Pelvic Ewing's Sarcoma

A pelvic radiograph of a 5-year-old girl shows a large lytic lesion in the left iliac bone (arrows).

An axial FDG PET/CT image shows high metabolic activity of the mass involving the left iliac bone with soft tissue component and bone destruction. A coronal T2W MR image reveals an extensive soft tissue mass with necrotic areas and involvement of the adjacent musculature. 

Differential Diagnosis

• Metastatic neuroblastoma. Given her age at five years old, this needs to be in differentials
• Ewing's sarcoma
• Telangiectatic osteosarcoma
• Osteomyelitis. Great mimics of aggressive-looking bone tumor. Symptoms may overlap with round-cell tumor, including fever

This case: Ewing's sarcoma by tissue diagnosis (+ve PAS and vimentin).

Facts: Ewing's Sarcoma

• Malignant round-cell tumors of the bone with neural cell origin
• Tumors of children and young adults, most between 10-20 years old. Less than 2% occur in children less than 5 years old
• Most common sites = femur >> pelvis
• Pelvic Ewing's -- bad prognosis because there is no anatomic barrier to tumor spread, close proximity to viscera and neurovascular bundles, prone to recur

Reference:

Bhagat S, Sharma H, Pillai DS, Jane MJ. Pelvic Ewing's sarcoma: a review from Swedish Bone Tumour Registry. J Orthop Surg 2008;16:333-8

Mediastinal Neuroblastoma

Axial CT image at the level of mid thoracic spine of a 5-year-old boy shows a well-circumscribed, enhancing left paraspinal mass located between the medial ends of the ribs. 

An MIBG study (posterior view of the thorax and upper abdomen) shows a focus of moderate uptake in the left side of the lower thorax, corresponding with the site of abnormal mass on CT. Note intense uptake of bilateral adrenal glands. 

Facts: Neuroblastoma

• 8-10% of all childhood malignancies
• Malignant tumor composed of immature ganglion cells. Most (2/3) arise from abdomen or pelvis and the rest is extra abdominal
• Typically seen in children under age of 5 years
• Treatment determined by stage of tumor at presentation. Regionally limited disease is potentially resectable, but locally extensive or disseminated disease is usually not resectable
• Current imaging staging evaluation: 1) CT or MRI of primary tumor, 2) skeletal survey, 3) bone scintigraphy or MIBG for bone metastasis, and 4) bone marrow aspiration and biopsy for marrow disease
• CT alone has low sensitivity (43%) but high specificity (97%) for detection of stage 4 disease. CT accuracy = 81%. MRI is more sensitive (83%) but less specific (88%) and slightly more accurate (85%). 

Imaging Findings: CT/MRI

• Sharply marginated, fusiform paraspinal mass
• Oriented along direction of sympathetic chain
• 40% contain calcifications
• Heterogeneous enhancement
• Differentiation from ganglioneuroblastoma (usually 5-10 years old) and ganglioneuroma (usually > 10 years old) not possible by imaging. Basically, they are tumors of sympathetic ganglia

References
1. Siegel MJ. Pediatric Body CT. 2008
2. Siegel MJ, Ishwaran H, Fletcher BD, et al. Staging of neuroblastoma at imaging: report of the radiology diagnostic oncology group. Radiology 2002;223:168-175. 

Infected Second Branchial Cleft Cyst

Axial CT image of the neck in a 2-year-old boy shows a cystic lesion in the right neck anterior to the sternocleidomastoid muscle, lateral to the carotid space. There is wall enhancement and nearby fascial thickening and subcutaneous fat stranding.

Facts: Branchial Cleft Cyst

• Type II = most common (92-99% of all branchial cleft cysts)
• Anywhere along anterior aspect of sternocleidomastoid muscle, lateral to carotid sheath to parapharyngeal space at the level of palatine tonsil
• CT: fluid density unless infected or hemorrhagic
• MRI: T1 hypointense, T2 hyperintense (unless infected or hemorrhagic)
• Can be associated with fistula or sinus tract

Other Things To Consider: Necrotic lymph node/metastasis, dermoid, abscess, laryngocele, ectopic thymic cyst

What Surgeons Want To Know

• Infection? May need surgery if at risk of septicemia or abscess
• Mass effects? Compression of esophagus, airways
• Neoplasm?
• Treatment of infected branchial cleft cyst is different from simple abscess. In the former, I&D alone is not adequate but the entire cyst and its tract must be removed to prevent recurrence. Therefore, it is important that accurate diagnosis is made preoperatively.

