SPLENIC CYSTS HAEMANGIOMA ABSCESSES
Category: Diagnostic Radiology
Abstract : BENIGN SPLENIC CONDITIONS Many benign focal lesions which occur in the
spleen are of similar nature and ultrasound appearances to those in the liver.
Focal lesions are less common in the spleen, however. Cysts Splenic
cysts have a relatively low incidence, but are nevertheless the most common
benign mass found in the spleen. They demonstrate the usual acoustic
characteristic
BENIGN SPLENIC CONDITIONS
Many benign focal lesions which occur in the
spleen are of similar nature and ultrasound appearances to those in the liver.
Focal lesions are less common in the spleen, however.
Cysts
Splenic
cysts have a relatively low incidence, but are nevertheless the most common
benign mass found in the spleen.
They demonstrate the usual acoustic
characteristics of well-defined capsule, no internal echoes and posterior
enhancement. Splenic cysts may occasionally be associated with adult polycystic
disease. Other causes of cystic lesions in the spleen include post-traumatic
cysts (liquefied haematoma), hydatid cysts (Echinococcus granulosus parasite) or
cystic metastases (for example from primary ovarian carcinoma, which may contain
mucin). As with hepatic cysts, haemorrhage may occur, causing LUQ pain. Large
cysts may be resected, in order to avoid rupture.
Haemangioma
The
benign haemangioma occurs rarely in the spleen. As in the liver, it is usually
hyperechoic and well-defined, though may, rarely, contain cystic areas. Like the
hepatic haemangioma, they may pose a diagnostic dilemma as characterization is
difficult with ultrasound alone. In cases with a low clinical suspicion of
malignancy, such lesions may be followed up with ultrasound, and tend to remain
stable in size. Less commonly, haemangiomas may also be
multiple.
Abscess
Splenic abscesses are relatively uncommon compared
with their incidence in the liver. They usually result from blood-borne
bacterial infection, but can also be due to amoebic infection, post-traumatic or
fungal infection. Patients with splenomegaly resulting from typhoid fever,
malaria and sickle cell disease are particularly predisposed to the formation of
multiple pyogenic abscesses in the spleen.
Increasingly splenic abscesses
are associated with immunosuppressed patients, patients with AIDS and those on
high-dose chemotherapy. Such patients become susceptible to invasive fungal
infections which can cause multifocal microabscesses in the liver and spleen.
Patients present, as might be expected, with LUQ pain and fever.
The
ultrasound appearances are similar to liver abscesses; they may be single or
multiple, hyperechoic and homogeneous in the early stages, progressing to
complex, fluid-filled structures with increased through-transmission. Splenic
abscesses are frequently hypoechoic and it may not be possible to differentiate
abscess from lymphoma or metastases on ultrasound appearances alone. This
applies both in cases of large solitary abscesses and in multifocal
micro-abscesses. They may also contain gas, posing difficulties for diagnosis as
the area may be mistaken for overlying bowel. As with liver abscesses,
percutaneous drainage with antibiotic therapy is the management of choice for
solitary abscesses.
Calcification
Calcification may occur in the wall
of old, inactive abscess cavities, forming granulomatous deposits. Other
infective processes, particularly in association with AIDS, may cause multiple
small calcific foci throughout the spleen and liver.
Calcification is
also associated with posttraumatic injury and may be seen around the wall of an
old, resolving post-traumatic haematoma. Conditions which predispose to the
deposition of calcium in tissues, such as renal failure requiring dialysis, are
also a source of splenic calcification.
Haemolytic anaemia
Increased
red blood cell destruction, or haemolysis, occurs under two circumstances: when
there is an abnormality of the red cells, as in sickle cell anaemia,
thalassaemia or hereditary spherocytosis, or when a destructive process is at
work, such as infection or autoimmune conditions. Fragile red cells are
destroyed by the spleen, which becomes enlarged.
Sickle-cell anaemia is
most prevalent in the black American and African populations. Progression of the
disease leads to repeated infarcts in various organs, including the spleen,
which may eventually become shrunken and fibrosed. Patients have
(non-obstructive) jaundice because the increased destruction of red blood cells
(RBCs) releases excessive amounts of bilirubin into the blood.
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