Pediatrics

Question 1

Bilateral Hydronephrosis w/ prenatal history

Answer 1

While bilateral hydroureteronephrosis could be related to several etiologies, the most concerning of these in a male neonate is posterior urethral valves. A delay in diagnosis and treatment of this disorder may result in chronic renal failure. The confirmatory study is a fluoroscopic voiding cystourethrogram, which will demonstrate the relevant urethral anatomy. The study should be performed as soon as possible to initiate early treatment.

Question 2

Omphalocele

Answer 2

Omphalocele has numerous associated syndromes and chromosomal anomalies including Beckwith-Wiedemann, OEIS (omphalocele, bladder extrophy, imperforate anus, and spinal anomalies), and pentalogy of Cantrell. Malrotation occurs in 100% of cases due to lack of normal mesenteric fixation.

Question 3

Omphalocele

Answer 3

Omphaloceles may be classified as small (< 5 cm) or giant ( > 5 cm). The former are more likely to contain only bowel and be associated with chromosomal anomalies (such as trisomies 13 and 18), while the latter are more likely to contain multiple abdominal viscera (including the entire liver). Unlike gastroschisis, omphalocele is associated with numerous additional congenital anomalies, which affect the overall prognosis of the baby.

Question 4

Pyelonephritis

Answer 4

The classic appearance of pyelonephritis is 1 or multiple wedge-shaped foci of cortical decreased renal perfusion/enhancement on cross-sectional imaging, as seen on the CT scan in this case. Grayscale sonography may show increased or decreased echogenicity at these levels with loss of corticomedullary differentiation, also seen here, and there is frequently generalized swelling.

Question 5

Cross-Fused Renal Ectopia

Answer 5

The classic appearance of pyelonephritis is 1 or multiple wedge-shaped foci of cortical decreased renal perfusion/enhancement on cross-sectional imaging, as seen on the CT scan in this case. Grayscale sonography may show increased or decreased echogenicity at these levels with loss of corticomedullary differentiation, also seen here, and there is frequently generalized swelling.

Question 6

Atrioventricular Septal Defect

Answer 6

enlargement of the right atrium with global cardiomegaly and increased pulmonary vascularity. A septum primum atrial septal defect is seen with a large ventricular septal defect and a common atrioventricular valve.
Patients with atrioventricular septal defect often have Down syndrome. It is important to look for imaging evidence of pulmonary disease in these patients, as it may have a significant impact on the post-surgical recovery. Patients with Down syndrome often have peripheral lung cysts, tracheobronchomalacia, and a higher incidence of a right upper lobe tracheal bronchus.

Question 7

Elbow Ossification

Answer 7

• It is important to understand the normal ossification time line of the growth centers about the elbow. The standard mnemonic is CRITOE: Capitellum, Radius, Internal (medial) epicondyle, Trochlea, Olecranon, and External (lateral) epicondyle. An ossified fragment that cannot be explained by this mnemonic needs to be thoroughly investigated. In this case, the proximal radial epiphysis is not yet ossified; therefore, the faint bony fragment adjacent to the capitellum must be from a fracture. Although the growth cartilage of the condyle is not yet ossified and cannot be appreciated on radiographs, lateral condylar fractures always extend through the cartilage to the articular surface. They therefore are considered a Salter-Harris IV injury and an orthopedic urgency.

Question 8

Legg-Calve-Perthes

Answer 8

Legg-Calve-Perthes disease is an idiopathic osteonecrosis of the femoral head that most commonly presents with limp over weeks to months in 4 to 8-year-old females or 5 to 9-year-old males. Males are much more frequently affected than females (4-5:1). Up to 20% of cases occur bilaterally but this is rarely synchronous or symmetric. Long-term complications include growth arrest with limb length discrepancy and early degenerative disease.

Question 9

Meconium Peritonitis

Answer 9

Meconium peritonitis results from an in utero bowel perforation with spillage of meconium into the peritoneal cavity. Calcification of these extraluminal contents occurs rapidly. The primary etiologies for such in utero bowel perforations include bowel atresias, meconium ileus (from cystic fibrosis), volvulus, and internal hernia. Given the number of dilated bowel loops, contrasted enema would be the next best step to evaluate the site of obstruction in this patient.

