Gallbladder, Liver, Pancreas And Spleen

GALLBLADDER 

functions as a reservoir for bile produced by the liver. It is 7-10 cm long, 3 cm wide at its broadest measure, and has a capacity of 30-50 mL

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divided into 3 regions: fundus, body, and neck

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bile produced by the left and right portions of the liver travel through the right and left hepatic ducts (1-2 mm in diameter). These two ducts join to form the common hepatic duct the common hepatic duct lies anterior to the portal vein and to the right of hepatic artery the common hepatic duct descends roughly 3 cm before the cystic duct (3-4 cm long) from the gallbladder joins it from the right

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portions of the duodenum are labeled in white. at the head of the pancreas, the common bile duct meets the pancreatic duct, and they exit into the second part of the duodenum, forming the hepatopancreatic ampulla (ampulla of Vater)

Adenomyomatosis  

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the common bile duct passes posterior to the first portion of the duodenum. It then descends via a groove on the superolateral portions of the posterior head of the pancreas sometimes traveling through the pancreas head. The four

one of the many causes for gallbladder wall thickening pathologically, it is identified by proliferation of the gallbladder mucosa with diverticular outpuochings known as Rokitansky-Aschoff sinuses typically cholesterol deposits are seen within the gallbladder wall and cause a comet tail artifact

Causes of GB wall thickening  biliary causes include: -acute cholecystitis, gall bladder carcinoma, polyps, as well as adenomyomatosis

nonbiliary causes include: -CHF, hepatitis, pancreatitis as well as AIDs cholangiopathy 

Acute Acalculous Cholecystitis  

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represents inflammation of the gallbladder in the absence of demonstrated calculi the disease process is distinct from the calculous variety, in which the primary initiating event is believed to be obstruction of the cystic duct typically occurs as a secondary event in patients who are hospitalized and acutely ill from another cause

Pathophysiology  at least 3 mechanisms a. systemic mediators of inflammation and trauma b. biliary stasis c. generalized or localized ischemia  in turn, the mechanisms often result in functional or secondary mechanical obstruction of the cystic duct from inflammation and bile viscosity Sonographic signs compatible with acalculous cholecystitis

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gallbladder wall thickening mucosal irregularity luminal distention increased bile density (biliary sludge) intramural or intraluminal gas intraluminal hemorrhage localized pericholecystic fluid collections inflammatory infiltration of pericholecystic fat indistinctiveness of the liver-gallbladder interface

Acute Cholecystitis sonographic criteria for acute cholecystitis -a thickened gallbladder wall (normal GB wall- <3 mm)  other sonographic findings -gallstones -positive Murphy’s sign -pericholecystic fluid as well as sonolucencies within the gallbladder wall (indicates gallbladder wall edema) 

Complications  empyema  gangrene  perforation       

gallbladder wall thickening sonographically localized tenderness over the GB subserosal edema pericholecystic fluid gallbladder distention biliary sludge presence of gas

CT findings

Epigastric Pain

Chronic Cholecystitis with GB polyps 

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chronic inflammation of the gallbladder results from recurrent attacks of acute cholecystitis fibrotic reaction usually causes the gallbladder to become small and contracted

Diffuse Wall Thickening

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most frequent gallbladder wall abnormality detected by ultrasound the wall is >3mm thick this appearance is neither sensitive nor specific for an inflammatory process

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Case -patient is a 72-year old woman who presents with nausea and vomiting

75-80% of gallstones are of the cholesterol type 10-25% of gallstones are bilirubinate of either black or brown pigment in Asia, pigmented stones predominate, although recent studies have shown an increase in cholesterol stones in the Far East

Porcelain Gallbladder 

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has been termed calcifying cholecystitis, cholecystopathia chronic calcaria, or calcified gallbladder are 5 times more common in women than in men most often considered a sequel of lowgrade chronic inflammation some have postulated that it is secondary to intramural hemorrhage or an imbalance in calcium metabolism

Complications  biliary colic- 56 %  acute cholecystitis- 36 %  acute pancreatitis- 4 %  choledocholithiasis- 3 %  gall bladder cancer- 0.3 %  cholangitis- 0.2 %

Gall Stones

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Cholelithiasis 

is the pathologic state of stones or calculi within the gallbladder lumen

appear as single or multiple filling defects within the gallbladder and are densely calcified, rim calcified, laminated, or have a central nidus of calcification

