The Spleen



10.1055/b-0034-87864

The Spleen


The spleen is a wedge-shaped organ that is convex supero-laterally and concave inferomedially with a vascular hilum. It can be affected either by primary pathologic process or by multiorgan or systemic disease. Its histology varies with age, with little white pulp in the neonate, which increases with age.





























Table 2.22 Normal imaging

Diagnosis


Findings


Comments


US


Homogeneous, slightly hyperechoic than normal kidney.


With high-frequency transducers, a granular pattern can be seen in children aged 1 to 5 y.


CT


Unenhanced CT: Homogeneous. With contrast, irregular, bizarre patterns of enhancement that disappear in portal phase (> 70 s).



MR


Neonate: Hypointense on T2 and hyperintense (to liver) on T1. From 1 year of age, adult pattern: hyperintense on T2 and hypointense on T1. Irregular pattern of enhancement.



Nuclear medicine (NM)


99mTc-labeled heat-damaged red cells are only taken up by the spleen.


Useful if a normal spleen is not detected by other imaging methods.





































Table 2.23 Changes in position and shape

Diagnosis


Findings


Comments


Notches, clefts, and lobulations


Lobules are located near the hilum or extending anterior to the upper pole of the kidney. Clefts are sharp, located in the superior border, and sometimes 2–3 cm deep.


Normal in fetal period, usually disappear, but may be present into adult life.


Positional anomalies


Fig. 2.39


Situs inversus.


Wandering spleen: migration from its original position to a more caudal location because of laxity or lack of ligament fixation.


Wandering spleen is more common in females. It usually presents as an abdominal mass or as an acute abdomen due to torsion of the vascular pedicle with possible infarction.


Accessory spleen (s)


Fig. 2.40


Common anomaly (> 30%). Usually < 15 mm and located near the hilum, but can be multiple and in other locations. Same pattern that normal spleen.


Clinically insignificant. Increase in size after splenectomy.


Polysplenia syndrome (levoisomerism)


Multiple discrete spleens, right- or left-sided (at the same side of the stomach). Cardiac anomalies. Liver centrally located. No intrahepatic IVC, with azygous continuation. Mirror location of GI organs.


Wide range of abdominal anomalies. Most patients have severe cardiac anomalies, but 5%–10% reach adulthood without symptoms. More frequent in females.


Asplenia syndrome (dextro-isomerism)


Fig. 2.41


Absence of spleen. Severe congenital heart disease. Liver and gallbladder in midline. IVC and aorta lie on the same side of column. Short pancreas. Midgut malrotation.


Most die in the first year. Male predominance.


Vascular shunts


Splenogonadal, splenorenal, splenohepatic.


Fig. 2.39 Situs inversus. Transverse US through epigastrium shows a left-located liver and gallbladder and a right-sided air-distended stomach (ST).
Fig. 2.40 Accessory spleen. Longitudinal US shows an isoechoic splenic parenchyma nodule (arrowhead) near the splenic hilum, representing accessory tissue.
Fig. 2.41 Asplenia syndrome. Plain film in a neonate showing the central position of liver.








































Table 2.24 Splenomegaly

Diagnosis


Findings


Comments


Infection, sepsis


Usually homogeneous splenomegaly.


Many causative organisms: Bacterial, viral, protozoal, fungal. Some of them produce isolated splenomegaly: Ebstein-Barr virus, malaria, histoplasma, mycobacterium.


Portal hypertension


Often due to extrahepatic portal vein thrombosis:


Doppler US with absent or reversed flow or with cavernomatous transformation. Splenomegaly with heterogeneous hepatomegaly with lobulated margins.


Common causes: liver disease, umbilical vein catheterization, tumor, dehydration, omphalitis, hypercoagulability states.


Malignant diseases: leukemia, lymphoma, Langerhans cell histiocytosis, metastases


Either homogeneous splenomegaly or single or multiple masses can be present.


Look for other manifestations of disease.


Metabolic disease: Gaucher, Niemann-Pick, mucopolysaccharidosis, tyrosinosis


Homogeneous splenomegaly. Usually correlates with severity of disease.


Abnormal products of metabolism are stored in spleen parenchyma.


Hemolytic anemia



Due to sequestration of abnormal red cells.


