Rhabdomyosarcomas of the biliary tract are rare tumors, usually identified in children, with a very poor prognosis. They are usually grouped under botryoid rhabdomyosarcomas.
For a general discussion of this type of tumor, please refer to the article on rhabdomyosarcomas.
Rhabdomyosarcomas of the head and neck represent a large proportion (~40%) of all rhabdomyosarcomas and are the most common soft tissue sarcomas of the head and neck. For a general discussion of this tumor, please refer to rhabdomyosarcoma.
There are usually of the embryonal in cell ...
Rheumatic fever is an illness caused by an immunological reaction following group A streptococcal infection.
Risk factors include:
children and adolescents aged 5 to 15 years
developing nations where antibiotic prescription is low 1
Rhinoliths, also known as nasal calculi, are uncommon lesions that result from a chronic inflammatory response to complete or partial mineralized encrustation of intranasal foreign bodies. They are most commonly seen in children and cognitively impaired adults who insert foreign bodies into thei...
Rhombencephalosynapsis is a congenital abnormality of the cerebellum characterized by the vermis absence and continuity of the cerebellar hemispheres, dentate nuclei, and superior cerebellar peduncles. It either occurs as an isolated anomaly (rare) or as part of wider cerebral malformation and i...
Rib fractures in non-accidental injury are a relatively common mode of presentation in inflicted non-accidental injury.
Rib fractures can be separated based on their location:
Posterior rib fractures are most commonly the result of an anteroposterior...
Rickets, less commonly known as rachitis, refers to deficient mineralization of the growth plate in the pediatric population. In contrast, osteomalacia refers to deficient mineralization of the bone matrix, which co-occurs with rickets but can also occur even after growth plate closure, in adult...
Right middle lobe syndrome refers to chronic right middle lobe collapse, without an obstructing lesion. It is usually with associated bronchiectasis.
Right middle lobe syndrome is usually encountered in older adults, with a predilection for women (see Lady Windermere syndrome). I...
A useful mnemonic to remember the differential diagnoses associated with right-to-left cardiovascular shunts is:
1: a combination vessel; truncus arteriosus
2: number of arteries involved; transposition of the great arteries
3: "tri-" means 3, the number of leaflets involved; t...
Ritscher-Schinzel syndrome (RTSC), also known as 3C (cranio-cerebello-cardiac) syndrome, is a rare entity with a variable spectrum of CNS (primarily cerebellar), craniofacial, and congenital heart defects.
Roberts syndrome, also known as Roberts-SC phocomelia syndrome, pseudothalidomide syndrome, or Appelt-Gerken-Lenz syndrome, is a rare congenital malformation syndrome.
intrauterine growth restriction
postnatal growth retardation
failure to thrive
Robin sequence, also called Pierre Robin syndrome or Pierre Robin anamaloid, is a congenital condition characterized by facial abnormalities. Its etiology has no genetic base, but rather, is reliant on a sequence of events, one following the other.
Robin sequence is the preferred t...
Round pneumonia is a type of pneumonia usually only seen in pediatric patients. They are well defined, rounded opacities that represent regions of infected consolidation.
The mean age of patients with round pneumonia is 5 years and 90% of patients who present with round pneumonia ...
Sacral agenesis (also considered as part of the caudal regression syndrome) is a rare and severe sacral developmental abnormality.
In normal pregnancy, the incidence is between 0.005 and 0.1%. However, in fetuses with diabetic mothers, the incidence rises to 0.2%. Of those with th...
Sacral dimples are a clinical and radiological feature that is associated with occult spinal dysraphism (e.g. tethered cord syndrome) but are more frequently a non-significant isolated finding.
Common in healthy children (~5%) 1.
Simple sacral dimples have the followin...
Sacrococcygeal teratoma (SCT) refers to a teratoma arising in the sacrococcygeal region. The coccyx is almost always involved 6.
It is the commonest congenital tumor in the fetus 11 and neonate 3. The incidence is estimated at ~1:35000-40000. There is recognized female predilectio...
SADDAN syndrome is an acronym for severe achondroplasia with developmental delay and acanthosis nigricans. It is an extremely rare condition, and as the name states, comprises a combination of skeletal, brain and cutaneous anomalies.
The syndrome results from a mutation in ...
Saethre-Chotzen syndrome (also known as type III acrocephalosyndactyly) is characterized by limb and skull abnormalities.
It is the most common craniosynostosis syndrome and affects 1:25 - 50,000 individuals.
Males and females are equally affected.