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associated with chronic gallbladder inflammation and gall stones in 95 % of cases it appears as an echogenic arc with dense posterior shadowing

Carcinoma of the Gallbladder  

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stones also may present as a soft-tissue density or a lucent filling defect within the bile. Some stones may contain air

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most gallstones have no signal on MRI and present as signal void-filling defects within the gallbladder

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on T2-weighted sequences where signalvoid stones are contrasted against highsignal bile on T1 weighted sequences, bile usually shows a homogenous low signal

signal-void stones also may be apparent on T1-weighted images high signal may be seen occasionally on T2-weighted images within stones that contain bile within clefts stones with high fatty acid content may demonstrate high signal on T1-weighted images

Porcelain gallbladder along with distention and filled with sludge and calculi

the most common primary hepatobiliary carcinoma the fifth most common malignancy of the GI tract predominantly affects older persons with long-standing cholecystolithiasis GB epithelial tumors tend to behave similarly to other GI adenocarcinomas GB tumors occur in the fundus in 60 % of patients, in the body in 30 %, and neck 10 % early lymphatic spread occurs to the retroperitoneal, right celiac, and pancreaticoduodenal nodes direct invasion of the liver, extrahepatic biliary ducts, and duodenum, and colon occurs intraperitoneal seeding may occur

Ultrasound findings  GB wall thickening  single or multiple intraluminal mass  extraluminal mass extending to the liver  polyps larger than 1 cm in diameter Extraluminal mass extending to the liver  this often is accompanied by a large mass replacing the GB fossa  the mass often is complex with areas of necrosis visible  this is the most common manifestation of GB carcinoma, accounting for 40-65 % of GB carcinomas

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US shows echogenic mass adherent to gallbladder fundus (arrows). CT shows enhancing mass within the gallbladder (arrows) with involvement of the liver (arrow head)

3-Left inferior lateral subsegment 4a-Left superior medial subsegment 4b-Left inferior medial subsegment 5-Right inferior anterior subsegment 6-Right inferior posterior subsegment 7-Right superior posterior subsegment 8-Right superior anterior subsegment

Bacterial (Pyogenic) Abscess  

LIVER

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unique in having a dual blood supply - 75 % originating from the portal venous system and -25 % arising from the hepatic artery  the hepatic veins are responsible for drainage of filtered blood from the liver into the IVC 

80-85 % of all abscesses are bacterial in origin bacteria gain access to liver via the portal or biliary system. Possible causes are iatrogenic, biliary disease, diverticular disease, trauma, and inflammatory bowel disease E. coli and anaerobes are the two most common offending agents in pyogenic abscess most pyogenic abscesses occur in the right lobe

Radiogrpahic Findings (US)  heterogenous, rounded masses with irregular, thickened walls and poor peripheral definition  fluid and debris inside the abscess can create internal echoes  gas-containing lesion also has acoustic shadowing CT

3 Functional Lobes  right  left  caudate the right and left lobes are further divided into 2 segments each: -the anterior and posterior segments of the right lobe -the medial and lateral segments of the left lobe 

Segments

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heterogenous lesion with irregular margin (arrowhead) and possible peripheral enhancement internal septations or papillary projections 20 % contain gas

Amebic Abscess  

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1-Caudate lobe 2-Left superior lateral subsegment

trnasmitted by fecal-oral route the organism, E. histolytica, first infects the colon, then gains access to the liver via portal venous system patients generally present with right upper quadrant pain

Radiographic Findings (US & CT)  indistinguishable from bacterial abscess. Tends to be peripheral in location

CT Findings

Diffuse Hepatic Disease Cirrhosis Causes  alcohol  alpha 1-antitrypsin  postnecrotic (hepatitis)  metabolic disease: Wilson, hemochromatosis, glycogen storage disease  congestive heart failure Pathology  hepatocyte necrosis  fibrosis  nodular regeneration Radiographic Findings

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generally non specific including: a peripherally based, round or oval low density lesion which often demonstrates a peripheral rim of slightly higher attenuation the peripheral rim will often enhance with contrast administration

Echinococcal Abscess  

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dogs are the main intermediate hosts of hydatid disease eggs get ingested, hatch in the stomach and duodenum, travel to the liver via portal venous drainage, encyst in the liver and grow slowly the cysts can exert mass effect on the surrounding liver and biliary system. The right lobe of the liver is most frequently involved the cysts can rupture into the pleural cavity, peritoneal cavity, alimentary canal, or biliary tree, causing profound shock, peritonitis, and anaphylaxis