Question 10

Lumbosacral Myelomeningocele

Answer 10

• The intracranial findings of Chiari 2 malformation (including hindbrain herniation , tectal beaking , towering cerebellum , and elongation/effacement of the 4th ventricle ) are secondary to a chronic in utero cerebrospinal fluid leak through an open neural tube defect

Question 11

Crainopharyngioma

Answer 11

• pediatric suprasellar mass containing calcifications, cystic components, foci of T1 shortening (that are due to proteinaceous fluid and not fat–as confirmed on CT in this case), and foci of enhancement is almost always a craniopharyngioma.
• Craniopharyngioma is a benign tumor accounting for 9% of pediatric intracranial neoplasms. It is most commonly seen between ages 8-12 and presents with symptoms secondary to hydrocephalus (i.e., headache, vomiting, etc.) versus those due to local mass effect (e.g., visual symptoms due to optic chiasm compression or hormonal disturbances from pituitary or hypothalamic compression). The adamantinomatous subtype is found in children, while the squamous-papillary subtype is seen in adults. Treatment is surgical resection, which can have a high morbidity due to the intimate relationship of the tumor with important structures (i.e., hypothalamic injury may result in diabetes insipidus or compulsive eating). Ten year survival is up to 96%. However, recurrence is high if the tumor is larger than 5 cm (which is common).

Question 12

Medulloblastoma

Answer 12

• Medulloblastoma is usually centered in the 4th ventricle. It is usually hyperdense on CT and does not extend through the foramen of Magendie.
• However, the generally hyperdense CT appearance and T2 isointensity to gray matter of the lesion makes medulloblastoma the most likely choice.

Question 13

Pilocytic Astrocytoma

Answer 13

Pilocytic astrocytoma can have a variety of appearances, including a heterogeneously enhancing solid mass. The classic appearance of a posterior fossa juvenile pilocytic astrocytoma is that of a cystic lesion with an enhancing mural nodule that does not extend out of the foramen of Magendie.

Question 14

Ependymoma

Answer 14

• Ependymoma is 1 of the 3 main central nervous system tumors that must be considered when a mass arises in the 4th ventricle of a child. Ependymoma classically extends through the outlets of the 4th ventricle (such as the foramen of Magendie, and the foramina of Luschka) into the surrounding cerebrospinal fluid spaces
• This lesion classically arises from the floor of the 4th ventricle. Calcifications, cysts, and hemorrhage are often seen in the mass. A common imaging finding is extension through the foramen of Magendie and Luschka

Question 15

Callosal Dysgenesis

Answer 15

• Callosal dysgenesis is a congenital malformation resulting in hypoplasia or absence of all or part of corpus callosum, which is usually identified in early childhood. The presence of an associated midline anomaly, such as a cyst or lipoma, varies. Callosal dysgenesis is the most common anomaly seen with other central nervous system (CNS) malformations, and syndromic associations are common. Don’t stop with the obvious, look for additional abnormalities!
• Pericallosal lipomas are highly associated with callosal dysgenesis and may be your best hint at subtle forms of dysgenesis. Remember that the corpus callosum forms from front (the genu) to back (the splenium), and therefore the splenium is the most likely part of the corpus to be absent in cases of partial agenesis of the corpus callosum.

Question 16

Uteropelvic junction obstruction

Answer 16

• Ureteropelvic junction (UPJ) obstruction is typified by dilation of the renal pelvis and calyces without hydroureter. The largest collection of fluid is seen centrally at the renal pelvis, which is contiguous with fluid extending into the calyces. The nuclear medicine renal scan is typical of a high grade UPJ obstruction with delayed excretion of radiotracer into the dilated renal pelves. Unlike the other listed diagnoses, radiotracer does not freely pass into the ureter with a UPJ obstruction (as noted in this case). The persistence of most of the activity in the dilated renal pelves more than 20 minutes after peak activity (i.e., increased T1/2 max) is consistent with high-grade obstruction.

