Spleen

Question 1

Spleen trivia:

1. At what age does the spleen reach normal adult size?
2. In HU, how does the spleen differ from liver?
3. Most splenic lesions are benign except for these 3…
4. Splenic appearance on MR.
5. Most common cystic lesion?
   
   1. Most common benign neoplasm?
   2. Most common malignant tumour?
6. Most common cause of splenomegaly?

Answer 1

1. 15 yrs.
2. Spleen 20 HU < liver.
3. Malignant splenic lesions:
   
   1. Lymphoma
   2. Angiosarcoma
   3. Mets
4. T1 dark relative to liver; T2 bright; restricts diffusion, just like a big lymph node.
5. Post-traumatic cyst.
   
   1. Hemangioma.
   2. Lymphoma.
6. Congestive: PHTN, heart failure.

Question 2

Congenital splenic variants/anomalies: splenule/accessory spleens:

1. What nucs exam can differentiate these from an enlarged pathologic LN?
2. What can happen to one of these post-splenectomy?
3. What % of pts w/accessory spleens have intrapancreatic accessory spleens?

Answer 2

1. Tc-99m sulfur colloid.
2. They can enlarge and then the original hematologic disease process can recur in it, e.g., ITP or autoimmune hemolytic anemia.
3. ~17%

Question 3

Congenital splenic variants/anomalies: splenosis:

1. When does this occur?
   
   1. Rare occurrence w/a specific type of trauma.
2. How does splenosis differ from polysplenia or accessory spleens (splenunculi)?
3. Typical location?
4. What % of traumas have these?
5. How to Dx?

Answer 3

1. Post-trauma, or post-splenectomy, a smashed spleen auto-implants then recruits blood supply.
   
   1. Thoracic splenosis: rare, but occurs following blunt trauma causing splenic injury + L hemidiaphragmatic rupture (see below).
2. This is not congenital and does not retain arterial supply from the splenic artery. This is also not composed of normal splenic tissue.
3. LUQ.
4. 40-60%.
5. Tc-99m sulfur colloid: as long as the deposit is at least 2cm diameter, or Tc-99m heat-damaged RBC (gold standard).

Question 4

Congenital splenic variants/anomalies: wandering spleen

1. What is this associated with?
2. What can the unusual location of a wandering spleen lead to?
3. What can happen if there is a chronic, partial torsion?

Answer 4

1. Intestinal rotation abnormalities.
2. Torsion & infarction.
3. Splenomegaly +/- gastric varices.

Question 5

Benign non-cystic splenic lesions: hemangioma

1. What is its notoriety?
2. Ix app?
3. Does it have the classic look of a hepatic hemangioma?

Answer 5

1. It’s the most common benign splenic neoplasm.
2. Well-marginated, smooth, enhances w/delayed washout.
3. Not necessarily, & especially if <2cm.

Question 6

Benign non-cystic splenic lesions: hamartoma

1. Commonality?
2. Ix?
3. When will they be hyperdense?

Answer 6

1. Rare.
2. Hypo or iso w/hetero enhancement.
3. Will be hyperdense if they contain hemosiderin.

Question 7

DDx cystic splenic lesions (mnemonic):

Answer 7

TEAM:

1. traumatic
2. echinococcal
3. abscess
4. mets

Question 8

Benign cystic splenic lesions: post-traumatic pseudocyst:

1. Notoriety.
2. Causes-5.
3. Real cysts or pseudo? Why?
4. Typical features.

Answer 8

1. Most common splenic cystic lesion (80%).
2. Trauma, infarction, infection, hemorrhage, extension from pancreatic pseudocyst.
3. Pseudocysts as they have no lining epithelium.
4. Hypo-attenuating, thick-walled +/- peripheral calcs.