Radiographic Findings (US)

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double-layered cyst, “classic” double-line sign, water lily sign, racemose

Signs   

of advanced necrosis liver surface nodularity contracted liver with ascites atrophy of the posterior segments (VI, VII) of the right lobe  enlarged caudate lobe (I) and lateral segments (II, III) of the left lobe  prominent umbilical vein  irregular enhancement

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US- advanced cirrhotic liver appears to be nodular, irregular, and contracted with relatively enlarged caudate lobe (C) and lateral segment (L) of the left lobe. Fatty infiltration and fibrosis give a coarse echotexture of the liver parenchyma

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Contrast CT: areas of fibrosis and regeneration may become isodense to parenchyma. The surface of the liver may be very nodular in cirrhosis

Diffuse Fatty Infiltration 

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development of collateral vessels in portal hypertension splenomegaly and the presence of ascites

a reversible process in which triglyceride accumulates diffusely in hepatocytes causing abnormal appearance on imaging normally, less than 5 % of the liver is composed of fat. In diffuse fatty infiltrated liver, fat can make up to 50 % of the liver tissue commonly seen in acute or chronic alcohol abuse (most common), obesity, diabetes, cystic fibrosis, tetracycline, steroids, chemotherapy, malnutrition, and hyperalimentation clinically, patients are asymptomatic. Liver can be enlarged but without splenomegaly

Radiographic Findings (US)

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the liver has increased focal or diffuse echogenicity when compared to the surrounding organs such as the kidneys

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Noncontrast CT- the liver looks hypodense to the spleen due to fatty infiltration, making the hepatic vasculature more prominent

Hemochromatosis

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iron overload leads to deposition in the liver. The liver can be enlarged primary hemochromatosis: an autosomal recessive disease that has abnormal absorption of iron in the intestine and thus causes iron to be deposited in hepatocytes, spleen, pancreas, and the myocardium secondary hemochromatosis: caused by multiple transfusions with deposition of iron in the reticuloendothelial cells of the liver and the spleen. However, the pancreas is not usually involved. If the pancreas is involved, the hemochromatosis is usually of the primary type

CT: hyperdense liver (>75 HU). There are similar findings in Wilson’s disease, amiodarone toxicity, and previous thorotrast exposure

T1 and T2 weighted MRI: liver and spleen are hyperintense (very dark liver) compared with adjacent muscles owing to paramagnetic effect. Normally, the signal intensity of the liver parenchyma is equal to or slightly greater than that of muscle

Simple Cysts   

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the most common liver masses may be solitary or multiple cysts are found in 2-10 % of population, has increased frequency with age and is more common in females aged 50-70 true hepatic cysts have bile duct origin and cuboidal epithelial lining. They are

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idiopathic, usually asymptomatic and variable in size. They cannot be distinguished from cysts that arise from prior hematomas or abscesses they can be associated with other disease processes such as tuberous sclerosis and polycystic kidney disease 40 % of patients with polycystic kidney diseae have liver cysts 60 % of patients with multiple liver cysts have polycystic kidney disease

Radiographic Findings

US (95-99 % accurate)  anechoic  posterior enhancement (increased transmitted sound)  well-defined or imperceptible walls

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Non-contrast CT: density of less than 20 HU, well-defined margins, no perceptible wall (arrow)

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Contrast CT: no enhancement after contrast administration

MRI

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T1 weighted- homogeneously hypointense (arrowhead)

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T2 weighted- homogeneously hyperintense (arrow) due to water property (comparable to the intensity of CSF or gallbladder bile

Differential Diagnosis  cystic liver mass with internal echoes, thick septations, or a perceptible wall noted on US include -hemorrhagic cyst -abscess -echinococcal cyst -biliary cystadenoma -cystic metastasis (e.g. ovarian) -HCC with necrosis

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US: hyperechoic and well-defined

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T1 weighted MRI- hypointense to liver (arrows). If gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA) is used, peripheral enhancement is seen initially with central enhancement within 15-30 minutes. Enhancement is persistent

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T2-weighted MRI- hyperinetense to the liver (just like a cyst; arrows). Looks as bright as a light bulb! Intensity is as high as that of pure fluid (CSF or bile)