Our case: infected second branchial cleft cyst

Reference:

1. Bailey BJ, Calhoun KH. Atlas of Head & Neck Surgery-Otolaryngology, 2001.

2. Lin EC, Escott EJ, et al. Practical Differential Diagnosis for CT and MRI, 2008.

Intussusception Reduction

A "scout" radiograph before intussusception reduction procedure shows a soft tissue mass (arrows) in the right upper quadrant representing the intussusception. There is no free air.

Contrast enema for reduction shows the intussusception (arrows) in the right upper quadrant. It was successfully reduced.

Facts

• Image-guided liquid or air reduction of intussusception is the treatment of choice
• Contraindications for image-guided reduction = peritonitis, free intraperitoneal air due to perforation, in shock or sepsis
• Choice between air, liquid, contrast enema reduction of intussusception depends on radiologist experience and local preference/practice. Most radiologists prefer to use air and it is now generally accepted as the technique of choice
• Air pressure: between 80 and 120 mmHg
• Contrast: bag positioned approximately between 3 ft and 6 ft above the patient
• Reduction rate between 80% to 95%

Preparation for Reduction

• Notify the referring physician and surgeon
• Patient must be stable, well-hydrated and has no evidence of peritonitis
• IV line in place
• A large-bore needle at hand (if you use air reduction)

Complications

• Perforation rates with air enema less than 1%
• Recurrence 10% of cases

Reference:

1. Daldrup-Link HE, Gooding CA. Essentials of Pediatric Radiology: A Multimodality Approach, 2010.

2. Hodler J, Von Schulthess GK, Zollikofer CL. Diseases of the Abdomen and Pelvis 2010-2013: Diagnostic Imaging and Interventional Techniques, 2010.

Intussusception: Ultrasound

A longitudinal US image shows a "pseudokidney" sign of intussusception (arrows). Arrowheads point to enlarged mesenteric lymph nodes within the intussusceptum.

A transverse US image shows a "target" sign with a hypoechoic ring of the intussuscepiens surrouning the central echogenic area of intussusceptum. Arrowheads point to enlarged nodes.

Facts

• A segment of bowel (intussusceptum) prolapses into a more distal bowel segment (intussuscepiens)
• Most frequently seen in the first two years of life but can be seen up to 4 years. If older child has intussusception, looks for a lead point such as polyp, Meckel diverticulum, lymphoma, duplication cyst.
• Classic triad: colicky pain, vomiting and bloody (red currant jelly) stools (seen in less than 25% of cases)
• X-ray is positive in only 50% of cases, and is not reliable in diagnosing this condition

Ultrasound Findings

• Modality of choice to diagnose intussusception
• "Target" sign = hypoechoic ring with an echogenic center on transverse US image
• "Pseudokidney" sign = hypoechoic bowell wall extending along a hyperechoic mucosa
• Helpful in searching for a lead point. US can provide a specific diagnosis in one-third of these cases.

Reference:

1. Daldrup-Link HE, Gooding CA. Essentials of Pediatric Radiology: A Multimodality Approach, 2010.

2. Hodler J, Von Schulthess GK, Zollikofer CL. Diseases of the Abdomen and Pelvis 2010-2013: Diagnostic Imaging and Interventional Techniques, 2010.