The Sakati-Nyhan syndrome, also known as Sakati-Nyhan-Tisdale syndrome or acrocephalosyndactly type III, is an extremely rare type of acrocephalopolysyndactyly.
Its main features include:
congenital limb abnormalities
congenital heart defects
History and etymology
Salla disease, also known as Finnish type sialuria, is a rare autosomal recessive disease that primarily affects the central nervous system. It is considered the mildest form of free sialic acid storage disorder.
Neurological symptoms related to this rare disease are usua...
The Salter-Harris classification was proposed by Salter and Harris in 1963 1 and at the time of writing (June 2016) remains the most widely used system for describing physeal fractures.
Conveniently the Salter-Harris types can be remembered by the mnemonic SALTR.
Useful mnemonics for remembering the Salter-Harris classification system are:
Fortunately, this is also the order of prognosis (from best to worse)
S: slipped (type I)
A: above or away from joint (type II)
L: lower (type III)
T: through or transverse or toget...
Salter-Harris type I fractures are relatively uncommon injuries that occur in children. Salter-Harris fractures are injuries where a fracture of the metaphysis or epiphysis extends through the physis. Not all fractures that extend to the growth plate are Salter-Harris fractures.
Salter-Harris type II fractures are the most common type of physeal fractures that occur in children. There is a fracture that extends through the physis and into a portion of the metaphysis. A triangular metaphyseal fragment, otherwise known as the Thurston Holland fragment, will be left intact...
Salter-Harris type III fractures are an uncommon, intraarticular fracture physeal fractures that occur in children.
The fracture line is often obliquely oriented through the epiphysis to the physis where it will take a horizontal orientation extending to the edge of the physis.
The Salter-Thompson classification of Perthes disease simplifies the Catterall classification into two groups. Based on the radiographic crescent sign, we can distinguish:
group A: including Catteral groups I and II, where the crescent sign involves less than 50% of the femoral head
group B: i...
Sanjad Sakati syndrome (SSS) is also known as hypoparathyroidism - retardation - dysmorphism (HRD). It is a rare autosomal recessive genetic disorder.
Exclusively found in people of Arabian origin. There is an equal distribution in both sexes.
Gene of the sy...
A scalp hematoma usually occurs following an injury at delivery although they are commonly seen with head trauma.
There are three types of hematoma, which are defined by their location within the scalp, particular their location as related to the galea aponeurosis and skull peri...
Scaphocephaly (also known as dolichocephaly) is the most common form of craniosynostosis, where premature closure of the sagittal suture results in an impediment to the lateral growth of the skull while anteroposterior growth continues, producing a narrow and elongated skull. Causes are primary,...
The Scham sign of slipped capital femoral epiphysis is one of the subtle signs that may be seen on the AP view of an adolescent hip with early slip.
In the normal adolescent hip, an intraarticular portion of the diaphysis of the collum overlies the posterior wall of the acetabulum inferiomedial...
Schindler disease is a rare lysosomal storage disorder characterized by deficiency of alpha-N-acetylgalactosaminidase (alpha-NAGA or alpha-galactosidase B).
It is a rare disease with autosomal recessive inheritance.
Age and severity of presentation depends ...
Schizencephaly is a rare cortical malformation that manifests as a grey matter lined cleft extending from the ependyma to the pia mater.
Some authors do not use the term schizencephaly, preferring to group these disorders under the blanket term of porencephaly. For the purpose of t...
Scimitar syndrome, also known as hypogenetic lung syndrome, is characterized by a hypoplastic lung that is drained by an anomalous pulmonary vein into the systemic venous system. It is a type of partial anomalous pulmonary venous return and is one of the several findings in congenital pulmonary ...
Sclerosing bone dysplasias comprise a heterogeneous group of disorders (skeletal dysplasias) united by the presence of sclerosis of one form or another. Some of these entities are thought to be related (e.g. osteopoikilosis, melorheostosis and Buschke-Ollendorff syndrome) 1.
Scoliosis is defined as an abnormal lateral curvature of the spine. It is quite common in young individuals and is often idiopathic and asymptomatic. In some cases, however, it is the result of underlying structural or neurological abnormalities.
By definition, scoliosis is any lat...
Seckel syndrome is an autosomal recessive congenital dwarfing disorder.
The estimated incidence is ~1:10,000. There is no recognized gender predilection.
It is clinically characterized by many features including:
intrauterine growth restriction
Self‐limiting sternal tumors of childhood (SELCTOC) are rare, self-limiting, dumbbell-shaped chest wall tumor found in young children.