Hemangioma 

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is a benign proliferation of vascular tissue lined with endothelium which has slow hepatic arterial blood flow two types are capillary (more common) and cavernous occurs in the right lobe can easily be confused with metastases or hepatoma the most common cause of a hyperechoic liver mass on US large hemangioma may appear heterogenous. There may be thrombosis or a central stellate scar with a giant hemangioma

Focal Nodular Hyperplasia 

most likely seen in young women (3 %)

Pathology  a non-capsulated nodular mass  was thought to be a vascular/hamartomatous malformation  is composed of normal hepatocytes, Kupffer cells, and bile ducts but arranged abnormally

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is less than 5 cm in diameter, most commonly found peripherally in the right lobe classic appearance: solitary, wellcircumscibed mass with a central stellate scar of fibrosis even though the central scar is seen in only 20 % of the cases

Hepatocellular Carcinoma (HCC) • 

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Non-contrast- the lesion has low attenuation (arrows) compared with the normal liver. The central stellate scar may also show low attenuation Contrast CT: the lesion shows homogenous enhancement early in arterial phase (arrows) with prompt wash out. The central stellate scar will not enhance.

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the most common primary hepatic tumor and one of the most common cancers worldwide a primary malignancy of hepatocyte origin

3 Growth Patterns of HCC • • •

Solitary mass – often large Multifocal or Nodular Pattern – multiple nodules Diffuse – multiple, small foci scattered diffusely throughout liver

US Findings •

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T1-weighted MRI: The lesion is hypoisointense to the normal liver. The central scar enhances with Gd-DTPA.

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T2-weighted MRI: The lesion is isointense to slightly hyperintense to liver. The central scar is hyperintense to the liver (arrows). (In contrast to hypointense appearance of the central scar in large hemangioma)

Small HCCs can be homogenously hyperechoic and can mimic hemangioma. This can result when a large proportion of fat is present in the tumor Small HCCs can appear hypoehcoic with larger HCCs frequency mixed in echogenicity.

In the Portal Venous Phases •

Small lesions may be isodense or hypodense and difficult to see, since the remainder of the liver increases in attenuation.

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Larger lesions with necrotic regions remain hypodense.

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In children the most common liver metastases are from a neuroblastoma, Wilm’s tumor or leukemia.

Contrast CT: dense diffuse non-uniform enhancement in arterial phase; some lesions are hypervascular Causes of Echogenic Metastases •

MRI •

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Mucinous adenocarcinoma of the colon, Pancreatic carcinoma (usually hypoechoic but possibly becoming echogenic as calcification occurs), Gastric carcinoma (usually hypoechoic), HCC, Neuroblastoma, Cholangiocarcinoma, Treated Breast Carcinoma, Renal cell Carcinoma, Carcinoid, Choriocarcinoma, Pancreatic Islet Cell tumors, Wilm’s Tumor (usually spread to the lungs), Kaposi sarcoma, Myeloma deposit, Hepatic chloroma

T1-weighted: usually hypointense to normal liver. When fatty change, fibrosis, or copper is present, variable signal can be seen. With Gd-DTPA, hypervascular lesions enhance early in the arterial phase.

Causes of Hypoechoic Metastases •

Liver Metastasis • •

The liver is the most commonly involved organ by metastatic disease, after the lymph nodes. The most common primary sites are the eye, colon, stomach, pancreas, breast and lung.

Lymphoma (especially AIDS related), HCC, Pancreatic carcinoma, Lung (particularly adenocarcinoma), Cervix, Melanoma, Nasopharyngeal carcinoma, Kaposi sarcoma (rare, most are hyperechoic), Myeloma deposits, Cystic liver metastases, Mucinous cystadenocarcinoma colon, Cystadenocarcinoma ovary. Cystadenocarcinoma pancreas, Leiomyosarcoma, Squamous cell carcinoma, Testicular CA, Carcinoid, Graunulosa cell ovarian tumor.

Cystic metastases

Two groups of patients tend to get cystic metastases: (1) Patients who have a primary neoplasm with a cystic component such as a mucinous cystadenocarcinoma of the colon, stomach, pancreas, or ovary and, (2) Patients with metastases that are undergoing central necrosis, when lowlevel echoes and wall irregularity is seen. Squamous cell carcinoma, leiomyosarcoma, melanoma, and testicular carcinoma, have a propensity to undergo extensive central necrosis. Causes of Bull’s Eye or Target, Metastases •

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The halo is most probably related to a combination of compressed normal hepatic parenchyma around the mass and a zone of cancer cell proliferation The presence of a halo usually suggests aggressive behavior Bronchogenic carcinoma Breast and colon as well as Primary malignant liver neoplasms (eg. HCC) and Benign liver neoplasms (eg. Adenoma in glycogen storage disease)

Portal Vein Thrombosis Five causes of portal vein thrombosis: 1. 2. 3. 4. 5.

