Pediatric abdominal masses - PowerPoint Presentation

Slide1

Pediatric abdominal massesSlide2

1-

Abdominal masses are common in infants and children,

2-

and imaging plays an important role in their diagnosis and management.

3-

Plain radiographs provide clues to the location of the mass and the presence of calcifications.

4-

US is generally the most valuable procedure for the initial evaluation.

5-

US differentiates cystic from solid masses, indicates the organ of origin, and commonly suggests the diagnosis.

6-

CT or MR may be needed when the mass is large, poorly defined, or obscured by bowel gas.Slide3

1-

Pseudomasses may be caused on abdominal radiographs by a fluid-filled stomach, urinary bladder, or a loop of intestine.

2-

Structures outside the abdomen, such as large skin lesions, umbilical hernias, and

meningomyelocele

, can also mimic an abdominal mass.

3-

The most common abdominal masses in infants and children are enlarged kidneys caused by

hydronephrosis

or cystic renal disease

.Slide4

Renal and Adrenal Masses

Large Kidneys

1-

Unilateral enlargement of a kidney results from

hydronephrosis

,

multicystic

dysplastic kidney, renal vein thrombosis, or renal tumors .

2-

Bilateral renal enlargement can be seen with

hydronephrosis

, polycystic kidney disease, storage diseases, and

glomerulonephropathies

, including

nephrotic

syndrome.

3-

Bilateral renal enlargement caused by

neoplasms

is less common, although leukemia or lymphoma may infiltrate the renal parenchyma bilaterallySlide5
Slide6

Nephroblastomatosis

1

-Small islands of primitive

metanephric

blastema

, which are thought to be a precursor of

Wilms

tumor, commonly exist in the kidneys of the normal newborn infant.

2

- These primitive cells usually spontaneously regress by 4 months of age.

3- A diffuse and proliferative form of persistent renal

blastoma

is referred to as

nephroblastomatosis

.

The abnormal tissue can form as multiple discrete nodules within the renal parenchyma or may completely replace the renal cortex. -

Nephroblastomatosis

appears on CT or IV

pyelogram

as bilateral

lobulated

and enlarged kidneys with marked compression, stretching, and distortion of the

pelvicaliceal

structures Slide7

FIGURE

52.55

.

Nephroblastomatosis

. A. The kidneys are massively enlarged, with

lobulated

thickening of the parenchyma and stretching and compression of the collecting structures. B. T1WI in another patient shows multiple peripheral

Wilms

tumors (arrows) in a child with

nephroblastomatosis

.Slide8

On US, the kidneys are enlarged, lobular, and

echogenic

, or enlarged with diffuse

hypoechoic

thickening of the cortex. In such cases,

Wilms

tumor should be suspected.

Nephrogenic

rests are more likely to appear cortical, tend to be homogeneous, and are of low

echogenicity

on US, low attenuation on CT, and low signal intensity on T1WIs . Small, focal

nephrogenic

rests smaller than 1 cm are difficult to visualize by US and are better evaluated with contrast-enhanced CT or T1WISlide9

Wilms

tumor is the most common renal neoplasm of childhood (81). It arises from the primitive

metanephric

epithelium and demonstrates varied

histologies

, which are classified into favorable and unfavorable groups. The prognosis is dependent on tumor histology and

resectability

, with survival above 90% for tumors with favorable histology.

Wilms

tumor presents as a

nontender

, rapidly growing, unilateral abdominal mass in a young child. The mean age of presentation is 3 years. Bilateral tumors are found in 10% of

patientsâ

€”more commonly in children with associated congenital anomalies or

nephroblastomatosisSlide10

On US,

Wilms

tumor characteristically is a well-defined, predominantly solid mass arising from the kidney

Hypoechoic

or anechoic areas within the tumor represent necrosis.

Hydronephrosis

is commonly present.

Wilms

tumor has a propensity to extend into the renal vein, inferior vena cava, and RA; all of these structures must be evaluated preoperatively CT is used to evaluate large tumors and the lungs, which are a common site of metastasis. Either CT or MR can be used to exclude small masses in the

contralateral

kidney, which can be difficult to identify with US . Calcification is uncommon in

Wilms

tumor.Slide11

FIGURE 52.56.