Median age is 16 months (range 7-50 months).
The pathology is not clearly defined, but often shows aspecific inflammation.
The Senning repair is one of two "atrial switch" procedures used to functionally correct transposition of the great arteries (the other being the Mustard repair).
The two repairs share a similar fundamental principle. Systemic blood flow is redirected away from the right ventricle and toward t...
Septo-optic dysplasia (SOD), also known as de Morsier syndrome, is a condition characterized by optic nerve hypoplasia and absence of the septum pellucidum and, in two-thirds of patients hypothalamic-pituitary dysfunction. It is best thought of as being part of the holoprosencephaly spectrum (se...
Sexual differentiation refers to the embryological development of male and female phenotypes. Unlike sexual genotype which is determined at the time of fertilisation, the male and female phenotypes do not begin to differentiate substantially until the seventh week of gestation.
Shone syndrome, also known as Shone complex, is a rare syndrome characterized by left-sided, obstructive congenital heart defects.
Shone syndrome is thought to be very rare, accounting for less than 1% of all congenital heart disease 1.
Patients, usually ne...
Short gut syndrome also is known as short bowel syndrome, is a kind of malabsorption disorder due to functional loss or loss of a portion of the small or large intestine during congenital deficiency (necrotizing enterocolitis) or acquired conditions and It is classified as a rare disease by the ...
Short limb skeletal dysplasias are skeletal dysplasias which are characterized by limb shortening
Rhizomelic (proximal limb shortening)
particularly type II
SHORT syndrome refers to an acronym which primarily comprises of the following features:
S: short stature
H: hyperextensibility of joints and/or inguinal hernia
O: ocular depression
R: Rieger anomaly
T: teething delay
In a addition to these there can be numerous associated minor features w...
The shoulder sign of pyloric stenosis is seen during barium examination and refers to the bulging of the hypertrophied pyloric muscle into the lumen of the antrum.
It is closely related to the cervix sign of pyloric stenosis.
cervix sign of pyloric stenosis
target sign of pyloric s...
The Shwachman-Diamond syndrome (SDS) or Shwachman-Bodian-Diamond syndrome (SBDS) is a rare autosomal recessive disorder characterized by 1 :
exocrine pancreatic insufficiency
bone marrow hypoplasia (cyclic neutropenia)
Patients with Shwachman-...
Skeletal manifestations of sickle cell disease result from three interconnected sequelae of sickle cell disease 5:
vaso-occlusive crises resulting in bone infarcts and subperiosteal hemorrhages
chronic anemia resulting in expansion of the medullary spaces
These, in turn, can predi...
Simple pancreatic cysts, also known as true epithelial cysts or retention cysts, are unilocular cysts within the pancreas, lined by a monolayer of epithelium, which lack communication with the pancreatic ducts 1,5. In contradistinction to other solid viscera, simple cysts in the pancreas are a r...
Sincipital encephaloceles are congenital herniations of cerebral parenchyma through a cranial defect. There are three main types 1,2:
frontonasal encephalocele (~50%): more common in Asia and Latin America 4
naso-ethmoidal encephalocele (30%): more common in North America 4
Sinding-Larsen-Johansson disease (SLJ), also known as Sinding-Larsen disease or Larsen-Johansson syndrome, affects the proximal end of the patellar tendon as it inserts into the inferior pole of the patella. It represents a chronic traction injury of the immature osteotendinous junction. It is a...
Single umbilical artery (SUA) results when there is a congenital absence of either the right or left umbilical artery. In the usual situation, there are paired umbilical arteries. For unknown reasons, the absence of the left umbilical artery is much more common (~70%).
Sinus pericranii is a cranial venous anomaly in which there is an abnormal communication between intracranial dural sinuses and extracranial venous structures, usually via an emissary transosseous vein.
It is considered a type of low flow vascular malformation. It occurs in close communication ...
Situs classification (plural: sitūs) can be a daunting topic, but it falls into three main groups:
situs solitus: the normal configuration of thoracic and abdominal organs
situs inversus: mirror image of the normal configuration
situs ambiguus (heterotaxy): an intermediate configuration with ...
Situs solitus (rare plural: sitūs soliti) refers to the normal position of the thoracic and abdominal organs.
On plain radiograph, careful attention should be directed at the location of the aortic arch, gastric fundus, cardiac apex, pulmonary fissures a...
Sjögren-Larsson syndrome is a rare inherited autosomal recessive neurocutaneous syndrome and leukodystrophy characterized by the clinical triad of ichthyosis, intellectual disability, and spastic diplegia or tetraplegia.
