the spleen lecture slides

what is the largest lymphoid organ in the body?

spleen

The spleen is….

• intraperitoneal

• retroperitoneal

• neither

intraperitoneal

The outer layer of capsule is peritoneum. It covers the entire organ except…

the hilum

What layer is fibroelastic and smooth muscle fiber capsule that surrounds the entire organ (allows it to expand and contract)?

middle layer

what layer of the capsule projects into the organ, forming partitions in the pulp?

inner layer

What is the spleen’s echogenicity compared to healthy liver tissue?

homogeneous and only slightly more echogenic

What is the spleen’s echo structure compared to kidney tissue?

hyperechoic

What is the normal spleen length?

<12 cm

what is the normal spleen width?

<7 cm

what is the normal spleen thickness?

<5 cm

True/False: The left lobe of the liver does not touch the spleen normally, if enlarged it may, as well as in 3rd trimester of pregnancy.

true

What are strands of connective tissue that project from the splenic capsule and divide the spleen into several compartments?

Trabeculae

what is cords of splenic tissue called?

cords of Billroth

What is white pulp (15%)?

clusters of lymphatic tissue called Malpighian corpuscles that form a sheath around the splenic artery and produce lymphocytes and is a major site for immunologic activity

What is is a major site for immunologic activity?

white pulp

What is the principle site of filtration, and performs major functions related to blood cells (These include the removal of macrophages of ruptured, worn out, or defective blood cells)?

red pulp

What are the functions of the spleen?

1.Blood filtration
2. Blood production: Glucocytes and plasma cells are produced
3. Blood destruction
4. Blood storage: Main storehouse of the blood
5. Storage of iron

Hemoglobin from the red blood cells is passed to where for storage and bile production?

the liver

What is found within this concavity and acts as an entry and exit route for the arterial, venous, and lymphatic vessels and nerves?

the splenic hilum

What are medial and anterior to splenic hilum?

Stomach fundus and lesser sac

What is inferior and medial to spleen?

Left kidney

What is anterior to UP of left kidney?

Pancreatic tail

Where is the spleen located?

The spleen is located in the left hypogastric quadrant of the abdomen and is fixed in its intra-peritoneal position beneath the 9th to 11th intercostal spaces by the spleno-renal, spleno-colic, spleno-gastric, and phrenico-splenic ligaments.

True/False: The splenic artery initially divides into two major branches before separating into several minor arterioles within the spleen. It is not important for the sonographer to remember that because there are no adequate anastomoses between arteries in the spleen, the organ is susceptible to infarction.

false, because it is important for the sonographer to remember this

What is the spleen susceptible to?

infarction

Blood from the arterioles flows into the venous sinusoids and then exits through
branches of the…

splenic vein

Where does the splenic vein originate?

at the splenic hilum

What courses posteroinferior to the pancreas body and tail?

splenic vein

Splenic vein joins with IMV, then SMV to form what?

MPV

What does the splenic vein drain?

stomach, spleen, and pancreas

What is the largest branch of the celiac axis?

splenic artery

What courses superior and anterior to the body and proximal tail of the pancreas?

splenic artery

What is low resistance and supplies the spleen, pancreas and fundus of the stomach?

splenic artery

What is considered the most tortuous artery in human body?

splenic artery

What are indications for US for the spleen?

1. Left upper quadrant pain 2.Splenomegaly
3. Anemia 4.Traumatic disorders
5. Congenital anomalies 6.Focal defects
7.Hematogenic and lymphogenic disorders
8.Liver disease 9. Metastases

What probe is best to use for examining the spleen?

2.5MHz to 6.5MHz adult probe

4MHz to 8MHz pediatric probe

Describe the spleen on US?

-Homogeneous texture
- Echogenicity the same as or slightly below the normal liver echogenicity
- Smooth border at diaphragm
- Intercostal coronal view used to obtain spleen length
- Average length 11-13cm; usually decreases in size with age
- Usually 2/3 size of the liver
- Deep inspiration usually necessary to evaluate the entire organ

What is a relatively common anatomic variant?

accessory spleen (Splenule)

Most accessory spleens are small and measure between…

1.5 and 2.0 cm

True/False: Approximately 75% of accessory spleens are found near to the normal spleen within the splenic hilum or gastrosplenicligament omentum, rare locations for an accessory spleen include the pelvis or scrotum.

true

True/False: Following splenectomy, an accessory spleen may assume the function and size of the removed organ.

true

An accessory spleen or splenule is _______ to spleen

• hypoechoic

• Isoechoic

• hyperechoic

• heterogeneous

Isoechoic

What does the following describe?

-Absence of the spleen

-Very rare

-Usually occurs in cases of multiple congenital anomalies such as right sided aorta, midline liver, horseshoe kidneys and adrenal glands

-Congenital heart defects are common

Asplenia

What describes the following?

-Formation of multiple spleens

-Associated with biliary atresia, absence of the gallbladder, interrupted IVC, intestinal malrotation

-Congenital heart defects are common

Polysplenia

What is the disruption in the development of normal asymmetric arrangement of abdominal organs and vessels; Generic term meaning mis-arrangement of abdominal structures?

Heterotaxia or situs ambiguous

What can occur if the supporting ligaments are dysfunctional or lax?

Splenic ptosis aka wandering spleen

What does the following describe?

•Weak splenic ligaments lead to the organ migrating to unusual locations

•Mistaken for a mass

•Due to the abnormal location, it may undergo torsion resulting in pain .It may also undergo infarction

Splenic ptosis aka wandering spleen

The preferred treatment for wandering spleen is ____________ in which a surgeon repositions the spleen in the left upper quadrant in order to prevent torsion of splenic vessels and preserve splenic function.

splenopexy

What is the measurement for enlarged spleen (splenomegaly)?