Child Abuse

A frontal radiograph of the femur demonstrates classic metaphyseal lesions of the distal femur and proximal tibia medially (arrows)

Facts:

• The two most common injuries in child abuse = soft tissue injuries and fractures
• Failure to recognize child abuse may result in the child's return to hostile environment, leading to repeated injuries and possible death
• Highly specific fractures = rib, spinous process, and sternal fractures and classic metaphyseal lesions
• High suspicion = multiple fractures of differing ages

The Skeletal Survey

• To evaluate children less than 2 years old for signs of physical abuse
• American College of Radiology (ACR) recommends a single frontal view of each region of the appendicular skeleton (arms, forearms, thighs, legs, hands and feet), frontal and lateral views of the axial skeleton (skull, C-spine, LS spine and thorax) and a frontal view of the pelvis <=== these are a minimum of 20 radiographs
• In a recent report of 930 abused children, prevalence of fractures was 34%. Skeletal survey added value in 13% of cases in which new fractures were discovered only at skeletal survey but not on prior imaging. Most fractures occur in long bones, ribs and skull. Pelvis, spine, hands and feet were much less common to be fractured (only 1% of all cases, which also had other fractures diagnostic of abuse). The authors called for eliminating x-rays of the pelvis, spine, hands and feet from skeletal survey performed for suspected child abuse

Reference:

Karmazyn B, Lewis ME, Jennings SG, et al. Prevalence of uncommon fractures on skeletal surveys performed to evaluate for suspected abuse in 930 children: should practice guidelines change? AJR 2011; 197:W159-W163.

Lumbosacral Agenesis

Authors: Sanjay B. Nathani, M.D. (Radiodiagnosis), J.P. Agarwal, M.D. (Paediatrics).

Editor: Rathachai Kaewlai, M.D.

Fig. 1: There is poor development of the lower extremities with popliteal webbing, deformed hip, ankles and calcaneus.

Fig. 2: AP and lateral spinal radiographs demonstrate absence of normal vertebra distal to T12, with L1 and L2 hemi- and butterfly vertebra. The sacrum is absent. Both iliac bones articulate with each other resulting in decreased transverse pelvic diameter.

Fig. 3: T1W and T2W sagittal MR images of the spine shows complete agenesis of L3, L4, L5 and sacrum. Conus medullaris ends at the level of T8 with a blunted tip. The distal thecal sac tapers to a narrow channel at T12.

Brief Facts

• Caudal regression syndrome is characterized by absence of segment(s) of the lumbosacral spine
• Unknown etiology but associated with maternal insulin-dependent diabetes
• Associated with multiple congenital anomalies
• On radiography, absence of segment(s) of lumbosacral spine is characteristic. There may be fusion of the iliac bones resulting in small pelvis.
• MR imaging provides information about the position and appearance of conus medullaris, which defines two distinct groups of this disease. In group I the conus ends cephalad to the lower border of L1. In group II the conus terminates below L1 known as tethered cord.

Facts

Caudal regression syndrome is a rare congenital malformation characterized by absence of variable segments of lumbosacral spine. The etiology of the syndrome is unknown. It is possibly associated with maternal insulin-dependent diabetes (16% - 50% of cases). A dominant inheritant form of lumbosacral agenesis has been shown to result from defects in the HLXB9 homeobox gene mapping to chromosome 7q36. This gene is also expressed in pancreas perhaps accounting for the association of lumbosacral agenesis with insulin and diabetes.

Motor deficits are present and correspond to the level of vertebral agenesis. Associated conditions are OEIS complex (omphalocele, cloacal extrosphy, imperforate anus, spinal deformities), VATER syndrome, congenital heart defects, genitourinary complaints with unilateral renal agenesis, hydronephrosis, pelvic and horseshoe kidneys, epispadias and hypospadias, orthopedic deformities such as hip dislocation, flexion contractures, genu recurvatum, posterior compartment atrophy, talipes deformities and scoliosis, progressive neurological deficits and back and leg pain, uterine anomalies or rectovaginal fistulas.

Renshaw reviewed 22 patients over 18 years and proposed a classification as follows:

Type I - total or partial unilateral sacral agenesis

Type II - partial sacral agenesis but bilaterally symmetrical defect

Type III - variable lumbar and total sacral agenesis with the ilia articulating with the sides of the lowest vertebra present

Type IV - variable lumbar and total sacral agenesis with the caudal endplate of the lowest vertebra resting above either fused ilia or an iliac amphiarthrosis.