Question 9

Benign cystic splenic lesions: congenital true, primary (aka epithelial, epidermoid) cyst:

1. Notoriety.
2. Origin?
3. Lining cells?
4. Typical size?
5. Solitary/multifocal?
6. Typical app.

Answer 9

1. 2nd most common splenic cystic lesion after post-traumatic cyst.
2. Congenital.
3. Epithelial, so these are true cysts.
4. >10cm usually.
5. Usually solitary.
6. Unilocular fluid, w/thin/smooth walls & no enhancement.

Question 10

Benign cystic splenic lesions: lymphangioma

1. Commonality?
2. Demographic?
3. Path? Cyst wall cells.
4. Solitary/multiple?
5. Typical app, location?

Answer 10

1. Rare.
2. Kids–rarely reported in adults.
3. Abnormal dilation of lymphatic channels. Endothelial.
4. Typically solitary, but if diffuse can be 2dry to lymphangiomatosis.
5. Lobulated, multiloculated (but can be unilocular), peripheral lesions w/o solid component or significant enhancement.

Question 11

Benign cystic splenic lesions: peliosis

1. Common?
2. Path?
3. In what organ does this usually occur?
   
   1. If you see it in the spleen where else will it be?
   2. Is it commonly isolated to the spleen?
4. 5 RFs.
5. Sequela & imaging finding?

Answer 11

1. Rare.
2. Multiple blood-filled cyst-like spacees.
3. Liver.
   
   1. If it’s in the spleen it’ll be in the liver as well.
   2. It’s never in the spleen, alone.
4. RFs:
   
   1. women on OCPs
   2. men on anabolic steroids
   3. AIDS pts
   4. renal xplant pts: up to 20%
   5. Hodgkin lymphoma pts
5. Hemorrhage, large volume hemoperitoneum.

Question 12

Benign cystic splenic lesions: Littoral cell angioma

1. Path.
2. Clinical associations-2
3. Typical app:
   
   1. US
   2. CT
   3. MR

Answer 12

1. Benign 1° vascular tumour; Littoral cells line the sinusoids of red pulp, hence they’re vascular.
2. Crohn’s, hypersplenism.
   
   1. US: bright masses.
   2. CT: splenomegaly + multiple hypoattenuating (late PV phase) nodules.
   3. MR: T1/T2 dark from hemosiderin

Question 13

Inflammatory splenic lesions: sarcoidosis

1. In what % of sarcoid pts is the spleen involved?
2. What is the sole sign, usually?
   
   1. What is an alternate appearance & why does this occur?
3. Rarely, what is the sequela?
4. What is the most common site of sarcoidosis in the GI tract?
   
   1. What can this cause?

Answer 13

1. The majority: 50-80%.
2. Splenomegaly.
   
   1. Hypodense nodules, 1-2cm, when aggregates of granulomatous tissue congregate in the spleen.
3. Splenomegaly & hemorrhage.
4. Gastric antrum.
   
   1. Gastric outlet obstruction.

Question 14

Splenic infection: general:

1. In an immunocompetent pt, what kind of bug causes an abscess?
   
   1. What is the classic bug?
   2. In what 2 settings does this develop?
2. In an immunecompomised pt, what are the 4 classic bugs?
   
   1. Typical Ix app?
   2. What US app do fungal infections have?

Answer 14

1. Aerobic bacteria
   
   1. Salmonella
   2. In the setting of splenic damage, i.e., trauma or sickle cell (recall that sickle cell pts get a lot of Salmonella).
2. Fungal, TB, MAI (mycobacterium avium-intracellulare), PCP.
   
   1. Multiple small micro-abscesses.
   2. Targetoid.

Question 15

Splenic infection calcifications:

1. What is the most commonly detected splenic infection?
   
   1. Appearance?
   2. What bug shows a similar appearance but much less common in the US?
2. What is another common cause of calcified splenic lesions, and appearance?

Answer 15

1. Histoplasmosis.
   
   1. Multiple round calcs.
   2. TB.
2. Brucellosis.
   
   1. Solitary, 2cm or larger. May have a low density centre, encircled by calcification, showing a “bulls eye” appearance (see below).