Pancreatitis Cirrhosis Hepatic or biliary surgery Hepatoma with tumor thrombus Hypercoagulable states

CT: example of carcinoma in the hepatic vein

Causes of heterogeneously Echogenic Liver Metastases • •

Breast, colon and/or rectum, stomach (especially anaplastic lesions) and cervix Other causes of heterogeneously liver metastases include the ff: HCC (especially when complicated with hemorrhage), carcinoid, melanoma, and bronchogenic carcinoma.

PANCREAS Acute Pancreatitis •

Common cause of pancreatitis include alcohol abuse, choledolithiasis, hypergylceridemia and hypercalcemia. Acute pancreatitis usually presents as an acute episode of upper abdominal pain, with or without accompanying GI symptoms.

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Other symptoms may include fever, hypotension, pulmonary edema or shock. Laboratory values reveal elevated WBC, serum amylase and pancreatic lipase. Initial treatment of pancreatitis includes NPO, NG suction, analgesics, parenteral or jejunal feeding. Prophylactic antibiotics may also be of benefit.

Ranson’s score estimates the life threatening complications or death in patients with acute pancreatitis using several factors at the time of admission and during the first 48 hours thereafter. Ranson’s Score Values at Admission

First 48 Hours

Age>55

Hct fall >10%

WBC >16,000/ml

Ca >8mEq/L

Glucose >200mg/dl

BUN rise > 5mg/dl

LDH>350 U/L

PaO2 < 60mmHg

AST > 250 U/L

Base defect > 4 mEq/L Fluid sequestration > 6L

Number of Criteria

Mortality

0-2

<5%

3-4

15-20%

5-6

40%

≥7

>99%

associated with pancreatic fat infiltration Grad eD

Single fluid collection

Grad eE

Two or more fluid collections.

associated with acute pancreatitis

Nausea, vomiting with abdominal pain that radiates to the back

Acute Necrotizing Pancreatitis •

Balthazar et al developed a classification system for patients with acute pancreatitis based on radiologic findings

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Pancreatic necrosis is a known complication of acute pancreatitis. Areas of necrosis are usually multifocal and rarely involve the entire gland. Necrosis develops earl in severe pancreatitis and is usually established within 96 hours of the onset of clinical symptoms.

Balthazar et al Radiographic Grading of Acute Pancreatitis G rade

Radiographic Findings

Prognosis

Grad eA

Normal appearing pancreas

Grad eB

Focal or diffuse enlargement of the pancreas

Mild, uncomplicated course

Grad eC

Pancreatic gland abnormalities

High risk of complications

Pancreatic Pseudocysts • •

The most common cystic lesions of the pancreas accounting for 75-80% of such masses A collection of amylase-rich, lipase-rich, and enterokinase-rich fluid

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Pancreatic Cancer

Most frequently located in the lesser peritoneal sac in proximity to the pancreas Large pseudocysts can extend to the paracolic gutters; pelvis; mediastinum Some are loculated

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Most Common Etiologies • • • •

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Chronic pancreatitis Acute pancreatitis and Pancreatic trauma In addition, pseudocysts are associated with pancreatic ductal obstruction and pancreatic neoplasms

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US Findings • • • •

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An anechoic structures associated with acoustic enhancement Well defined and round or oval, and they are contained within a smooth wall During the early phases, the more complex, with varying degrees of internal echoes Usually, this appearance results from the presence of necrotic pancreatic and peripancreatic debris and is more common in pseudocysts that form as a result of acute necrotizing pancreatitis than in others. The debris is cleared over time. The pseudocysts can appear more complex in 2 other instances: when hemorrhage occurs in the cyst or when infection of the cyst complicates the clinical course Color Doppler or duplex scanning should always be performed in cystic lesions to ensure that the lesion in question is not a giant pseudoaneurysm Abdominal CT is an excellent choice for imaging acute fluid collections and pancreatic pseudocysts CT characteristics of an acute fluid collection include low attenuation and a homogenous appearance CT attenuation values may measure greater than 20-30 HU because of the presence of necrotic pancreatic or peripancreatic debris or blood within the confines of the acute fluid collection.