As seen on MR imaging, the position of the conus defines two distinct groups of patients with sacral agenesis. In group I, the conus ends cephalic to the lower border of L1. The conus typically deforms and terminates abruptly at T11 or T12 as if the normal distal tip was absent. The distal central canal may be slightly dilated as a terminal hydromyelia. In this group, the sacrum usually ends at or above S1. Coronal T1WI will show Christmas tree configuration formed by the distal thecal sac, root sleeves and nerve roots within the epidural fat of the spinal canal.

In group II, the conus ends lower, below L1, and is elongated, tethered by a thick filum. There can be associated terminal myelocystocele, transitional lipoma, or elongated cord with terminal hydromyelia. Neurological deficit is more in patients with low tethered cords.

About Authors: Drs. Nathani and Agarwal work for Goyal Hospital and Research Center in Jodhpur, Rajasthan, India. Their work does not have any support for the work in the form of grants, equipments or drugs.

References:

1 . Renshaw T.S. Sacral Agenesis. The Pediatric Spine -Principles and Practice. 1:2214,1994, Raven Press, NewYork

2. Phillips W.A. Sacral Agenesis. Spine - Principles andPractice. 1:2214,1994, Raven Press, New York

3. A.James Barkovich, Congenital Anomalies of the spine.In: Paediatric Neuroimaging ,Vol 2 ,3rd edition, Lippincott Williams & Wilkins,2000 (650-651),

4. Phyllis Glanc et al, The Fetal Musculoskeletal System. In : Carol M. Rumack's Diagnostic Ultrasound;Vol 2, 2nd edition, Mosby. (1224).

5. Beryl R. Benacerraf,Caudal Regression Syndrome and Sirenomelia; in Ultrasound of Fetal Syndromes,edition 1998, (page 250-254); Churchill Livingstone,Philadelphia.

6. Thomas.P.Naidich,Susan I.Blaser,Bradley M.Delman,Congenital Anomalies of Spine and Spinal Cord. In:Scott W. Atlas, Magnetic Resonance Imaging of the Brain and Spine(vol 1) 3rd edition. Philadelphia: Lippincott Williams & Wilkins,2002;( 1589-1593)

7. Renshaw, T. S., 1978. Sacral agenesis: a classification and review of twenty-two cases. Journal of Bone and Joint Surgery, 60A, 373-383.

Non Accidental Injury (NAI): Rib Fractures

Chest radiography of a 2-month-old baby shows multiple bilateral rib fractures of different ages. Left-sided rib fractures (arrowheads) appear to have callus formation, while the right sided fractures (arrows) do not. Note right pleural effusion/thickening laterally.

Facts: Fractures in Non-Accidental Injury

• Second most common findings of child abuse after dermatologic findings (bruises, contusions, burns)
• Can be found throughout the whole skeleton
• Likely multiple and in diverse stages of healing
• Long bone fractures are the most common, with some oblique or spiral components (due to torsion force)
• Classic metaphyseal lesions and location of fractures (ie, posterior rib fractures) are more suspicious than others

Rib Fractures in NAI

• Highly predictive of child abuse in the absence of accidental trauma or certain skeletal diseases (e.g., osteogenesis imperfecta), particularly in children less than 3 years old
• In children with rib fractures, the likelihood of NAI decreases with increasing age
• Multiple rib fractures are more likely to be seen in NAI compared to single fractures
• NAI is more likely in the presence of posterior rib fracture

Our case: non-accidental injury with multiple rib fractures in various stages of healing

Reference:

Medina LS, Applegate KE, Blackmore CC. Evidence-based Imaging in Pediatrics, 2010.

Infantile Hypertrophic Pyloric Stenosis

Longitudinal scan of the stomach (as labeled) shows a thickened (5 mm) wall of the pylorus and elongation of the pyloric canal. Labe

Facts: Pyloric Stenosis

• Most common surgical etiology for young infant presenting emergently with nonbillous vomiting
• Incidence: 2 to 5 of every 1,000 infants
• Multifactorial etiology: genetic, biochemical and environmental association
• Hypertrophy of the pyloric muscle, leading to gastric outlet obstruction (vomiting, dehydration, poor weight gain and hypochloremic metabolic alkalosis)
• Average age of presentation = 3 weeks old (rare before 1 week, or after 3-4 months)