Extracorporeal membrane oxygenation



Due to increased number of damaged red cells.


Right heart failure



Due to congestion.





























Table 2.25 The small spleen

Diagnosis


Findings


Comments


Normal variant



Congenital hypoplasia.


Infarction (late phase)


Small spleen, sometimes with capsular calcification.


Secondary to emboli, torsion, portal hypertension, Gaucher disease.


Autosplenectomy



In sickle cell disease, thalassemia.


Celiac disease



In late phases of disease.

































Table 2.26 Focal anomalies, solitary

Diagnosis


Findings


Comments


Cyst: serous, epidermoid, dermoid, echinococcal, pseudocyst (trauma, infarct)


Fig. 2.42a, b, p. 170


Usually unilocular, with clear and homogeneous fluid.


Echinococcal and pseudocyst may calcify Echogenicity (US), density (CT), and signal intensity (MR) may vary due to composition of fluid.


Hemangioma


Septate, subcapsular cystic lesions. No contrast enhancement.


Solitary or multiple.


Lymphangioma


May appear cystic, solid, or a combination.


May cause Kasabach-Merritt syndrome if large.


Hamartoma


Solid and avascular lesions, heterogeneous.


Most common primary neoplasm.


Solitary focus of a typically multifocal disease (see Table 2.27)



Fig. 2.42a, b Epidermoid cyst. (a) Longitudinal US depicts a splenic cystic mass (C) with low-level echoes. (b) Contrast-enhanced CT of the same cyst.




























Table 2.27 Focal anomalies, multiple

Diagnosis


Findings


Comments


Abscess


Fig. 2.43


Fig. 2.44


Fig. 2.45


Centrally located, rounded, or irregular in shape with central fluid/necrosis. Avascular. Fungal abscess are small lesions (few millimeters).


Seen in immunosuppressed population (on chemo-therapy, acquired immunodeficiency syndrome [AIDS])


Trauma


Lacerations, rupture, intrasplenic and subcapsular hematomas.


Sometimes, minor trauma can affect spleen.


Lymphoproliferative disorders, Langerhans cell histiocytosis, metastases


Fig. 2.46


Fig. 2.47


Multiple focal masses. Lymphoma can invade the capsule. Lymphadenopathy in hilum and retroperitoneum can be seen.


Look for other manifestations of disease.


Gaucher, Niemann-Pick disorders


Multiple nodules. On MRI, T1 signal is lower than for normal spleen.


Fig. 2.43 Salmonella abscess. Longitudinal US in a 17-year-old boy with Salmonella infection and fever. A solitary abscess (between arrowheads) was found in splenic parenchyma.
Fig. 2.44 Candida abscess. In a neutropenic 5-year-old girl treated for neuroblastoma, transverse US shows multiple fungal abscess cavities.
Fig. 2.45 Pyogenic abscess. Contrast-enhanced CT in a 15-year-old boy with a pyogenic abscess treated with percutaneous drainage.
Fig. 2.46 Non-Hodgkin lymphoma. Longitudinal US shows multiple heterogeneous solid nodules.
Fig. 2.47 Metastasis. Contrast-enhanced CT shows a discrete splenic mass (between arrowheads) representing metastasis from renal sarcoma.




























Table 2.28 Diffuse anomalies

Diagnosis


Findings


Comments


Lymphoproliferative disorders, Langerhans cell histiocytosis, metastases



Depending on underlying disease.


Infarction (early phase)


Hypoattenuating (CT) spleen, with only capsular enhancement.


Patients with sickle cell disease are prone to infarction.


Iron deposition disease


MRI: low signal on T1 and T2.



Hemangioma, hemangioendothelioma



May affect the entire spleen.





























Table 2.29 Splenic calcifications

Diagnosis


Findings


Comments


Granulomatous diseases


Multiple tiny foci of calcium.


Histoplasma, cat-scratch, chronic granulomatous disease.


Infarction


Isolated peripheral, associated with scarring.



Cysts, hematoma, abscesses


Peripheral calcification.



AIDS


Arterial splenic calcifications.


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Jul 12, 2020 | Posted by in PEDIATRIC IMAGING | Comments Off on The Spleen
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