Spleen Flashcards
Spleen trivia:
- At what age does the spleen reach normal adult size?
- In HU, how does the spleen differ from liver?
- Most splenic lesions are benign except for these 3…
- Splenic appearance on MR.
- Most common cystic lesion?
- Most common benign neoplasm?
- Most common malignant tumour?
- Most common cause of splenomegaly?
- 15 yrs.
- Spleen 20 HU < liver.
- Malignant splenic lesions:
- Lymphoma
- Angiosarcoma
- Mets
- T1 dark relative to liver; T2 bright; restricts diffusion, just like a big lymph node.
- Post-traumatic cyst.
- Hemangioma.
- Lymphoma.
- Congestive: PHTN, heart failure.

Congenital splenic variants/anomalies: splenule/accessory spleens:
- What nucs exam can differentiate these from an enlarged pathologic LN?
- What can happen to one of these post-splenectomy?
- What % of pts w/accessory spleens have intrapancreatic accessory spleens?
- Tc-99m sulfur colloid.
- They can enlarge and then the original hematologic disease process can recur in it, e.g., ITP or autoimmune hemolytic anemia.
- ~17%

Congenital splenic variants/anomalies: splenosis:
- When does this occur?
- Rare occurrence w/a specific type of trauma.
- How does splenosis differ from polysplenia or accessory spleens (splenunculi)?
- Typical location?
- What % of traumas have these?
- How to Dx?
- Post-trauma, or post-splenectomy, a smashed spleen auto-implants then recruits blood supply.
- Thoracic splenosis: rare, but occurs following blunt trauma causing splenic injury + L hemidiaphragmatic rupture (see below).
- This is not congenital and does not retain arterial supply from the splenic artery. This is also not composed of normal splenic tissue.
- LUQ.
- 40-60%.
- Tc-99m sulfur colloid: as long as the deposit is at least 2cm diameter, or Tc-99m heat-damaged RBC (gold standard).

Congenital splenic variants/anomalies: wandering spleen
- What is this associated with?
- What can the unusual location of a wandering spleen lead to?
- What can happen if there is a chronic, partial torsion?

- Intestinal rotation abnormalities.
- Torsion & infarction.
- Splenomegaly +/- gastric varices.
Benign non-cystic splenic lesions: hemangioma
- What is its notoriety?
- Ix app?
- Does it have the classic look of a hepatic hemangioma?
- It’s the most common benign splenic neoplasm.
- Well-marginated, smooth, enhances w/delayed washout.
- Not necessarily, & especially if <2cm.

Benign non-cystic splenic lesions: hamartoma
- Commonality?
- Ix?
- When will they be hyperdense?
- Rare.
- Hypo or iso w/hetero enhancement.
- Will be hyperdense if they contain hemosiderin.

DDx cystic splenic lesions (mnemonic):
TEAM:
- traumatic
- echinococcal
- abscess
- mets
Benign cystic splenic lesions: post-traumatic pseudocyst:
- Notoriety.
- Causes-5.
- Real cysts or pseudo? Why?
- Typical features.
- Most common splenic cystic lesion (80%).
- Trauma, infarction, infection, hemorrhage, extension from pancreatic pseudocyst.
- Pseudocysts as they have no lining epithelium.
- Hypo-attenuating, thick-walled +/- peripheral calcs.

Benign cystic splenic lesions: congenital true, primary (aka epithelial, epidermoid) cyst:
- Notoriety.
- Origin?
- Lining cells?
- Typical size?
- Solitary/multifocal?
- Typical app.
- 2nd most common splenic cystic lesion after post-traumatic cyst.
- Congenital.
- Epithelial, so these are true cysts.
- >10cm usually.
- Usually solitary.
- Unilocular fluid, w/thin/smooth walls & no enhancement.

Benign cystic splenic lesions: lymphangioma
- Commonality?
- Demographic?
- Path? Cyst wall cells.
- Solitary/multiple?
- Typical app, location?
- Rare.
- Kids–rarely reported in adults.
- Abnormal dilation of lymphatic channels. Endothelial.
- Typically solitary, but if diffuse can be 2dry to lymphangiomatosis.
- Lobulated, multiloculated (but can be unilocular), peripheral lesions w/o solid component or significant enhancement.

Benign cystic splenic lesions: peliosis
- Common?
- Path?
- In what organ does this usually occur?
- If you see it in the spleen where else will it be?
- Is it commonly isolated to the spleen?
- 5 RFs.
- Sequela & imaging finding?
- Rare.
- Multiple blood-filled cyst-like spacees.
- Liver.
- If it’s in the spleen it’ll be in the liver as well.
- It’s never in the spleen, alone.
- RFs:
- women on OCPs
- men on anabolic steroids
- AIDS pts
- renal xplant pts: up to 20%
- Hodgkin lymphoma pts
- Hemorrhage, large volume hemoperitoneum.