Imaging

• US is now the imaging modality of choice for diagnosis of this condition. It can directly show the pyloric muscle
• Elongation of the pyloric canal
• Persistent spasm of pyloric canal with little, if any, fluid passing into the duodenum
• Persistent thickening of the circular muscle in the canal
• Pyloric muscle thickness (one wall) greater than 4 mm, or pyloric length greater than 16 mm (cutoff values vary depending on the sensitivity, specificity needed to make the diagnosis)
• Imaging differential diagnosis is pylorospasm. In pylorospasm, there is usually no thickening of the pylorus (can be up to 2-3 mm) and when visualized in real time the pylorus can open
• If ultrasound is negative, UGI series or nuclear medicine to evaluate for reflux may be necessary.

References:

1. Swischuk LE. Imaging of the newborn, infant and young child, 5th edition.

2. Hernanz-Schulman M, Berch BR, Neblett WW. Imaging of infantile hypertrophic pyloric stenosis (IHPS). Evidence-based Imaging in Pediatrics 2010; 5:447-457.

Mesoblastic Nephroma

A 10-day-old infant presented with hematuria. Multiple CT images show a large heterogeneous mass originating from the lower pole of the right kidney (cortical beak sign noted, pink arrow). The mass extends into the right renal pelvis and causes mild hydronephrosis.

Facts

• Synonyms: mesoblastic nephroma, leiomyomatous hamartoma, mesenchymal hamartoma, renal fibroma, Bolande tumor.
• It is the most common solid renal tumor in the newborn.
• This tumor is believed to arise from metanephric blastema or secondary mesenchyme.
• Patients usually presents with a palpable flank mass.
• Prognosis is excellent with nephrectomy and wide resection

Imaging Findings

• Large solid intrarenal mass, which typically involves or extends to the renal sinus.
• Hemorrhage, necrosis or cystic portions are uncommon.

Table: Age Presentation of Renal Tumors in Children

References

1. Donnelly LF. Diagnostic imaging pediatrics. Amirsys. Manitoba. 2005.

2. Lowe LH, Isuani BH, Heller RM, Stein SM, Johnson JE, Navarro OM, Hernanz-Schulman M. Pediatric renal masses: Wilms tumor and beyond. Pediatric renal masses: Wilms tumor and beyond. Radiographics. 2000; 20:1585-603.

Hematosalpinx

Fig.1: Sagittal US image of the pelvis of a 13-year-old girl presenting with acute pelvic pain shows multiple cystic lesions (arrows) behind the uterus (U). These cystic structures have peculiar frondlike structures internally suggesting that they represent a dilated fallopian tube.
Fig. 2: Sagittal T2W MR image confirms the presence of dilated fallopian tube with fluid-fluid levels, suggesting hematosalpinx.

Facts: What Causes Hematosalpinx?

• Tubal pregnancy (most common)
• Endometriosis
• Fallopian tube cancer
• Obstructed vagina resulting in menstrual blood backflow into fallopian tubes

Facts: Isolated Tubal Torsion

• Very rare entity causing lower abdominal pain
• Usually occurs in reproductive age
• Diagnosis rarely made preoperatively
• Imaging findings are adnexal cystic mass, hydrosalpinx, hematosalpinx
• Twisted fallopian tube, if visualized, is a specific sign for tubal torsion. If the ovary is also torsed, the ipsilateral ovary becomes enlarged.

Our case: isolated fallopian tube torsion causing hematosalpinx.

Reference:

1. Park BK, Kim CK, Kim B. Isolated tubal torsion: specific signs on preoperative computed tomography and magnetic resonance imaging. Acta Radiologica 2008;49:233-235.

2. Wikipedia: hematosalpinx

Microcolon with Features of Low Intestinal Obstruction

Barium enema in a 2-day old boy shows diffuse small caliber of the colon (arrows). Retained barium is noted in the stomach from a recent upper GI study (which was normal). Note the presence of air in the rest of the small bowel (tubular lucent areas in the background) indicating that this is a low intestinal obstruction.