Question 17

Schizencephaly

Answer 17

• The key imaging feature of schizencephaly is identifying a gray-matter lined cleft extending deep from the superficial cortical or pial brain surface to the ependymal surface of the lateral ventricle. This is easiest when the cleft is wide and contains cerebrospinal fluid (open lip schizencephaly). The cleft is more difficult to visualize when it is narrow with apposition of the lining gray matter along the cleft (closed lip schizencephaly). An outward dimpling of the lateral ventricular ependymal surface may be the only clue to the presence of a cleft in these cases. The gray matter lining the cleft is always dysplastic or polymicrogyric. Look for signs of septo-optic dysplasia (absent cavum septi pellucidi, small optic nerves) due to the high association of these entities. The incidental arachnoid cyst in this case has typical features (simple extraaxial cyst, minimal mass effect, usual location); these have occasionally been reported in cases of schizencephaly.
• Large bilateral cerebral clefts filled with cerebrospinal fluid and lined by gray matter, typical of open-lipped schizencephaly.

Question 18

Tetralogy of Fallot

Answer 18

• The combination of a subaortic ventricular septal defect, an overriding aorta, and right ventricular hypertrophy are typical of tetralogy of Fallot. There is a recognized variant of absent pulmonic valve with severe regurgitation (rather than the typical infundibular pulmonic stenosis), leading to enlarged pulmonary arteries.

Question 19

Claw Sign

Answer 19

• The “claw sign” is an ultrasound, CT, or MR imaging finding of attenuated residual renal parenchyma splayed along the margins of a mass. This finding strongly suggests a renal origin to the tumor. In younger age group, the most common renal neoplasm is a Wilms tumor.

Question 20

Meconium on MRI

Answer 20

• The bright signal is an expected finding caused by the T1 shortening properties of meconium, a well-documented but not clearly elucidated phenomenon. Knowledge of this finding is important in fetal imaging because it can be used to identify normal and pathologic patterns in the fetal GI tract

Question 21

Bronchial Foreign Body

Answer 21

• Decubitus radiographs confirm unilateral air-trapping when the abnormal side does not show relative deflation when it is placed down. A bronchial foreign body should be the primary suspect when asymmetric pulmonary hyperinflation is noted involving an entire lung, particularly if there is sudden onset of symptoms.

Question 22

Diffuse Cerebral Edema

Answer 22

• Though the cortical hyperdensities seen on the follow-up CT are uncommon, the other progressively worsening brain changes seen in this case (including diminished gray-white matter differentiation, relative hyperdensity of basal ganglia and cerebellum, and cerebral sulcal effacement) are classic for a diffuse cerebral insult with parenchymal swelling.

Question 23

Crohns

Answer 23

• Crohn disease is a granulomatous inflammatory bowel disease with a segmental distribution that most commonly involves the terminal ileum. In the acute setting, as seen here, there is often bowel wall thickening with no significant luminal narrowing. Occasionally, bowel wall thickening and acute inflammatory changes do cause luminal narrowing, and a small minority of children therefore present with an acute small bowel obstruction. However, luminal narrowing is usually seen in the chronic or cicatrizing phase of the disease.

Question 24

Pulmonary Interstitial Emphysema

Answer 24

• Pulmonary interstitial emphysema (PIE) is a form of barotrauma usually seen in the 1st few days of life. It occurs when there is rupture of overdistended pulmonary alveoli that leads to entry of air into pulmonary interstitium. The treatment of pulmonary interstitial emphysema can be difficult and the child may be imaged many times before the finding resolves. Often switching from conventional to high-frequency ventilation will help; other maneuvers include placing the infant in the decubitus positioning with the affected side down and selective intubation of opposite lung. Look for other signs of barotrauma, such as pneumothorax or pneumomediastinum. If the abnormality persists, surgical resection may be indicated to improve the child’s respiratory function.
• The age and appearance (of branching linear lucencies radiating from the hilum) are classic for pulmonary interstitial emphysema.

Question 25

Mature Ovarian Teratoma

Answer 25

• Mature teratomas are predominantly cystic with dense calcifications, whereas malignant immature teratomas are predominantly solid with small foci of lipid material and scattered calcifications. Immature teratomas are typically larger than mature teratomas.
• Mature ovarian teratomas (aka dermoid cysts) account for 2/3 of pediatric ovarian tumors. Two-thirds of these patients present with an abdominal mass. Ovarian teratomas can be associated with various complications, including torsion, rupture, malignant transformation, infection, and autoimmune hemolytic anemia.

