3. GI (The Spleen)

Question 1

Normal spleen trivia (6)

Answer 1

Reaches normal adult size at 15.
Contains red pulp and white pulp, causing striped appearance during arterial phase imaging.
Red pulp contains much blood, up to 1 litre at any time.
Spleen is usually 20HU denser than liver, and more echogenic too.
Splenic artery (arises from coeliac axis) is essentially an end vessel, with minimal collaterals.
Occlusion of splenic artery will therefore result in infarct of spleen.

Question 2

Splenic pathology - types (4)

Answer 2

Congenital
Acquired (sequelae of trauma or portal HTN)
Related to a mass.
Most things in the spleen are benign with exception of lymphoma or rare primary angiosarcoma.

Question 3

Normal spleen on MRI (3)

Answer 3

Essentially a big watery lymph node.
Bright on T2, dark on T1, diffusion restricts.

Question 4

Heterotaxia syndromes (4)

Answer 4

Left side vs right side.
Normal lungs: right has 2 fissures, left has 1.
If both lungs have 2 fissures, we have 2 right sides.
“Bilateral right sidedness”, therefore means patients won’t have a spleen because it’s a left sided structure.
The opposite is true, left sided heterotaxia will have polysplenia.

Question 5

Right vs Left sided heterotaxia

Answer 5

2 fissures in left lung vs 1 fissure in right lung.
Asplenia vs polysplenia.
Cardiac malformations vs biliary atresia
Reversed aorta/IVC vs Azygous continuation of IVC

Question 6

Accessory spleen (4)

Answer 6

Common.
Sulfur colloid could be used to differentiate splenule from enlarged pathologic lymph node.
Could hypertrophy and present as a mass after splenectomy (for ITP or autoimmune haemolytic anaemia).
Hypertrophy of accessory spleen can resilt in recurrence of original haematological disease process.

Question 7

Wandering spleen (4)

Answer 7

Normal spleen in unexpected location.
Due to laxity in the peritoneal ligaments holding the spleen, wandering spleen associated with abnormal intestinal rotation.
Unusual locations increase risk of splenic torsion and infarction.
Chronic partial torsion can lead to splenomegaly or gastric varices

Question 8

Trauma (3)

Answer 8

Spleen is commonest solid organ injured in trauma.
Can be life threatening as it holds a lot of blood.
Trauma scan is portal venous phase.

Question 9

Splenosis (4)

Answer 9

Occurs post trauma, damaged spleen implants, then recruits blood supply.
Implants are usually multiple and grow into spherical nodules, typically in peritoneal cavity of upper abdomen, but can be anywhere).
Surprisingly common, 40-60% of trauma.
Sulfur colloid or heat treated RBC to confirm the lesions are spleen and not other pathology.

Question 10

Gamma gandy bodies (Siderotic bodules) (3)

Answer 10

Small foci of haemorrhage in the splenic parenchyma, usually associated with portal HTN.
T2 dark. Gradient is most sensitive sequence.

Question 11

Sarcoidosis (spleen) (6)

Answer 11

Unknown aetoiology, causes noncaseating granulomas and forms in various tissues of the body.
Spleen involved in 50-80%.
Splenomegaly is usually only sign.
Aggregates of granulomatous splenic tissue in some patients may appear on CT as numerous, discrete 1-2cm hypodense nodules.
Rarely, can cause massive splenomegaly and rupture.
Gastric antrum is most common site in GI tract

Question 12

Peliosis (5)

Answer 12

Rare, characterized by multople blood filled cyst-like spaces in a solid organ.
Usually liver, can be in spleen (usually also with liver)
Unknown cause, but OCPs for women and anabolic steroids for men increase risk.
Other risk factors are AIDS, Renal transplant and Hodgkin Lymphoma.
Usually asymptomatic but can explode spontaneously.

Question 13

Splenic artery aneurysm (6)

Answer 13

Commonest visceral arterial aneurysm.
Pseudoaneurysm can occur in trauma or pancreatitis.
Highest incidence in women of childbearing age, who have had 2 or more pregnancies (4x more likely to get them, 3x more likely to rupture).
Usually sacular, in the mid to distal artery.
Usually fixed when 2-3cm.
Don’t biopsy thinking it’s a hypervascular pancreatic islet cell mass.

Question 14

Infarction (2)

Answer 14

Can occur due to many things, sickle cell is commonest in exams.
Wedge shaped infarct, peripheral, low attenuation defect.