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The findings of an invasive hypodense mass in the had of the pancreas which involves the SMV and SMA along with enlarged lymph nodes are most suggestive of pancreatic CA The 5th most common cause of cancer deaths It is approximately twice as common in males compared to females Patients are usually greater than 50 years old Greater than 90% of pancreatic cancers are ductal adenocarcinoma and its variants Most of the remaining 5-10% are islet cell tumors Arises in the head of the pancreas 70% of the time, in the body 20%, and in the tail 10%. Abdominal pain and weight loss are present in greater than 75% of patients with pancreatic cancer, and jaundice is present in greater than 80% of patients with pancreatic heat tumors secondary to biliary obstruction

CT • •

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The best modality for imaging the pancreas A mass deforming the size and contour of the pancreas is the most common finding for ductal cell carcinomas occurring in 96% of the cases A central zone of decreased attenuation is present in 83% of pancreatic head and 60% of pancreatic body carcinomas CT can be used for staging purposes with the findings of the retroperitoneal extension, major vascular involvement, invasion of contiguous organs, ascites, LN and distant metastases suggesting unresectability.

Adenocarcinoma • • • •

The fourth most common cancer The prognosis of the disease is poor and very few patients survive longer than one year Major role of imaging once the primary diagnosis has been made is to “stage” the disease to determine operability The loss of the fat plane indicates encasement of the artery making the patient uncurable

CT Findings of Pancreatic CA • • • • • • •

Alteration in the morphology of the gland with abnormalities of CT attenuation values Obliteration of peripancreatic fat Loss of sharp margins with surrounding structures Involvement of adjacent vessels and regional lymph nodes Pancreatic ductal dilatation Pancreatic atrophy and, Obstruction of the common bile duct (CBD)

Mucinous Cystic Neoplasm

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US Features • • • • •

Mucinous Cystic Tumors • • • • •

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So called macrocystic cystadenomas or, cystadenocarcinomas. Predominate in the body and tail of pancreas, have a strong female predilection Most common of cystic pancreatic tumors, accounting for 45-50% of tumors Multiloculated tumors with a characteristic smooth glistening surface Arise from oversecretion of the mucus of the hyperplastic columnar lining of the ducts. The cysts contain thickened viscous material, which can also be hemorrhagic Nonenhanced CT scans show a welldefined unilocular or multilocular, externally smooth, round-to-ovoid mass with fluid attenuation The attenuation values of the multilocular cysts vary according to the degree of hemorrhage or protein in the mucoid cysts Larger cysts may demonstrate small daughter cysts along its internal surface. Typically, they show a well defined, multilocular cystic mass with thick internal mass septae separating the separating the different cystic cavities of varying sizes. The cysts are 2-26cm.

Visualization of the nodule with irregular borders of the septae and calcification which is curvilinear or punctate and confined to the cyst wall or septa CECT show enhancement of the cyst wall, internal septations, mural nodules, and other intracavitary projections CT may also allow the identification of solid components associated with cystic elements, which are features of borderline or malignant tumors but not benign variants. MCN’s develop predominantly in the tail of the pancreas (>90%) CT more clearly demonstrates enhancement of the cystic walls and septa

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Usually larger than 5cm The walls are composed of thick, fibrous stroma sometimes containing dystrophic calcification A large cystic mass sometimes with numerous septa and debris The tumor may be 2-23cm, and they usually have sharply marginated walls and smooth borders Typically show a multilocular, fluidcontaining mass with good transmission and strong acoustic enhancement Compared with serous cystic tumors, the cysts in MCNs are larger (>20mm in diameter) and less numerous (usually <6). CT-guided aspiration of the cyst can provide further diagnostic clues and enable their differentiation from other pancreatic cystic masses (eg, pseudocyst, serous cystadenoma, and solid and pseudopapillary neoplasm) MCN cyst fluid typically has a high viscosity, low amylase levels, and high CEA and carbohydrate antigen (CA) 72-4 levels, and they may show malignant

cytology in patients with mucinous cystadenocarcinomas. Periodic Acid-Schiff (PAS) and May Grunwald/Giemsa (MGG) stains are usually positive for extracellular as well as intracellular mucin.

