Clinical History
A 60-year-old man presented with left upper abdominal tenderness after a fall. His past medical history included cerebral infarctions and a splenic mass identified on prior CT examination, of uncertain aetiology. Laboratory tests were normal at presentation. However, a continuous decrease in his haematocrit over the next two days prompted exploratory laparotomy.
Imaging Findings
CT examination three years prior to the current presentation revealed an incidental, well-circumscribed, hypodense splenic mass (35 Hounsfield units).
MR examination was performed one year prior to the current presentation. T1-weighted out-of-phase (image 2a) and in-phase (image 2b) images demonstrated an isointense splenic mass which had enlarged since the prior CT examination. The mass was slightly hypointense compared with the adjacent splenic parenchyma on T2-weighted images (image 2c). There was relative hypoenhancement of the mass compared with normal parenchyma on early arterial-phase T1-weighted gradient recalled-echo images after IV gadolinium administration (image 2d), and near isointensity on late-phase images (image 2e).
CT examination with IV contrast agent at the time of current presentation shows a larger splenic mass containing high attenuation areas representing blood. A hypodense area extending to the periphery represents disruption of the mass. There is also high density perisplenic fluid.
Discussion
Inflammatory pseudotumour (IPT) of spleen is a rare, benign entity of uncertain aetiology and pathogenesis [1]. Like IPTs occurring in other locations in the body, it is histologically characterised by mixed inflammatory infiltrates and a smaller component of disorganised spindle cells [2]. The majority of cases of hepatic and splenic IPTs have been found to be positive for Epstein-Barr virus [3].
IPTs of spleen usually occur in adults, although a few cases have been reported in children. These are often discovered incidentally. The signs and symptoms are non-specific when present and include pain, fever, anaemia, splenomegaly, and complications of splenomegaly including thrombocytopenia [1].
Imaging findings include a well-circumscribed, solitary, splenic mass. Splenomegaly with left upper quadrant calcifications may be seen on plain radiographs. The mass is usually hypoechoic on sonography and may show acoustic shadowing from calcifications. CT examination reveals a hypodense splenic mass with or without calcifications and may demonstrate heterogeneous enhancement with intravenous contrast. Relative to the normal splenic parenchyma, the lesion is typically isointense on T1-weighted MR imaging and has variable signal intensity on T2-weighted imaging depending on tissue composition. A central area of low T2 signal intensity, consistent with scar, is strongly suggestive of the diagnosis. Enhancement patterns with IV gadolinium are variable and include early peripheral arterial to delayed persistent enhancement. On administration of MR contrast agents which accumulate in the reticuloendothelial system (RES), the lesion appears hyperintense on T2-weighted images, as it does not contain RES cells [1].
Inflammatory pseudotumour of the spleen is considered a benign disease process. No cases have been reported with a haemorrhagic presentation to our knowledge. Since imaging alone cannot be used to establish the diagnosis with certainty, percutaneous biopsy and/or splenectomy is necessary for definitive diagnosis.
Differential Diagnosis List
Ruptured inflammatory pseudotumour of spleen following blunt trauma.
Hamartoma
Haemangioma
Lymphoma
Final Diagnosis
Ruptured inflammatory pseudotumour of spleen following blunt trauma.