Question 15

Splenic vein thrombosis (3)

Answer 15

Occurs as result of pancreatitis.
Can also occur in setting of diverticulitis or crohns.
Causes isolated gastric varices

Question 16

Splenic abscess (4)

Answer 16

Usually due to aerobic organism, classically salmonella.
Develops in setting of underlying splenic damage (trauma or sickle cell).
In immunocompromised, unusual organisms (fungi, TB, MAI, PCP) can occur and present as multiple microabscesses.
Occasionally, fungal infection may show bulls eye appearance on USS.

Question 17

Splenic infections (3)

Answer 17

Commonest radiologically detected is histoplasmosis (multiple round calcifications).
Splenic TB has similar appearance but is less common.
Brucellosis also causes calcified granulomas, usually solitary and larger (>2cm). May have low density center, encircled by calcification, giving Bull’s Eye appearance.

Question 18

Small spleen causes (4)

Answer 18

Sickle cell
Post radiation
Post thorotrast
Malabsorption syndromes (UC > Crohns)

Question 19

Big spleen causes (4)

Answer 19

Passive congestions (CHF, portal HTN, splenic vein thrombosis)
Lymphoma
Leukaemia
Gauchers

Question 20

Felty’s syndrome (2)

Answer 20

Abnormality of granulocytes.
Triad of Splenomegaly, RA, Neutripenia

Question 21

Splenic cysts - post traumatic (4)

Answer 21

Pseudocysts are most common splenic cystic lesion.
Can occur due to infarction, infection, haemorrhage or extension from pancreatic pseudocyst.
Called pseudo because they have no epithelial lining.
May have thick wall or prominent peripheral calcifications

Question 22

Epidermoid cysts (4)

Answer 22

Second commonest cystic lesion in spleen.
Congenital in origin.
Usually grow slowly and around 10cm at time of discovery.
Cause symptoms if large enough.
80% are solitary, 25% have peripheral calcifications.

Question 23

Hydatid or Echinococcal cysts (6)

Answer 23

3rd commonest cystic lesion in the spleen (commonest worldwide).
Caused by parasite echinoccus granulosis.
Hydatid cysts consist of spherical (mother) cyst which contains smaller daughter cysts.
Internal septations and debris are often referred to as hydatid sand.
Water lily sign - detachment of the endocyst membrane resulting in floating membranes within the pericysts (looks like water lily).
Was classically described on CXR in Pulmonary echinococcal disease

Question 24

Haemangioma (3)

Answer 24

Commonest benign neoplasm in spleen.
Smooth, well marginated with contrast uptake and delayed washout.
Classic peripheral nodular discontinuous enhancement seen in hepatic lesions may not occur, especially if <2cm.

Question 25

Lymphangioma (5)

Answer 25

Rare in spleen, but can occur.
Mostly in childhood.
Solitary or multiple.
Most in subcapsular region.
Diffuse lymphangionas may occur (lymphangiomatosis)

Question 26

Hamartomas (4)

Answer 26

Rare in spleen, can occur.
Usually incidental finding.
Most are hypodense or isodense, show moderate heterogenous enhancement.
Can be hyperdense if there is haemosiderin deposition.

Question 27

Littoral cell angioma (3)

Answer 27

Clinical hypersplenism is almost always present.
Usually presents as multiple small foci which are hypoattenuating on late portal phase.
MR shows haemosiderin (low T1 and T2)

Question 28

Angiosarcoma (6)

Answer 28

Commonest primary splenic malignancy.
Poor prognosis, aggressive.
CT: poorly defined area of heterogeneity or low density in an enlarged spleen.
Contain necrosis and get big enough to rupture (spontaneous rupture occurs in 30%).
Contrast enhancement is usually poor.
Can occur due to prior thorotrast exposure.

Question 29

Lymphoma (spleen) (4)

Answer 29

Commonest malignant tumour of spleen, usually seen as manifestation of systemic disease.
Splenomegaly is commonest finding, may be only finding in low grade disease.
Hodgkins and Non-hodgkin types can involve spleen. Hodgkins and high grade lymphomas can show discrete nodule sof tumour.
Low density on CT, T1 dark and PET hot.

Question 30

Metastatic disease to spleen (3)

Answer 30

Mets to spleen are rare.
Occurs due to common things (breast, lung, melanoma).
Melanoma is commonest primary neoplasm to met to spleen.