Differential Diagnosis: Microcolon with Features of Low Intestinal Obstruction

• Pathology of colon itself: colonic atresia, diffuse Hirschsprung's disease
• Pathology of distal small bowel (no bowel content can pass into colon resulting in small colon caliber): ileal atresia, meconium ileus

Approach: when seen evidence of bowel obstruction in a neonate, one needs to distinguish between high and low intestinal obstruction. High obstruction presents with little amount of gas in the bowel, dilated stomach and/or duodenum. If high obstruction due to midgut volvulus is suspected, upper GI study is the next step. If low obstruction is suspected, barium enema is performed. In this case, we see a lot of bowel gas in the neonate with clinical intestinal obstruction and a barium enema shows diffuse microcolon - the differential diagnoses are either diseases of distal small bowel or of the colon itself.

Our case: distal ileal volvulus with possible meconium ileus producing distal intestinal obstruction and microcolon

Reference:

Davies SG. Chapman & Nakielny's Aids to Radiological Differential Diagnosis, 5th edition, 2009.

Buckle (Torus) Fracture of the Distal Forearm

Radiographs of the wrist of an 11-year-old girl following a fall show a subtle buckle fracture of the distal radius (arrows), clearly visible on the lateral view.

Facts:

• Common locations = wrist and ankle
• 2nd most common fractures in infancy and childhood after epiphyseal-metaphyseal fractures
• Falls on outstretched extremity

Imaging Features:

• Rule -- cortex of a normal bone is always smooth and gently curving (always trace each cortex individually in all available views)
• Buckle fractures can be a focal cortical slope, angle, kink, bump or break
• Usually clearly visible on one view than another
• When healed, sclerosis develops along the fracture line

References:

1. Swischuk LE. Emergency imaging of the acutely ill or injured child. 4th ed, 2000.

2. Swischuk LE. Imaging of the newborn, infant, and young child. 5th ed, 2004.

Step Lightly for Kids

The Alliance for Radiation Safety in Pediatric Imaging has recently offered free materials on dose reduction for interventional radiology procedures, and patient education materials. These have been endorsed by the American College of Radiology (ACR).

"Treat kids with care:

Step lightly on the fluoroscopy pedal.

Stop and child-size the technique.

Consider ultrasound or, when applicable, MRI guidance."

On their website "ImageGently.org", slide presentations, checklists, outlines and patient brochures are available for free download.

Above image from www.ImageGently.org

Fibromatosis Colli of Infancy

Transverse ultrasound images of the right sternocleidomastoic (SCM) muscle and left (symptomatic side) shows diffuse enlargement of the left SCM with mixed echogenicity in a 2-month-old infant.

Facts: Fibromatosis Colli of Infancy

• Abnormal mass-like enlargement of sternocleidomastoic (SCM) muscle
• Born normal but develops SCM mass and/or torticollis within the first 4-8 weeks of life
• Associated with difficult delivery and intrauterine torticollis due to malposition
• Histology: collagen fibers and fibroblasts around atrophied muscle fibers
• Early diagnosis and treatment important because it can result in contracture
• Responds well to physiotherapy

Ultrasound Appearance

• US performed to exclude other diagnosis such as cervical lymphadenopathy, rhabdomyosarcoma, lymphoma, cystic hygroma or branchial cleft cyst
• Mass or fusiform enlargement of the SCM muscle
• Confined to muscle, no adjacent abnormalities of other soft tissues
• Variable echogenicity -- hyperechoic, hypoechoic, or mixed echogenicity

Reference:

Bedi DG, John SD, Swischuk LE. Fibromatosis colli of infancy: variability of sonographic appearance. J Clin Ultrasound 1998;26:345-348.

Double Bubble Sign

Supine abdominal radiograph of a newborn presenting with billous vomiting shows a distended stomach and duodenal air bubbles "double bubble" sign. There is no gas distal to the duodenal bubble. Radiopaque materials overlying the right pelvis are due to soiled diaper.

Double Bubble Sign

• Radiographic signs describing two air-filled structures in the upper abdomen with little or no air distally
• Can be reproduced in upper GI study or ultrasound
• Left-sided bubble = stomach
• Right-sided bubble (usually right of midline) = duodenum
• Most common cause = duodenal atresia

Differential Diagnoses

• Intrinsic cause: duodenal atresia, duodenal stenosis, duodenal web
• Extrinsic cause: annular pancreas, malrotation with obstruction produced by midgut volvulus or by Ladd bands

Main Concern

• Must be differentiated from 'malrotation with obstruction (midgut volvulus)' because this condition requires urgent surgery
• Suspect midgut volvulus if stomach is distended but duodenum is normal or only slightly dilated

Reference:

Traubici J. The double bubble sign. Radiology 2001;220:463-464.

