Splenomegaly and Hypersplenism

 Congestive

– Right heart failure, portal hypertension, sickle cell disease (in acute setting), and splenic vein thrombosis


image Hematologic
– Polycythemia vera, myelofibrosis, and hemoglobinopathies

image Inflammatory/infectious
– Mononucleosis and HIV/AIDS most common infections to result in splenomegaly

– Sarcoid may result in mild splenomegaly with multiple small hypodensities in liver and spleen

image Space-occupying lesions
– Space-occupying masses in spleen do not commonly cause splenomegaly and are more likely to replace normal splenic tissue

– Cysts, lymphoma, metastases, and primary splenic tumors may very rarely cause splenomegaly

image Storage and infiltrative disorders
– Primary or secondary hemochromatosis, amyloidosis, and glycogen storage diseases





CLINICAL ISSUES




• Complications include splenic rupture and hypersplenism
image Hypersplenism: Hyperfunctioning spleen removes normal RBC, WBC, and platelets from circulation

image
(Left) Frontal radiograph demonstrates “fullness” in the left upper quadrant. The inferior edge image of an enlarged spleen is evident.


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(Right) Coronal T2 MR demonstrates a markedly enlarged spleen in a patient with myelodysplastic syndrome. The most common causes of massive splenomegaly are cirrhosis/portal hypertension, lymphoma, chronic myelogenous leukemia, extramedullary hematopoiesis, myelofibrosis, and Gaucher disease.

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(Left) Axial CECT shows a small, cirrhotic liver with widened fissures and signs of portal hypertension, including splenomegaly and varices image. In most patients with splenomegaly, there are clues as to the underlying cause on the imaging study, as in this case.


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(Right) Coronal CECT in an asymptomatic patient demonstrates a mildly enlarged spleen with multiple ill-defined hypodense nodules in a patient with known sarcoidosis. Lymphoma and metastatic disease could have a very similar appearance.


TERMINOLOGY


Abbreviations




• Splenomegaly (SMG)

• Hypersplenism (HS)


Definitions




• SMG: Splenic enlargement caused by a number of different underlying congestive, hematologic, inflammatory/infectious, neoplastic, or infiltrative disorders

• Hypersplenism: Syndrome consisting of splenomegaly and pancytopenia in which bone marrow is either normal or hyperreactive


IMAGING


General Features




• Best diagnostic clue
image ↑ volume of spleen with convex medial border

• Size
image No consensus on absolute size thresholds for SMG: Different sources suggest different measurements

image Normal spleen is ≤ 13 cm in length
– Width and breadth are usually ≤ 6 and 8 cm, respectively

image Splenic index: Normally 120-480 cm³ (product of length, breadth, and width of spleen)

image Splenic weight: Splenic index × 0.55
– Normal weight: 100-250 g

image SMG: Anteroposterior (AP) diameter > 2/3 distance of AP diameter of abdominal cavity

• Morphology
image SMG is often associated with abnormal contour of spleen, including rounding of poles and convexity of medial border


Radiographic Findings




• Radiography
image Normal-sized spleen usually not visualized

image SMG: Splenic tip below 12th rib

image Marked SMG may displace stomach medially

image Displacement of splenic flexure of colon (splenic flexure usually anteromedial to spleen)

image Calcification within or adjacent to spleen


CT Findings




• SMG is usually due to 1 of 5 general etiologies

• Congestive
image Right heart failure: Cardiomegaly with distension of hepatic veins/IVC and passive hepatic congestion

image Portal hypertension: Splenomegaly with varices, nodular shrunken liver, ascites, and other signs of portal hypertension

image Splenic or portal vein occlusion or thrombosis (often due to pancreatitis or pancreatic tumors)

image Sickle cell disease
– Acute phase: Diffusely decreased splenic density with splenomegaly

– Chronic phase: Development of small autoinfarcted, calcified spleen

• Hematologic
image Polycythemia vera

image Leukemia

image Myelofibrosis: SMG due to extramedullary hematopoiesis
– May be associated with other signs of extramedullary hematopoiesis (such as paraspinal soft tissue masses)

image Hemoglobinopathies: May cause splenomegaly (thalassemia) or small, infarcted spleen (sickle cell [SC])

image Acute splenic infarction: Global or wedge-shaped hypoenhancement of splenic parenchyma

• Inflammatory/infectious
image Mononucleosis

image Hepatitis: Splenomegaly due to viremia or cirrhosis with portal hypertension

image AIDS: SMG may reflect chronic viremia, opportunistic infection, or lymphoma

image IV drug abuse: SMG due to chronic low-level sepsis

image Tuberculosis, histoplasmosis: Multifocal low-density granulomas acutely that heal as calcified foci

image Sarcoidosis: Often associated with innumerable small hypodense splenic granulomas, ± upper abdominal lymphadenopathy, ± hepatomegaly with similar hypodense hepatic granulomas

image Collagen vascular or autoimmune diseases
– Rheumatoid arthritis, scleroderma, etc.

Nov 16, 2016 | Posted by in GASTROINTESTINAL IMAGING | Comments Off on Splenomegaly and Hypersplenism

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