Question 26

HSV Encephalitis

Answer 26

• As seen in this case, herpes simplex virus meningoencephalitis classically affects the medial temporal lobe. Restricted diffusion is frequently noted, and hemorrhage occurs later in the clinical course.
• Herpes simplex virus (HSV) encephalitis can have devastating consequences, and early initiation of IV acyclovir is key for effective therapy. Neonatal HSV encephalitis can affect any lobe, while HSV in older children has a predilection for inferior frontal and temporal lobes.

Question 27

Multicystic Dysplatic Kidney

Answer 27

• a multicystic dysplastic kidney (MCDK) is a nonfunctional kidney, replaced by multiple variably sized, noncommunicating cysts, and dysplastic tissue.
• Up to 40% of patients with multicystic dysplastic kidney (MCDK) have a contralateral renal abnormality (ureteropelvic junction obstruction and vesicoureteral reflux are the most common). They tend to involute over time with decreasing size of cysts and no recognizable renal parenchyma. MCDK has cysts of varying size that do not interconnect, unlike massive hydronephrosis. Intervening parenchyma tends to be echogenic fibrous tissue. Nuclear scintigraphy documents lack of renal function, confirming the diagnosis of MCDK.

Question 28

Hypertrophic Pyloric Stenosis

Answer 28

• With hypertrophic pyloric stenosis (HPS), a pyloric US will show several important findings. The most confirmatory of these is an unchanging pyloric muscle, which is abnormally thickened and lengthened at minimum distances of 3 mm and 15 mm, respectively (with thickness measuring a single wall, not both walls). With intermittent observation over several minutes, the pylorus should not show relaxation, opening, or more than a minimal thin string of gastric contents passage to the duodenum. Additional findings may include hypertrophy of the central echogenic pyloric mucosa and distention of the stomach by retained ingested material.

Question 29

Legg-Calve-Perthes

Answer 29

• Legg-Calve-Perthes disease is an idiopathic osteonecrosis of the femoral head which most commonly presents with limp over weeks to months in 4-8 year old females or 5-9 year old males. Males are much more frequently affected than females (4-5:1). Up to 20% of cases occur bilaterally but this is rarely synchronous or symmetric. The amount of femoral head involvement, preservation of femoral head “lateral pillar” height, degree of collapse of the femoral head, extent of femoral head extrusion from the acetabulum, range of motion, and age of onset determine prognosis. Treatment generally involves rest and bracing with abduction casting but surgery may be performed with acetabuloplasty to contain the femoral head. Long-term complications include growth arrest with limb length discrepancy and early degenerative disease.
• Legg-Calve-Perthes disease is most commonly detected radiographically with irregularity, flattening, sclerosis, and fragmentation of the femoral head ossification center. Absent perfusion of the femoral head on nuclear medicine bone scan (as seen in this case) is typical though foci of increased perfusion may occur with revascularization. MRI signal will also vary with the stage of disease but will frequently show mixed foci of increased and decreased enhancement

Question 30

Meconium Aspiration Syndrome

Answer 30

• The typical pattern of meconium aspiration syndrome is coarse bilateral (often rope-like perihilar) lung opacities with increased lung volumes in a term infant. Pleural effusion is uncommon. Mechanical obstruction of small airways due to the tenacious nature of meconium results in air-trapping and complications, such as pneumothorax (20-40%), pulmonary intersitial emphysema, and pneumomediastinum.

Question 31

Congenital Lobar Emphysema

Answer 31

• The lower segments of the right lower lobe are hyperlucent and hyperexpanded. There is no atretic bronchus, cyst, or vascular anomaly as expected in other diagnoses. These parenchymal findings are typical of the over-distension of a pulmonary lobe due to obstruction, seen in congenital lobar emphysema.

Question 32

Exudative Tracheitis

Answer 32

• Close inspection of the tracheal wall shows mild irregularity and plaque-like filling defects, compatible with exudative tracheitis. The age is older than classic for viral croup, and there are no signs of epiglottitis.
• Children with exudative tracheitis (bacterial croup) are usually older than children with typical viral croup. They are also much sicker with symptoms of fever and severe neck pain. The potential for airway occlusion by detachment of 1 of the membranes makes this a life-threatening emergency, and ENT consultation is emergent.

Question 33

Dandy Walker

Answer 33

• large posterior fossa with elevation of the torcular herophili (“torcular-lambdoid inversion”) and absence of the cerebellar vermis with communication of the 4th ventricle to the posterior fossa cyst.