Wilms

Tumor. A. The large, heterogeneous, left-sided tumor (T) shows a well-defined, enhancing rim (arrows). Note that the left renal parenchyma is stretched along the margin of the mass (claw sign), indicating an

intrarenal

mass. B. Tumor extension into the inferior vena cava (arrow) in another patient is seen with US. C. CT scan in a different child shows a large, partially cystic

Wilms

tumor (T) on the left and identifies a smaller

Wilms

tumor mass in the

contralateral

kidney (arrows).Slide12

Renal cell carcinoma is very rare in young children but sometimes occurs in older children and adolescents. Like

Wilms

tumor, renal cell carcinoma usually presents as an asymptomatic abdominal mass, although

hematuria

is sometimes present. Hypertension is less common with renal cell carcinoma than with

Wilms

tumor. The imaging characteristics of renal cell carcinoma are indistinguishable from those of

Wilms

tumor.Slide13

Other malignant tumors are rare in children. Clear-cell sarcoma and

rhabdoid

tumor of the kidney are highly aggressive

neoplasms

that were once considered variants of

Wilms

tumor. They are distinguished by a very poor prognosis and different metastatic patterns. The primary tumors have an imaging appearance identical to that of

Wilms

tumor, but bone metastases are common in clear-cell sarcoma, and

rhabdoid

tumor is associated with brain metastases and second intracranial primaries. Metastatic disease to the kidneys is uncommon. The kidneys may be infiltrated by leukemia or lymphoma, causing diffuse enlargement or multiple masses Slide14

FIGURE 52.57. Renal Lymphoma. Multiple nodular tumor masses (arrows) are visible within the enlarged kidney on US.Slide15

Mesoblastic

nephroma

is the most common renal tumor of the neonate. Like

Wilms

tumor,

mesoblastic

nephroma

arises from the

metanephric

blastema

, and these tumors are indistinguishable on US. Although

mesoblastic

nephroma

is usually considered benign, metastasis occasionally occurs (82,83).Slide16

Adrenal Hemorrhage

Adrenal masses characteristically cause downward and outward displacement of the kidney. In the newborn, the most common cause of adrenal enlargement is adrenal hemorrhage. Predisposing factors include large babies, obstetric trauma, neonatal sepsis, and hypoxia. The infants may present with an abdominal mass, jaundice, hypotension, or anemia, but small hemorrhages may go unnoticed. Hemorrhage occurs more frequently on the right and is occasionally bilateral. Older children develop adrenal hemorrhage as a result of accidental trauma, child abuse, meningococcemia, or anticoagulant therapySlide17

US is an ideal modality for evaluating adrenal hemorrhage. The normal adrenal gland in the newborn is larger and more easily visualized than that of the adult. The gland appears as an inverted

Vâ

€“shaped structure with an

echogenic

central region and a peripheral

hypoechoic

zone. Slide18

FIGURE 52.58. Normal Adrenal Gland. Note the characteristic

“Yâ

€ shape (arrow) of the normal adrenal gland sitting astride the

kidnSlide19

Hemorrhage enlarges the gland and causes loss of the V shape. Initially, the hematoma resembles a solid,

echogenic

mass

.

As the hemorrhage resolves, it becomes increasingly

hypoechoic

, starting in the central region and progressing peripherally

.

The hematoma decreases in size within the first week and sometimes calcifies. The calcifications begin around the rim of the gland, but eventually a small, completely calcified gland remains. Adrenal insufficiency rarely develops. Adrenal hemorrhage may be complicated by compression of the kidney, renal vein thrombosis, or infection.Slide20

FIGURE 52.59. Adrenal Hemorrhage. A. In the early stages, hemorrhage into the adrenal gland presents as an

echogenic

suprarenal mass (arrows). B. A resolving adrenal hemorrhage in a different infant appears cystic centrally on US (arrows).Slide21

Neuroblastoma

belongs to a group of neural crest origin tumors that range from the benign

ganglioneuroma

to the highly malignant

neuroblastoma

.

Neuroblastoma

arises from the adrenal gland or from sympathetic ganglia in the

retroperitoneum

, posterior

mediastinum

, neck, or pelvis. It is a neoplasm of early childhood, presenting in children younger than 5 years of age. Most children present with advanced disease and large abdominal masses. Symptoms are often related to bone metastases or

intraspinal

extension. In contrast to

Wilms

tumor,

neuroblastoma

is a poorly

marginated

mass that frequently extends across the midline and into the chest. The kidney may be invaded, causing the tumor to be mistaken for an

intrarenal

mass (Fig. 52.60ASlide22
Slide23

FIGURE 52.60.