>13cm in length

What is the most common splenic abnormality observed sonographically?

enlargement (splenomegaly)

What is the most common cause of splenomegaly?

Portal hypertension due to cirrhosis is most common cause in adults

What is the most common malignant disease that affects the spleen?

lymphoma (Hodgkin disease and non-Hodgkin)

What is a blood disorder resulting from uncontrolled RBC production causing hyperviscosity and hypercoagulation; May be the cause of splenomegaly, Budd-Chiari syndrome, PV thrombosis and splenic infarcts?

Polycythemia Vera

The spleen suddenly enlarges and is accompanied by a sharp decrease in ______.

hematocrit

With splenomegaly: when enlarges, it extends

anteriorly, medially and inferiorly

What does the following describe?

•Anechoic, well-defined walls, enhanced sound transmission

•Sharply demarcated wall, multilocular internal structure representing daughter cyst, mural calcifications

•Large cysts, dense, clearly defined walls May not have well-defined wall, mural calcifications Single or multiple simple cysts

splenic cysts

What are the different types of splenic cysts?

•Can be Congenital

•Can also be Acquired

• Echinococcal (hydatid)

•Epidermoid or epithelial

•Posttraumatic or postinflammatory pseudocysts

What does the following describe?

•True cysts lined by squamous epithelium

•Typically solitary, 10 cm

•Wall may be calcified and internal contents echogenic

Epidermoid or epithelial

What does the following describe?

•Polycystic kidney disease lymphangioma,

•extension of pancreatic pseudocyst

-Erode into spleen due to proximity

-May weaken vessels causing pseudoaneurysms and bleeding into pseudocyst

Posttraumatic or postinflammatory pseudocysts

What does the following describe?

•It is rare. May be associated with endocarditis, septicemia and trauma

•May see them status post splenectomy

•Symptoms include pain, dizziness, faintness,

•Lab Testing: decreased hematocrit, fever, increased WBC and possible septicemia

splenic abscess

What does the following describe?

•Sonographically: Complex fluid collection with internal echoes

•Irregular borders

•May see septations and pleural effusion

•Dirty shadowing from gas producing organisms

splenic abscess

What does the following describe?

•Areas of tissue death, blood supply is cut off

•Found in patients with leukemia, sickle cell anemia, pancreatitis, bacterial endocarditis

•Calcification is last change

splenic infarct

Focused assessment with Sonography for trauma (FAST) – used in ER to determine what?

if free fluid is in the peritoneal cavity

True/False: Fractured spleen may appear only as enlarging spleen with normal echogenicity; blood might be found in pelvis, flanks, Morrison pouch, lesser and greater sacs.

true

What is the condition of the capsule?

-intra-parenchymal or sub-capsular hematoma

-Subcapsular hematoma may appear as normal spleen, or hypoechoic, or echogenic mass adjacent to clearly defined capsule

capsule remains intact

What is the condition of the capsule?

-intraperitoneal or peri-splenic hematoma

-Fluid localized around spleen, but may spread within peritoneal cavity

-Pericapsular hematoma may efface smooth contour of splenic capsule

capsule ruptures

What can hematoma be due to?

•Trauma, coagulation disorder

•Ruptured spleen secondary to trauma or enlargement

US appearance of intraperitoneal blood depends on what?

age, amount, and physical state of the clot

What is it called when a patient with rupture or surgery, splenic cells may implant throughout peritoneal cavity resulting in an ectopic spleen? (is often asymptomatic and may mimic other pathologies)

posttraumatic splenosis

What are focal lesions that are resulting from previous infection; most common causes are histoplasmosis and tuberculosis?

Granulomas

Other calcifications in spleen can be associated with?

•Splenic artery or splenic artery aneurysms

•Pneumocystis carinii infection

•Splenic infarcts (as it evolves)

True/False: Rarely splenic hemangiomas may contain calcifications.

true

What is a very rare benign splenic tumor?

Primary neoplasms

What are the most common benign primary neoplasm of spleen?

Hemangiomas

What is a malignant tumor of the spleen?

Lymphoma

What does the following describe?

•Tumor of lymphatic nodes

•Commonly involves the spleen                      

•Elevated alkaline phosphatase values

•Solid hypoechoic well circumscribed areas or can be nearly isoechoic

•Marked splenomegaly due to tumor formation

•Areas of cystic degeneration within the tumors

Lymphoma

What are the four sonographic patterns of lymphoma in the spleen?

•Diffuse, marked splenomegaly, patchy inhomogeneity

•Multiple small hypoechoic lesions

•Multiple large lesions

•Bulky solid mass lesions

What is the most common type of lymphoma?

Hodgkin's disease

With lymphoma the sonographer should also evaluate for…

Evaluate the abdomen for lymphadenopathy; splenic and renal hilum areas, porta hepatis and para-aortic areas

metastases to the spleen seem relatively ________

• common

• uncommon

• neither

uncommon

What do METS most commonly occur in?

malignant melanoma

What may also occur with ovary, breast, lung, pancreas and stomach primaries, and Sonographically: hypoechoic is common, but it may vary?

Metastasis

What describes the following?

•Those may be single or multiple and are most commonly involving the distal portion of the artery.

•Peripheral calcification is common, and mural thrombus may be present

•Usually, calcified circle seen in LUQ on X-ray and this is suspected

•Sonographically: may appear as cystic mass, or if calcified a hyperechoic shadow foci in area of artery

splenic artery aneurysm

Size of splenic artery aneurysms can range from…..

2 to 9 cm, but usually it is smaller than 3 cm

What are two characteristics of patients who have AIDS?

•Moderate splenomegaly in 50-70% of patients

•Splenomegaly noted more in patients with sexually transmitted HIV than in those acquiring the disease through IV drug use