Question 34

Benign Pneumatosis

Answer 34

• Gas tracking extensively through the wall of the cecum, ascending colon, and transverse colon without wall thickening, abnormal enhancement, or adjacent fluid or fat stranding. The small bowel is normal. In an older child (beyond time frame for the devastating entity of necrotizing enterocolitis in infancy), this is most likely a benign and self-limited form of pneumatosis, which can have a variety of causes in older children. Close clinical evaluation/observation and CECT are often required, however, to confirm that bowel ischemia is not the underlying cause. This point is particularly relevant in a patient with bloody stools (a finding that is clinically concerning for gut ischemia) who has a neurologic disorder (which may confound the clinical history and physical exam findings).

Question 35

Sacrococcygeal Teratoma

Answer 35

• A predominantly exophytic mixed cystic and solid mass arising from the perineum of a newborn is most likely a sacrococcygeal teratoma. Relatively small components are noted anterior to the sacrum in this case.

Question 36

Autosomal Recessive Polycystic Kidney Disease

Answer 36

• enlarged bilateral echogenic kidneys with numerous dilated tubules and cysts in a neonate with pulmonary hypoplasia are typical of autosomal recessive polycystic kidney disease
• There is a spectrum of severity of renal involvement in autosomal recessive polycystic renal disease, with the most severe form presenting in neonates with pulmonary hypoplasia and renal failure vs. those who present as older children with more severe liver disease.

Question 37

Meconium Ileus

Answer 37

• An obstruction of the distal small bowel due to blockage by thickened meconium. This is almost always a complication of cystic fibrosis with up to 15% of cystic fibrosis patients presenting in this manner. Up to half of these cases are complicated by in utero perforation (resulting in meconium peritonitis), volvulus, or atresia that will require surgery. Uncomplicated cases may be treated with serial hyperosmolar enemas to facilitate meconium passage, though some of these cases will not have relief of the obstruction and still require surgical removal of the meconium. The diagnosis is clear when contrast passes through a microcolon into a meconium packed ileum. If the obstruction by meconium is so great that contrast cannot be refluxed proximally into small bowel then an ileal atresia cannot be excluded and surgery is required for diagnosis. An equivalent complication of cystic fibrosis in older patients is referred to as distal intestinal obstruction syndrome (DIOS).

Question 38

Bronchopulmonary Dysplasia

Answer 38

• Chronic lung disease of prematurity
• Diffuse rounded lucencies in the chest.
• ill-defined reticular markings with interspersed rounded lucent areas diffusely involving hyperinflated lungs
• the lungs may have relatively normal AP diameter on the lateral film
• presence of cardiomegaly may indicate the development of pulmonary hypertension
  in chronic cases, the lateral film may show a much narrower AP diameter compared with the chest width on the frontal film

Question 39

Osgood Schlatter Disease

Answer 39

-There is fragmentation of the tibial tubercle ossification center with edema of the adjacent Hoffa fat and thickening of the distal patellar tendon.

Question 40

Ebstein Anomaly

Answer 40

• Massive dilatation of the right atrium and right ventricle with the septal leaflet of the tricuspid valve displaced towards the septum are classic findings for Ebstein anomaly.
• There is marked cardiac enlargement and a so-called “box-shaped” heart. Patients are sometimes cyanotic
• Audible murmur from bedside

Question 41

Pyelonephritis

Answer 41

• The wedge-shaped foci of edematous renal cortex (particularly at the poles) with decreased vascular flow (US) seen in this case are very typical of pyelonephritis. If this diagnosis was not suspected prior to imaging, urinalysis and culture is recommended

Question 42

Meconium Plug Syndrome

Answer 42

• Numerous dilated bowel loops in a neonate with failure to pass meconium suggests a distal intestinal obstruction that should be investigated with a contrasted enema. Meconium plug syndrome is the primary consideration for a narrowed distal colon extending up to the left colon or splenic flexure with more proximally dilated bowel.
• Also known as neonatal “small left colon,” this is an immaturity of the distal colon that is classically seen in patients whose mother received magnesium sulfate for preeclampsia or had diabetes. The underlying etiology is suspected to be an immaturity of colonic ganglion cells. A contrasted enema will show a small distal colon up to the level of the splenic flexure classically. Plugs of meconium may be visualized in the colon (though these are the result of the functional obstruction rather than its cause). This appearance cannot be differentiated from a high transition Hirschsprung disease. The initially abnormal distal colon of meconium plug syndrome typically acquires normal function within a few days of life. If the colon does not develop normal function within a few days, biopsy must be performed. Unlike meconium ileus, this diagnosis is unrelated to cystic fibrosis.

