CONGENITAL ABNORMALITIES OF THE SPLEEN

CONGENITAL ABNORMALITIES OF THE SPLEEN

Splenic agenesis is rare but is present in 5% of children with congenital heart disease. Polysplenia is a rare condition result ing from failure of splenic fusion. Splenunculi are single or multiple accessory spleens that are found in approximately 10–30% of the population. They are located near the hilum of the spleen in 50% of cases and are related to the splenic vessels, or behind the tail of the pan creas in 30%. The remainder are located in the mesocolon, greater omentum or the splenic ligaments. Their significance lies in the fact that failure to identify and remove these at the time of splenectomy may give rise to persistent disease . Hamartomas are rarely found in life and vary in size from 1 /uni00A0 cm in diameter to masses large enough to produce an abdominal swelling. One form is mainly lymphoid and resem bles the white pulp, whereas the other resembles the red pulp. Non-parasitic splenic cysts are rare. Splenic cysts are classified as primary cysts (true) or pseudocysts (secondary) on the basis of the presence or absence of lining epithelium. True cysts form from embryonal rests and include dermoid and mesenchymal inclusion cysts ( Figure 70.4 ). Rarely , the entire cysts of the spleen are very rare and are frequently classified as cystic haemangiomas, cystic lymphangiomas and epider - - moid and dermoid cysts. Splenectomy or partial splenectomy is usually considered for cysts larger than 5 /uni00A0 cm in diameter . These should be di ff erentiated from false or secondary cysts that may result from trauma and contain serous or haemor - of rhagic fluid. The walls of such degenerative cysts may be cal - - cified and therefore resemble the radiological appearances of a hydatid cyst ( Figure 70.6 ). The spleen is also a common site for pseudocyst development following a severe attack of pan - creatitis ( Figure 70.7 ). Pseudocysts can easily be diagnosed on scanning; intervention is normally required for symptomatic lesions that persist following a period of observation. - - - - -

Figure 70.4 Computed tomography scan showing multiple low-density areas in the spleen consistent with multiple benign splenic cysts. Figure 70.5 T2-weighted coronal magnetic resonance image showing a large, homogeneously hyperintense lesion (asterisk) in the region of the spleen displacing the left kidney inferiorly (arrow). Note that the normal splenic parenchyma is completely replaced by the cyst (courtesy of Dr Amit Kumar Sahu, New Delhi, India).

Figure 70.6 Axial contrast-enhanced computed tomography scan shows a well-de /f_i ned hypodense lesion (arrow) in the spleen with mild internal calci /f_i cation suggestive of splenic hydatid (arrowhead) (courtesy of Dr Amit Kumar Sahu, New Delhi, India). Figure 70.7 Computed tomography scan showing a large pseudocyst involving the spleen. There is displacement of the stomach medially and a trace of ascitic /f_l uid (arrowhead) is present above the liver.