Neuroblastoma

. A. Note the large, ill-defined, heterogeneous left abdominal mass (arrows). The mass crosses the midline and secondarily invades the left kidney. B. Radiograph shows a large soft tissue mass that displaces the right kidney inferiorly. Irregular, amorphous calcifications are seen within the mass (arrow). C. MR in a different patient shows a large mass (M) displacing the left kidney (K). A second tumor mass is identified adjacent to the spine in the right upper

hemithorax

(arrow). D. Axial T1WI in another patient clearly shows tumor extension into the spinal canal (arrows).Slide24

Most

neuroblastomas

appear

echogenic

and heterogeneous. In some cases, a characteristic

echogenic

nodule can be identified within the larger part of the tumor mass. CT and MR can be used to better define the extent of involvement of large tumors and to detect metastatic deposits .

Neuroblastoma

metastasizes to the liver, lymph nodes, and bone marrow. MR demonstrates

intraspinal

extension , bone marrow infiltration, and encasement of blood vessels without using IV contrast. Skeletal metastases are shown with technetium bone

scintigraphy

. Iodine-131-meta-iodobenzylguanidine is a tracer that resembles

norepinephrine

and is metabolized by

neuroblastoma

,

pheochromocytoma

, and other catecholamine-producing tumors.

Octreotide

is a

ligand

for G-protein receptor cell membranes. These two tracers have improved detection of primary tumor and metastases in some cases Slide25

Diffuse adrenal enlargement occurs with

adrenocortical

hyperplasia, which causes

adrenogenital

syndrome. The enlarged adrenals may have an undulating configuration, described as

cerebriform

. Marked, reversible adrenal enlargement is seen in infants treated with

adrenocorticotropic

hormone for infantile spasm

Wolman disease is a rare

lipidosis

that results in enlarged, densely calcified adrenal glands. Plain films are usually diagnostic. Wolman disease is usually fatal at an early ageSlide26

FIGURE 52.61. Congenital Adrenal Hyperplasia. Note the undulating configuration of the enlarged adrenal glandSlide27

Hepatobiliary

Masses

A variety of cystic and solid masses may arise from the liver and

biliary

tract in children Most conditions can be differentiated with US.

Acute

hydrops

of the gallbladder is a poorly understood condition probably caused by transient obstruction of the cystic duct. It has been associated with the

mucocutaneous

lymph node syndrome (Kawasaki disease); however, in many cases the cause is unknown. US shows a markedly enlarged, tender gallbladder with a thin wall. Acute

acalculous

cholecystitis

causes similar gallbladder enlargement, but the gallbladder distension is less pronounced and gallbladder wall thickening is present. Transient distension of the gallbladder sometimes occurs in the neonate, particularly in premature infants. Prolonged total

parenteral

nutrition and sepsis have been implicated as possible etiologic factorsSlide28
Slide29

Appendiceal

abscess

Genitourinary

   Ovarian cyst

Abdominoscrotal

hydrocele

Hydrometrocolpos

Urachal

cyst

Teratoma

/

dermoid

cyst

Miscellaneous

   CSF

pseudocystSlide30

Choledochal

cysts are congenital malformations of the

intrahepatic

or

extrahepatic

bile ducts. Multiple factors probably lead to the development of

choledochal

cysts, but the majority of cysts are associated with an anomalous junction of the common bile duct and pancreatic duct (abnormal

pancreatobiliary

junction [APBJ]). The APBJ allows pancreatic enzymes to reflux into the common bile duct, which may lead to inflammation and weakening of the bile duct wall. Jaundice, pain, and a right upper quadrant mass comprise the classic triad of findings seen with a

choledochal

cyst. Young infants more commonly present with fluctuating jaundice, pain, and feverSlide31

The most common type of

choledochal

cyst (type 1) is a localized,

fusiform

or

saccular

dilation of the common

bile duct below the cystic duct.