Question 43

Holoprosencephaly

Answer 43

• Fusion of the frontal lobes and thalami with a monoventricle that communicates with a large dorsal cyst, as seen here, is consistent with alobar holoprosencephaly.

Question 44

Prenatal - Autosomal Recessive Polycystic Kidney Disease

Answer 44

• Severe oligohydramnios and pulmonary hypoplasia, as seen here, are typical of severely impaired urine production or urinary tract obstruction. The prenatally detected bilateral renal enlargement of this case (without numerous macroscopic cysts or hydronephrosis) is typical of autosomal recessive polycystic kidney disease. The diffusely abnormal parenchymal signal is secondary to the underlying tubular dilation.

Question 45

Congenital Cystic Adamentoid Malformation. Congential Pulmonary Airway Malformation

Answer 45

There are 3 types of congenital cystic adenomatoid malformations (CCAM) (aka CPAM, congenital pulmonary airway malformation) that are based on the size of cysts in the lesion at imaging/pathology; type 1: 1 or more large (2-10 cm) cysts, type 2: numerous small cysts of uniform size, type 3: appears solid on gross inspection and imaging but have microcysts. They may be associated with deletions on chromosome 18, and type 2 lesions are associated with other congenital anomalies (50%) including renal, skeletal, intestinal, and cardiac anomalies. CCAMs are at risk for becoming infected, and there is a small reported risk for malignant degeneration (rhabdomyosarcoma). Most advocate surgical resection.

Question 46

Congenital Diaphragmatic Hernia

Answer 46

• One of the most classic findings of congenital diaphragmatic hernia (CDH) is a reverse J-shaped curvature to the gastric tube. This occurs because the vast majority of hernias are on the left and the stomach is among the herniated contents. As seen here, this helpful finding will NOT be seen when the patient has a RIGHT congenital diaphragmatic hernia. CDH is challenging from a medical and physiologic standpoint because these children have pulmonary hypoplasia and pulmonary hypertension. From a surgical standpoint, the repair is relatively straightforward and most pediatric surgeons will allow newborns with CDH to grow some before they repair the defect, usually waiting until the 2nd week of life.

Question 47

Germinal Matrix Hemorrhage

Answer 47

• Germinal matrix hemorrhage is diagnosed by newborn head ultrasound and classified grades I through IV. Newborns with grades I and II hemorrhage generally have a good prognosis. Those with grade III hemorrhage and those with grade III hemorrhage accompanied by hemorrhagic venous infarction (a.k.a. grade IV) generally have a much poorer outcome. Extension of intraventricular hemorrhage IS NOT the pathophysiology of grade IV hemorrhage; rather, grade IV represents hemorrhagic venous infarction in the setting of ventricular distention.

Question 48

Caudal Regression Syndrome

Answer 48

• hypogenesis of the embryologic caudal cell mass. The more severe type (type 1, seen here) has a shortened vertebral column with high position of a truncated conus medullaris whereas type 2 has a tethered cord with low conus position. The former has higher likelihood of severe associated anomalies including omphalocele, the VACTERL sequence (vertebral anomalies, anal atresia, cardiac anomalies, tracheoesophageal fistula, esophageal atresia, renal anomalies, and limb malformations), and the Currarino triad (with anal atresia and a presacral mass of a sacrococcygeal teratoma or anterior sacral meningocele). Most patients have neurogenic bladder while lower extremity neurologic impairment is variable.

Question 49

Bronchopulmonary dysplasia

Answer 49

• Another term for BPD is chronic lung disease of prematurity
• Bronchopulmonary dysplasia occurs in premature infants, usually less than 32 weeks gestation at birth. Nowadays, it is uncommon when infants were equal to or greater than 34 weeks gestational age at birth. There is increased risk for pulmonary infections in the first 2 years of life, especially with respiratory syncytial virus, with increased morbidity and mortality. Pulmonary function slowly improves with fewer respiratory infections later in childhood. Surviving infants may subsequently develop normal radiographs in childhood.