous, well-encapsulated tumor with variable cystic and solid components. solid areas in the periphery, enhance, peripheral calcifications may be present
solid pseudopapillary tumor
cystic change in pancreatic adenocarcinoma are usually from
necrosis, hemorrhage, or formation of pseudocysts
unilocular pancreatic cysts that are smaller than 10 mm are usually benign or malignant?
benign pseudocysts or retention cysts
largest lymphoid organ
spleen
true or false: there is no hematopoietic activity in the spleen
true
this organ sequesters abnormal and aged RBC and WBC and platelets and serves as a reservior for RBC
spleen
spleen size varies with
age, nutrition and hydration
spleen is relatively large at what age group
children
spleen size matures by what age
15
average spleen dimensions in adults
12 cm in length, 7 cm width, 3 to 4 cm in thickness
splenic artery occlusion instantly produces infarction of the spleen because
splenic arteries are end arteries without anastomosis or collateral supply
during arterial phase contrast enhancement of spleen, the parenchyma appears as alternating bands of high and low density, which is called
arciform pattern
resistance pattern of splenic vessels
low resistance fast-flow circulation with high-resistance slow flow filtering circulation
these are round masses, 1 to 3 cm in size and of the same imaging features as normal splenic parenchyma.they may be single or multiple and are usually located near the splenic hilum
accessory spleens
used to confirm suspected accessory spleens as functioning splenic tissue
technetium sulfur colloid radionuclide scans
term applied to normal spleen positioned outside of its normal location in the LUQ. may present as a palpable abdominal mass, atho most cause no symptoms
wandering spleen
pathophysiology of wandering spleen
laxity of splenic ligaments, commonly found in association with abnormalities of intestinal rotation
diagnosis of wandering spleen is made by
identifying the blood supply from splenic vessels and radionuclide scans
refers to multiple implants of ectopic splenic tissue that may occur after traumatic splenic rupture
splenosis
clinical sign of splenic regeneration
absence or disappearance Howell-Jolly bodies from PBS
rare congenital anomaly that features multiple small spleens, usually located in the right abdomen and associated with situs ambiguous. Both lungs are two-lobes. Most patients also have cardiovascular anomalies
Polysplenia
congenital absence of spleen, found in association with bilateral right-sidedness, midline liver and bilateral three-lobed lungs. most patients die before age 1
asplenia
50% of cases of splenomegaly are from
portal hypertension
30% of cases of splenomegaly are from
lymphoma
splenomegaly has a splenic size of
more than 14 cm
other helpful findings to diagnose splenomegaly
projection of spleen ventral to the anterior axillary line, inferior spleen tip extending more caudally than the inferior liver tip, inferior spleen tip extending below the lower pole of left kidney
most common malignant tumor involving the spleen either as primary or as part of systemic disease
lymphoma
patterns of splenic lymphoma include
diffuse splenomegaly, multiple masses of varying size, miliary nodules resembling microabscesses, large solitary mass, and direct invasion from adjacent lymphomatous nodes
common predisposing condition for splenic infarction
lymphoma
most common tumors to metastasize to the spleen are
malignant melanoma, lung, breast, ovary, prostate and stomach carcinoma
key finding of splenic infarct
extension of abnormal parenchymal zone to an intact splenic capsule
complications of splenic infarctions
subcapsular hematomas, infection, splenic rupture with hemoperitoneum
small foci of hemosiderin resulting from focal hemorrhages in the spleen caused by portal hypertension
Gamma-Gandy bodies or siderotic nodules
most common primary neoplasm of speen
hemangioma
very rare but is still most common malignancy arising in the spleen. tumor is aggressive, usually presenting with widespread metastases especially to the liver
angiosarcoma
1/4 of splenic angiosarcoma present with
spontaneous splenic rupture
patients with exposure to this substance has increased risk for splenic angiosarcoma
thorotrast exposure
false splenic cysts with fibrous walls that lack an epithelial lining. walls are thick and commonly become calcified
posttraumatic cysts
posttrauamatic splenic cysts occur from
previous hemorrhage, infarction or infection
true epithelial lined cysts that are probably developmental in origin
epidermoid cysts
bacterial splenic abscesses result from
hematogeneous spread of infection, trauma, or infarction
causes of splenic microabscesses
fungi, TB, pneumocystis jiroveci, histoplasmosis, CMV
size of splenic microabscesses
5 to 10 mm up to 20 mm