Choledochal

cysts are usually diagnosed by US, appearing as a cystic mass in the

porta

hepatis

, separate from the gallbladder and associated with dilated

intrahepatic

ducts

Hepatobiliary

scintigraphy

confirms that the cyst communicates with the

biliary

tract, aiding in differentiation from other cystic abdominal masses MR

cholangiopancreatography

may provide more detailed information about bile duct anatomy and anatomic relationships to adjacent structures Slide32

FIGURE 52.62.

Choledochal

Cyst. A. US shows a large,

multilobulated

anechoic cyst (C) that is adjacent to, but separate from, the gallbladder (arrows). B.

Cholangiography

confirms the presence of a large

intrahepatic

choledochal

cyst (arrows) involving the right hepatic duct. GB, gallbladder. C. CT scan of a different child shows a well-defined cyst in the

porta

hepatis

(arrow) associated with dilated central hepatic ductsSlide33

Hepatic cysts are less common in infants and children than in adults. Solitary congenital cysts of the liver are usually encountered as an incidental finding at US or CT. The cyst walls are thin and the fluid is anechoic on US. Some cysts are very large and

pedunculated

, and their hepatic origin may be difficult to ascertain. Multiple hepatic cysts occur in patients with

autosomal

dominant polycystic disease. Acquired hepatic cysts may be solitary or multiple and are most commonly of infectious origin (Fig. 52.63). Resolving hematoma of the liver may also appear as a well-defined cystic lesionSlide34

FIGURE 52.63. Candida Abscess of the Liver. Two irregular cystic collections with peripheral

echogenicity

are liver abscesses in this newborn infant with Candida sepsisSlide35

Hemangioendothelioma

is the most common benign liver tumor encountered in infancy . This vascular lesion may be solitary or multiple and is associated with

cutaneous

hemangiomas

in 40% of cases.

Hemangioendothelioma

may be complicated by high-output cardiac failure,

hemorrhage, jaundice, hemolytic anemia, or thrombocytopenia because of sequestration of platelets within the tumor. The typical

sonographic

appearance is a solid or complex mass associated with large feeding and draining vessels, seen best with color Doppler US The mass is well circumscribed and low in attenuation on CT and shows predominantly peripheral contrast enhancement. High signal intensity is seen on T2WIs, with multiple flow voids throughout the lesion representing vessels. The tumor may be treated with steroids, but arterial

embolization

or surgery may be needed in more symptomatic cases

.Slide36
Slide37

FIGURE 52.64. (Color Plates) Vascular

Neoplasms

of the Liver. A. This solitary

hemangioendothelioma

appears

echogenic

on US, with multiple

hypoechoic

vascular channels. B. Color flow Doppler shows the large feeding and draining vessels of the

hemangioendothelioma

. C. Multiple

sonolucent

liver masses (arrows) represent

hemangioendotheliomas

. D.

Arteriography

demonstrates the marked

vascularity

(arrows) of a

hemangioendothelioma

.Slide38

Mesenchymal

hamartoma

is an uncommon benign tumor seen most often in infants and young children.

Hamartomas

are usually solitary and predominantly cystic, with multiple thin

septations

and intervening nodules of solid tissue apparent on US. CT shows multiple areas of low attenuation within the tumor mass.

Hepatic adenomas are rare in childhood but have been reported in association with

Fanconi

anemia, glycogen-storage disease type 1, Hurler disease, and severe combined immunodeficiency

.Slide39

Focal nodular hyperplasia presents as a

masslike

lesion that most likely represents a

hyperplastic

response to a congenital

arteriovenous

malformation.

Scintigraphy

using sulfur colloid demonstrates normal to increased tracer uptake in many cases, differentiating it from adenomas that do not concentrate the tracer. On CT, the lesions show early phase enhancement but become

isoattenuating

with the liver on delayed images. An enhancing central scar may be seen.Slide40

Metastatic Disease

Neuroblastoma

is the most common childhood tumor to metastasize to the liver, followed by lymphoma, leukemia, and

Wilms

tumor. Metastatic lesions are usually multiple, and their imaging appearance is generally nonspecificSlide41

Hepatoblastoma

is a tumor of early childhood, presenting before 3 years of age . The tumor is more common in children with Beckwith-

Wiedemann

syndrome and familial

adenomatous

polyposisSlide42

FIGURE 52.65.