Question 16

Malignant splenic lesions: angiosarcoma

1. ​Commonality?
2. RF
3. App: CT.
4. Sequela.
5. Prognosis?

Answer 16

1. Rare but the most common primary malignant splenic mass.
2. RF: thorotrast.
3. CT: large, necrotic, poor contrast enhancement.
4. 30% spontaneously rupture.
5. Aggressive w/poor prognosis.

Question 17

Malignant splenic lesions: splenic lymphoma:

1. Commonality?
2. Most common Ix finding.
3. Patterns in Hodgkins vs. NHL.
4. Ix:
   
   1. CT
   2. MR
   3. PET

Answer 17

1. Most common non-primary splenic malignancy.
2. Splenomegaly–often there will be no nodules.
3. Patterns:
   
   1. Hodgkins: have nodules.
   2. NHL: have non-nodules.
4. Ix:
   
   1. CT: splenomegaly or low density nodules.
   2. MR: T1 dark.
   3. PET hot.

Question 18

Malignant splenic lesions: splenic mets:

1. The most common splenic met?
   
   1. Typical app?
2. Other common splenic mets.

Answer 18

1. Melanoma.
   
   1. Low attenuation, almost like a cyst.
2. The most common mets: breast, lung.

Question 19

Miscellaneous splenic lesions: splenic artery aneurysm:

1. Notoriety?
2. In what 2 cases can pseudoaneurysm occur?
3. In what pop is incidence higher?
   
   1. 2 details regarding the above pop.
4. At what size are they repaired?

Answer 19

1. The most common visceral arterial aneurysm.
2. Trauma, pancreatitis.
3. Women who have had >=2 pregnancies.
   
   1. They are 4x more likely to get them, 3x more likely to rupture.
4. 2-3cm.

Question 20

Miscellaneous splenic lesions: splenic vein thrombosis:

1. 3 RFs.
2. What can this lead to?

Answer 20

1. Pancreatitis, diverticulitis, Crohn’s.
2. Isolated gastric varices.

Question 21

Miscellaneous splenic lesions: splenic infarct:

1. What is the classic cause (on MCQ exams)?
2. Classic Ix finding?
3. 2 RFs?
   
   1. For one of them, when do infarcts often occur?

Answer 21

1. Sickle cell.
2. Peripheral, wedge-shaped, low attenuation lesion, often multifocal.
3. Cardiac souces of emboli; splenomegaly.
   
   1. Splenomegaly + hypotension.

Question 22

Miscellaneous splenic lesions: gamna-gandy bodies

1. Pathologically, what are these?
2. What clinical association?
3. MR appearance?
   
   1. Which MR sequence is most sensitive?

Answer 22

1. Siderotic nodules, i.e., small hemorrhagic foci.
2. PHTN.
3. T2 dark.
   
   1. GRE for susceptibility.

Question 23

Overview of splenic trauma:

1. In what phase is a trauma scan done & why?

Answer 23

1. PV phase (70 sec) as it is impossible to tell if the tiger-striped arterial phase spleen is lacerated.

Question 24

DDx small spleen

Answer 24

1. Sickle cell: small, calcified; auto-splenectomy (see below).
2. Post-radiation
3. Post-Thorotrast: causes cholangio too
4. Malabsorption syndromes: UC > Crohns.

Question 25

**DDx: splenomegaly**

Answer 25

1. Passive congestion: PHTN, heart failure, splenic vein thrombosis. 2. Lymphoma 3. Leukemia 4. Gauchers 5. Sarcoid: more common in women & w/respiratory complaints. 6. Myelofibrosis

Question 26

What is the best test to confirm the etiology of this lesion?

Answer 26

* Heat-damaged RBC scintiscan. * This is the most specific modality for the diagnosis. * This is an intra-pancreatic accessory spleen. * This would be FDG avid on PET but could be confused w/tumour.