Mucinous Cystic Neoplasm Intraductal Papillary Mucous Neoplasm • • •

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Papillary neoplasm that arises within the MPD or its branches The tumor hypersecretes mucin, which often leads to duct dilatation and/or chronic obstructive pancreatitis Are premalignant and may histologically demonstrate areas ranging from hyperplasia to carcinoma within in a single tumor The tumors generally show intraluminal, longitudinal growth but is usually slow to invade periductal tissues radially and slow to metastasize. Most commonly localized to the head of the pancreas, but they may occur at any site along the pancreatic ductal system Ductal dilatation is often impressive any may mimic MCNs on CT scans Is recognized as predominantly a solid tumor with a central cyst. The cystic variety consists microscopically of cyst like spaces with papillary protrusions.

Hypervascular tumor in the pancreatic tail with sunburst calcification. Note the Swiss-cheese enhancement.

Intraductal Papillary Mucinous Tumor

SPLEEN Accessory Spleens • In these cases, the findings on ERCP may be diagnostic. Rarely, segmental pancreatic duct dilatation may acquire a cystic appearance, whereas the MPD and the rest of the pancreas appears normal.

Microcystic Adenoma •

Cystic mass in the region of the tail of the pancreas.

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Or splenculi, are relatively commonly encountered “normal” anatomic variants Estimated to be present in approximately 10% of the population May be single or multiple in occurrence Are most frequently discovered in the vicinity of the splenic hilum or elsewhere within the gastrosplenic ligament They may, however, be found along the omentum, or anywhere else within the peritoneal cavity

CT Findings

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Attenuation and contrast-enhancement characteristics that are identical to those of normal spleen Measures approximately 1.0-1.5cm in diameter, but may range in size a few millimeters to several centimeters (2.3) Resection of all accessory spleens is recommended at the time of the splenectomy, as cases of accessorysplenic hypertrophy have been described subsequent to removal of the “main” spleen

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An example of calcified splenic cyst shown first on plain radiograph (left) with a coronal CT construction (right). Note the clear demarcation of the calcified cyst capsule.

Accessory Spleen (s)

Metastases: the axial CT images demonstrates multiple hypoenhancing lesions in the spleen consistent with metastatic CLL.

Splenic Cysts

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The differential diagnosis of large splenic cysts should include posttraumatic cysts (most common), epidermoid cysts, abscess, pancreatic pseudocyst, echinococcal cysts, lymphoma, infarction or cystic lymphangiomas (less common). Splenic cyst shown below as imaged on US.

Images of splenic metastasis visualized on US. Careful ultrasound examination can determine if these are cysts with increased through transmission of echoes versus solid metastatic lesions.

Opportunistic infection in AIDS patients (Pneumocystis carinii) Traumatic Vascular o “phleboliths” o Post-ischemic/infarction o

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Lymphoma •

Lymphomas is the most common malignant tumor of the spleen. Typically, lymphatic drainage to the spleen serves as the primary mechanism by which extranodal lymphomas of varying types by which extranodal lymphomas of varying types disseminates to the spleen. Of the two broad types of lymphoma (B vs. T cell), B cell lymphomas Hodgkin’s and non Hodgkin’s disease are often diagnosed from splenic imaging. Primary splenic lymphoma (PSL) is a rare malignancy with a reported incidence of less than 1% of all lymphomas.

The plain film shown demonstrates numerous round calcifications diffusely distributed specifically within the spleen. The likely etiology of the calcified granulomata is Histoplasmosis, which have this characteristic appearance in comparison to microabscess.

Case 33-year old woman with fever of unknown origin. Patient is HIV +.

Case Twenty-three year old woman with non-Hodgkin’s lymphoma.

Pneumocystis carinii infection in the spleen • • •

Splenic Calcifications •

Infectious o Previous granulomatous disease (tuberculosis, histoplasmosis)

Important cause of pneumonia in an immunocmporomised host Common sites of dissemination include lymph nodes, liver, bone marrow, and spleen. Splenic pneumocystic carninii infections have been described typically as low attenuation lesion which may contain internal calcifications.

Differential diagnosis of cystic lesions

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Post traumatic Epidermoid Epithelial and Echinococcal cyst Abscess Lymphoma and Metastatic lesions may also appear as regions of decreased attenuation in the spleen that may mimic cystic lesions

Splenomegaly • • • •

lymphoma leukemia cirrhosis portal hypertension