Hepatoblastoma

. A CT scan demonstrates a large inhomogeneous tumor within the right lobe of the liver (arrows).Slide43

Hepatocellular

carcinoma is more commonly seen in older children and adolescents.

Sonographically

, these tumors appear as single or multiple

hyperechoic

lesions, sometimes containing

hypoechoic

or anechoic areas because of hemorrhage or necrosis. Invasion of the hepatic or portal veins may be identified. On CT, the tumors appear as low-attenuation lesions with variable contrast enhancement. MR is comparable with CT for the initial diagnosis of these tumors; however, MR is more sensitive in the detection of postoperative tumor recurrence . MR angiography with three-dimensional reconstruction helps to evaluate tumor blood supply for surgical planning. Complete resection is required for survival, and

orthotopic

liver transplantation has been successful in some advanced cases of

hepatoblastoma

that would otherwise be

unresectable

. PET-CT promises to be a more sensitive

modality for identifying tumor metastases and local recurrence (Slide44

Other less common primary malignant tumors in children include undifferentiated (

embryonal

) sarcoma and

embryonal

rhabdomyosarcoma

of the

biliary

ducts. The latter tumor typically occurs in children between 2 and 5 years of age. When the tumor originates in a major bile duct, the patient presents with jaundice. Those tumors that originate within the

intrahepatic

ducts cannot be differentiated from other primary malignancies of the liverSlide45

Splenic

Lesions

Splenomegaly

is a relatively common cause of a left upper quadrant mass in children.

Splenic

enlargement is most often secondary to a systemic illness. Common causes include hematologic diseases, infections, portal hypertension, and infiltrative diseases (

mucopolysaccharidoses

,

reticuloendothelioses

, leukemia, and lymphoma). P.1320

The imaging characteristics are usually nonspecific and insufficient for diagnosing the cause of

splenomegaly

.Slide46

In the newborn and young infant,

splenomegaly

most often occurs because of bacterial sepsis and infection.

Hepatomegaly

is generally also present. In older children, infections such as infectious mononucleosis, typhoid fever, and

catscratch

fever are more common. Multiple small, poorly defined

hypoechoic

lesions can be seen with US in

granulomatous

splenic

infection such as

Bartonella

(

catscratch

fever), tuberculosis, or fungal infection.

Splenic

abscess is uncommon in children and is most often associated with an impaired immune systemSlide47

FIGURE 52.66.

Catscratch

Disease. US demonstrates the multiple

hypoechoic

nodules in the spleen (arrows) that are characteristic of this infectionSlide48

Cystic masses of the spleen are uncommon and include congenital

epidermoid

cysts, posttraumatic

pseudocysts

, and

echinococcal

cysts . Cystic

lymphangiomatosis

is a benign lymphatic malformation with a characteristic

multiloculated

cystic appearance. The lesion may contain calcification and enhances on CTSlide49

Splenic

Neoplasms

Primary

neoplasms

of the spleen (

hemangioma

,

hamartoma

,

angiosarcoma

) are rare. Lymphoma and leukemia commonly involve the spleen. However,

splenic

involvement with lymphoma does not necessarily result in

splenic

enlargement. Conversely, children with leukemia or lymphoma may have an enlarged spleen without

neoplastic

involvement.

Hemophagocytic

lymphohistiocytosis

(HLH) is a rare disease that consists of overactive

histocytes

and macrophages that

phagocytize

the normal cellular structures of the blood. This condition

is not truly malignant and is probably caused by an inappropriate immune reaction. HLH usually occurs in infants under 1 year of age and is characterized by

hepatosplenomegaly

,

ascites

, gallbladder wall thickening,

lymphadenopathy

, and pleural effusion .Slide50
Slide51

Splenic

Infarction

In children, infarction of the spleen occurs most often as a complication of sickle cell anemia, leukemia,

Gaucher

disease, or cardiac

valvular

disease. Acute

splenic

infarction results in decreased

echogenicity

on US and diminished or mottled enhancement on CT. Rarely, a poorly fixed (

“wanderingâ

€) spleen may undergo torsion, leading to infarction Slide52
Slide53
Slide54
Slide55
Slide56
Slide57
Slide58
Slide59
Slide60
Slide61
Slide62
Slide63
Slide64
Slide65
Slide66
Slide67
Slide68
Slide69