Splenic infarctions stem from an embolic phenomenon
as well as from thrombosis of the splenic artery, splenic vein,
and their branches. They are one of the most common causes of focal
splenic lesions seen on cross-sectional images. In approximately
50% of cases they are multiple.
Focal splenic infarction may affect the overlying visceral peritoneum
resulting in acute left upper quadrant pain particularly on respiration
and movement.
Causes of splenic
infarction :
*Sickle cell anaemia.
*Leukaemia.
*Bacterial endocardites.
*Septic emboli.
*Systemic lupus erythematosus.
*Pancreatitis.
*Trauma.
*Left upper quadrant surgery.
*Vasculitis - polyarteritis nodosa.
*Myelofibrosis.
*Polycythaemia rubra vera.
*Mitral valve disease.
*Acute myocardial infarction - emboli.
*Hepatic arterial catheter placement, hepatic chemoembolisation.
*Local spread - gastric carcinome.
*Myeloid leukaemia - subendothelial infiltration.
*Granulomatous splenic infections : tuberculoses and histoplasmosis.
Ultrasonography
:
Initially the area of infarction is hypoechoic
and usually wedge-shaped, solitary and extending to the
periphery of the spleen. The lesion may decrease in time, and
gradually fibrose, becoming hyperechoic.
It demonstrates a lack of Doppler perfusion compared with the
normal splenic tissue. In rare cases of total splenic infarction,
due to occlusion of the proximal main splenic artery, grey-scale
sonographic appearances may be normal in the early stages. However,
as with focal infarcts, an alteration in splenic echogenicity
and echotexture can be a due to an underlying infarct. the lack
of color Doppler flow may assist in the diagnosis.
Occasionally infarcts may become infected or may hemorrhage. Sonography
can successfully document such complications and is used to monitor
their resolution serially.
In patients with multiple infarcts, such as those with sickle-cell
disease, the spleen may become scarred, giving rise to a patchy,
heterogeneous texture.
Differential :
Spleen infarcts may mimic :
*Lymphoma.
*Splenic lymphangiomatosis.
*Septic emboli - multiple small abscesses.
*Metastases. * haemangiomas.
*Splenic cysts - pseudocysts, epidermoid and hydatid cysts.
*Abscesses.
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