Capitellar Osteochondritis

A 10 yr old gymnast presented with right elbow pain

Timing of ossification center at elbow

CRITOE
Capitellum appears by 8 months

Radial head 3-4 yrs

Internal (medial) epicondyle 5 yrs

Trochlea 7 yrs

Olecranon 9 yrs

External (lateral) epicondyle 11 yrs

Capitellar osteochondritis

• Results from overuse of elbow causing subchondral reactive process and loosening of cartilage and bone
• Usually occurs at anterior surface of capitellum
• Imaging findings show flattening of capitellar surface, or visible lucent zone of defect and sometimes can demonstrate intrarticular fragment of loose bodies.
• Unstable lesions include large size (typically > 1 cm), cystic lesion beneath the osteochondrotic site, containing loose granulation tissue or loose fragement, fluid insinuating beneath the fragment

Reference Elbow In: Stoller DW, Tirman PFJ, Bredella MA . in Diagnostic Imaging: Orthopaedics. Amirsys.2003.

Subependymal Giant Cell Astrocytoma

Fig 1&2: Axial and coronal MR images (contrast enhanced T1WI) show an enhancing mass in the left caudothalamic groove in a patient with known tuberous sclerosis. Given the size and enhancement on this initial scan, a concern of SGCA should be raised.

Subependymal giant cell astrocytoma (SGCA)

• 1 in 10 individuals with TSC
• Arises from subependymal nodules
• Can result in ventricular obstruction
  
• It is recommended by the National Tuberous Sclerosis Association that brain imaging obtainend at every 1-3 years in children, up to the age of 21 years, to detect giant cell astrocytoma

Imaging Appearances That May Suggest SGCA

• Serial growth (best imaging predictor)
• Hydrocephalus
  
• Contrast enhancement
• Size >1 cm

Reference:
Goh S, Butler W, Thiele EA. Subependymal giant cell tumors in tuberous sclerosis complex. Neurology 2004;63:1457-1461.

Torus (Buckle) Fracture

Fig: Forearm radiograph shows a fracture as bulged cortex at the distal end of the radius. This is a classic torus (buckle) fracture.

Facts

• Axial loading on extremity with/without other forces (i.e. varus, valgus, hyperextension or hyperflexion)
• Failure of cortex on the compression side, resulting in fracture
  
• Torus (buckle) fracture of distal radius and ulna is most common fracture in lower forearm of young children
• Two appearances: 1) classic buckle fracture -- cortex bulges outward, 2) angled buckle fracture -- cortex angles inward (the second type is more difficult to appreciate)

Reference:
Jadhav SP, Swischuk LE. Commonly missed subtle skeletal injuries in children: a pictorial review. Emerg Radiol 2008 (November)

A child with scalp mass

Sagittal T1W image demonstrates a parieto-occipital scalp mass with a band of soft tissue anterosuperior to the mass running through a small skull defect which appears to connect to the intracranial compartment.

Sagittal T2W image demonstrates a persistent embryonic falcine sinus/vertically oriented straight sinus and prominence of the superior cerebellar cistern.

The mass shows a thin peripheral enhancement as well as enhancement of the soft tissue band.

Diagnosis:

Atretic (en)cephalocele

Facts:

- A midline mass typically parietal in location, occasionally seen in occipital region.

- Contain meninges and neural rests. A fibrous stalk connects the lesion to the dura.

- A vertically positioned straight sinus/persistent embryonic falcine sinus commonly
associated with these malformations. Anomalies of the tentorial incisura and superior sagittal
sinus have also been reported.
- Associated intracranial anomalies are variable, and some children may have normal clinical outcomes with no associated intracranial anomalies

References:

AJNR Am J Neuroradiol 19:791–795, April 1998
RadioGraphics 2004; 24:1655–1674