Axial T1 FS image showing large relatively thick walled fluid collection with debris and air pockets. Note the air fluid level anteriorly |
Sagittal T2 Wt image showing the abscess with airfluid level anteriorly- suggests pyogenic abscess. |
Axial DWI image showing mild restriction within the abscess.
|
·
The rarity of primary splenic abscesses is probably related to
splenic phagocytic immune functions.
·
A splenic abscess may be bacterial, fungal, or granulomatous.
·
In infants and children, splenic abscesses occur most frequently
in immunocompromised patients.
·
Abscesses may be single or multiple.
·
With fungal infections in an immunocompromised patient, abscesses
are typically multiple.
·
Pyogenic abscesses can be secondary to underlying sepsis or spread
by hematogenous seeding.
·
Amebic dysentery, otitis media, mastoiditis, peritonsillar
abscess, cutaneous infection, pneumonia, empyema, appendicitis, osteomyelitis,
and intravenous drug abuse are all risk factors.
·
Patients with hemoglobinopathies are also at risk for splenic
abscess formation secondary to infarction and necrosis as well as functional
asplenia.
·
Pyogenic abscesses manifest as ill-defined, hypoechoic lesions at
US. Debris and internal septations may be present. In rare cases, gas bubbles
may be seen.
·
If present,
intralesional gas is pathognomonic for pyogenic infection.
·
At CT, pyogenic abscesses typically manifest as single,
irregularly marginated lesions with low attenuation. Rim enhancement can be
seen on contrast enhanced scans.
·
Fungal abscesses are small lesions, typically only a few
millimeters in diameter.
·
The most common infecting organisms are Candida albicans,
Aspergillus fumigatus, and Cryptococcus neoformans.
·
M tuberculosis, M avium intracellulare, and P carinii infection
can have similar appearances.
·
Fungal abscesses have a variable appearance at US.
·
Typically, they manifest as rounded, hypoechoic lesions with a
central area of increased echogenicity, creating a “target” or “bull's-eye”
appearance. These findings correspond to fibrotic tissue surrounding a central
inflammatory core at histopathologic analysis.
·
The “wheel-in-a-wheel” appearance is seen when the central
hyperechoic portion becomes necrotic and hypoechoic.
·
Hepatosplenomegaly is usually associated with fungal abscesses. CT
typically demonstrates multiple small, low-attenuation lesions. The lesions may
be missed unless intravenously administered contrast material is used.
·
Reference:
A Pattern-oriented Approach to Splenic
Imaging in Infants and Children, November 1999 RadioGraphics, 19, 1465-1485.
No comments:
Post a Comment
Please leave your comments