Benign cystic splenic lesions: Littoral cell angioma
- Path.
- Clinical associations-2
- Typical app:
- US
- CT
- MR
- Benign 1° vascular tumour; Littoral cells line the sinusoids of red pulp, hence they’re vascular.
- Crohn’s, hypersplenism.
- US: bright masses.
- CT: splenomegaly + multiple hypoattenuating (late PV phase) nodules.
- MR: T1/T2 dark from hemosiderin

Inflammatory splenic lesions: sarcoidosis
- In what % of sarcoid pts is the spleen involved?
- What is the sole sign, usually?
- What is an alternate appearance & why does this occur?
- Rarely, what is the sequela?
- What is the most common site of sarcoidosis in the GI tract?
- What can this cause?
- The majority: 50-80%.
- Splenomegaly.
- Hypodense nodules, 1-2cm, when aggregates of granulomatous tissue congregate in the spleen.
- Splenomegaly & hemorrhage.
- Gastric antrum.
- Gastric outlet obstruction.

Splenic infection: general:
- In an immunocompetent pt, what kind of bug causes an abscess?
- What is the classic bug?
- In what 2 settings does this develop?
- In an immunecompomised pt, what are the 4 classic bugs?
- Typical Ix app?
- What US app do fungal infections have?
- Aerobic bacteria
- Salmonella
- In the setting of splenic damage, i.e., trauma or sickle cell (recall that sickle cell pts get a lot of Salmonella).
- Fungal, TB, MAI (mycobacterium avium-intracellulare), PCP.
- Multiple small micro-abscesses.
- Targetoid.

Splenic infection calcifications:
- What is the most commonly detected splenic infection?
- Appearance?
- What bug shows a similar appearance but much less common in the US?
- What is another common cause of calcified splenic lesions, and appearance?
- Histoplasmosis.
- Multiple round calcs.
- TB.
- Brucellosis.
- Solitary, 2cm or larger. May have a low density centre, encircled by calcification, showing a “bulls eye” appearance (see below).

Malignant splenic lesions: angiosarcoma
- Commonality?
- RF
- App: CT.
- Sequela.
- Prognosis?
- Rare but the most common primary malignant splenic mass.
- RF: thorotrast.
- CT: large, necrotic, poor contrast enhancement.
- 30% spontaneously rupture.
- Aggressive w/poor prognosis.

Malignant splenic lesions: splenic lymphoma:
- Commonality?
- Most common Ix finding.
- Patterns in Hodgkins vs. NHL.
- Ix:
- CT
- MR
- PET
- Most common non-primary splenic malignancy.
- Splenomegaly–often there will be no nodules.
- Patterns:
- Hodgkins: have nodules.
- NHL: have non-nodules.
- Ix:
- CT: splenomegaly or low density nodules.
- MR: T1 dark.
- PET hot.

Malignant splenic lesions: splenic mets:
- The most common splenic met?
- Typical app?
- Other common splenic mets.
- Melanoma.
- Low attenuation, almost like a cyst.
- The most common mets: breast, lung.

Miscellaneous splenic lesions: splenic artery aneurysm:
- Notoriety?
- In what 2 cases can pseudoaneurysm occur?
- In what pop is incidence higher?
- 2 details regarding the above pop.
- At what size are they repaired?

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

Miscellaneous splenic lesions: splenic vein thrombosis:
- 3 RFs.
- What can this lead to?

- Pancreatitis, diverticulitis, Crohn’s.
- Isolated gastric varices.

Miscellaneous splenic lesions: splenic infarct:
- What is the classic cause (on MCQ exams)?
- Classic Ix finding?
- 2 RFs?
- For one of them, when do infarcts often occur?
- Sickle cell.
- Peripheral, wedge-shaped, low attenuation lesion, often multifocal.
- Cardiac souces of emboli; splenomegaly.
- Splenomegaly + hypotension.

Miscellaneous splenic lesions: gamna-gandy bodies
- Pathologically, what are these?
- What clinical association?
- MR appearance?
- Which MR sequence is most sensitive?

- Siderotic nodules, i.e., small hemorrhagic foci.
- PHTN.
- T2 dark.
- GRE for susceptibility.
Overview of splenic trauma:
- In what phase is a trauma scan done & why?
- PV phase (70 sec) as it is impossible to tell if the tiger-striped arterial phase spleen is lacerated.
DDx small spleen
- Sickle cell: small, calcified; auto-splenectomy (see below).
- Post-radiation
- Post-Thorotrast: causes cholangio too
- Malabsorption syndromes: UC > Crohns.

DDx: splenomegaly
- Passive congestion: PHTN, heart failure, splenic vein thrombosis.
- Lymphoma
- Leukemia
- Gauchers
- Sarcoid: more common in women & w/respiratory complaints.
- Myelofibrosis
What is the best test to confirm the etiology of this lesion?

- 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.