Gastrointestinal: Spleen Flashcards
What creates the tiger stripe appearance of the spleen on arterial phase imaging?
Different perfusion timing between the red and white pulp of the spleen
Note: The red pulp is filled with blood and enhances during the arterial phase.
Why is the spleen particularly susceptible to infarction?
It has only one major arterial supply (the splenic artery) without any significant collaterals
Note: The splenic artery is basically and end vessel.
Most splenic masses are benign, but what are the most common primary malignant splenic masses?
- Lymphoma
- Angiosarcoma
How does the spleen appear on MRI?
- T1 dark (relative to liver)
- T2 bright (relative to liver)
- Restricts diffusion
Note: The spleen is basically a big watery lymph node (it restricts diffusion like a lymph node).
What is a possible reason for recurrence of hemolytic anemia s/p splenectomy?
Hypertrophy of a splenule
Note: Splenules should also be removed during a therapeutic splenectomy.
Wandering spleen
A normal spleen that moves to unusual places due to laxity of the peritoneal ligaments
Note: These pts are at a higher risk for splenic torsion and infarction.
Wandering spleen is associated with…
Abnormalities of intestinal rotation
Note: Also has a higher risk of splenic torsion and infarction.
What is the most common solid organ injured during trauma?
The spleen
How much blood does the spleen hold?
Approximately 1 liter
Why is a trauma scan done in the portal vinous phase?
To evaluate for splenic injury (avoids the tiger striped appearance in arterial phases)
What study can be used to determine that peritoneal nodules are splenules/splenosis and not metastases?
Sulfur colloid scan
Note: Heat-damaged RBC scan could also be used.
Splenosis
The development of multiple splenules due to prior splenic trauma
Note: These are usually in the upper abdomen, but can be anywhere (including the lungs if the diaphragm is traumatically disrupted at the time of spleen injury).
Numerous rounded soft tissue nodules in the peritoneal cavity of a pt who doesn’t have a spleen…
Think splenosis due to prior splenic trauma (spleen is often surgically removed if it is injured)
Imaging findings of the spleen in sarcoidosis
- Splenomegaly (50-80%)
- Numerous discrete hypodense splenic nodules representing granulomatous splenic tissue (more rare)
- Massive splenomegaly with rupture (rare)
What is the most common GI tract location to be involved in sarcoidosis?
The gastric antrum
Splenomegaly with sideritic nodules (Gamna Candy bodies)
Note: These are small T2 dark foci of hemorrhage in the splenic parenchyma, usually associated with portal hypertension.
What is the most sensitive MRI sequence for splenic sideritic nodules (Gamna Candy bodies)?
Gradient echo
Peliosis (multiple blood-filled cyst-like spaces in solid organs, usually the liver and spleen)
Peliosis most commonly occurs in what pt populations?
- Women on oral contraceptives
- Men on anabolic steroids
- AIDS pts
- Renal transplant pts
- Pts with Hodgkins lymphoma
What is the most common visceral arterial aneurysm?
Splenic artery aneurysm
At what point is a splenic artery aneurysm usually treated?
When it reaches 2-3 cm large
_____ are at a 4x increased risk of splenic artery aneurysms
Woman of childbearing age who have had 2 or more pregnancies
Common causes of splenic vein thrombosis
- Pancreatitis
- Diverticulitis
- Crohn’s disease
______ can lead to isolated gastric varices
Splenic vein thrombosis
What is a common cause of spontaneous splenic infarction?
Sickle cell disease
What is the most common radiographically-detected splenic infection?
Histoplasmosis (which appears as multiple round calcifications)
Note: TB can also look like this, but is much less common in the US.
Multiple round splenic calcifications, consider histoplasmosis or tuberculosis infection
“Bulls-eye” calcification in the spleen, consistent with chronic Brucellosis infection
What splenic infection classically develops after splenic damage (e.g. trauma or sickle cell)?
Salmonella
Common causes of a small spleen
- Sickle cell disease
- Radiation changes
- Post thorotrast
- Malabsorption syndromes (ulcerative colitis > Crohns)
Common causes of splenomegaly
- Passive congestion (e.g. heart failure, portal hypertension, splenic vein thrombosis)
- Leukemia/lymphoma
- Gauchers
- Felty’s syndrome
Felty’s syndrome triad
- Splenomegaly
- Rheumatoid arthritis
- Neutropenia
Note: This is an abnormality of granulocytes.
What is the most common cystic lesion in the spleen?
Post traumatic pseudocysts (followed by epidermoid cysts)
Note: These do not have an epithelial lining and so are not true cysts.
Most likely diagnosis
Post traumatic splenic pseudocyst (followed by epidermoid cyst)
Splenic hydatid cyst
Note: Daughter cysts.
What is the most common benign neoplasm in the spleen?
Hemangioma
Splenic hemangioma
Note: Peripheral nodular discontinuous enhancement (this is not always seen in the spleen, especially when small).
Pediatric pt
Splenic cystic lymphangioma
Differential for benign masses of the spleen
- Post traumatic pseudocyst
- Epidermoid cyst
- Hydatid (Echinococcal) cyst
- Hemangioma
- Lymphangioma
- Hamartoma
- Littoral cell angioma
Differential for malignant masses of the spleen
- Lymphoma (by far the most common)
- Angiosarcoma (rare)
- Metastatic disease (rare)
Why does a littoral cell angioma appear hypointense on T1 and T2?
Hemosiderin
Splenic angiosarcoma
Note: Heterogeneously hypodense infiltrating mass in an enlarged spleen.
What is the major complication of splenic angiosarcoma?
Splenic rupture (spontaneous rupture occurs in 30% of cases)
What is the most common imaging finding of splenic lymphoma?
Splenomegaly (often the only finding in low grade disease)
Note: Hodgkins and high-grade lymphomas often show discrete hypodense nodules.
What is the most common primary neoplasm to metastasize to the spleen?
Melanoma
Note: Splenic mets are rare.