Although considered very rare, the exact prevalence is not k...
Skeletal dysplasia (also known as osteochondrodysplasia) refers to any abnormality in bone formation. There is a very wide clinicopathological spectrum and any part of the skeleton can be affected.
The overall prevalence is estimated at ~2 per 10,000 live births 3.
The presence of intramuscular edema (increased high T2/STIR signal) on MRI carries an extremely broad differential. They include:
effects of direct injury or tear
denervation injury: denervation changes in muscles
early myositis ossificans
A skeletal survey in NAI is a defined set of images that are obtained to assess the majority of the bones in the child. Referral for a skeletal survey in this context will usually come from a member of the child protection team and there should be a thorough discussion about their concerns prior...
Skull fracture in non-accidental injury is the result of abusive impact head trauma. However, skull fractures do occur in children as the result of accidental head injury and it is important for the radiologist to understand what features make a non-accidental etiology more likely.
Slipped upper femoral epiphysis (SUFE), also known as a slipped capital femoral epiphysis (SCFE), (plural: epiphyses) is a relatively common condition affecting the physis of the proximal femur in adolescents. It is one of the commonest hip abnormalities in adolescence and is bilateral in ~20% o...
Grading of SUFE (slipped upper femoral epiphysis) can be made on both AP and true lateral projections.
On an AP radiograph a line along the superior margin of the femoral neck (line of Klein) should intersect the lateral corner of the epiphysis.
As the epiphysis slips, the metaphysis can be d...
This is a basic article for medical students and other non-radiologists
Slipped upper femoral epiphysis (SUFE), also known as a slipped capital femoral epiphysis (SCFE), is a relatively common condition affecting the physis of the proximal femur in adolescents. It is one of commonest hip abnor...
Small bowel atresia corresponds to malformations where there is a narrowing or absence of a portion of the small bowel, which includes:
A number of tumors share similar histology, composed of relatively uniform primitive small round blue cells. They also share many demographic, radiographic and clinical similarities. They include:
peripheral primitive neuroectodermal tumor (pPNET)
Smith-Magenis Syndrome (SMS) is a rare genetic syndrome which results from an interstitial deletion in chromosome 17p11.2.
The condition is known by several other names which are all similar variants related to its underlying karyotype: 17p deletion syndrome, 17p11.2 monosomy, chro...
Snowman sign, also sometimes referred to as a figure of 8 sign or dumbell sign, is a radiologic sign related to conditions that have a shape which resembles a snowman. This include:
snowman sign (total anomalous pulmonary venous return) 1
snowman sign (pituitary macroadenoma) 2,3
Snowman sign refers to the configuration of the heart and the superior mediastinal borders resembling a snowman. This is seen in total anomalous pulmonary venous return (TAPVR) type I (supracardiac type). It is also referred to as the figure of 8 sign.
It is an abnormality of the fetal circulat...
The differential diagnosis of a solitary sclerotic bone lesion is heavily influenced by the age of the patient, and includes:
solitary either because no others are present or no others have been imaged
enostosis (bone island)
The sphenoidal or anterolateral fontanelles (or fontanels) are paired bilateral soft membranous gaps at the junction of the coronal, sphenofrontal, sphenoparietal, sphenosquamosal, and squamosal sutures. Each mastoid fontanelle persists until approximately six months after birth, after which it ...
Spinal dysraphisms refer to a broad group of malformations affecting the spine and/or surrounding structures in the dorsum of the embryo. They are a form of neural tube defect.
The neural tube is formed by the lengthwise closure of the neural plate, in the dorsum of the embryo.
Spinal muscular atrophy is a type of congenital neuromuscular disease affecting anterior horn cells of the brainstem and spinal cord.
This disorder affects 1 in 6000-10000 infants 1.
Spinal muscular atrophy typically affects infants and young children, pres...
Spinal neurenteric cysts are a rare type of foregut duplication cyst, accounting for ~1% of all spinal cord tumors. They are usually classified as spinal or intracranial and are associated with vertebral or CNS abnormalities respectively.
Neurenteric cysts result from incomplete res...
The spleen size varies with a child's age.
The three numbers below represent the 10th percentile, median, and 90th percentile for the long axis of the spleen (cm)
0-3 months: (3.3, 4.5, 5.8 cm)
3-6 months: (4.9, 5.3, 6.4 cm)
6-12 months: (5.2, 6.2, 6.8 cm)
1-2 years: (5.4, 6.9, 7.5 cm)
Spondylocostal dysostosis (SCDO) is a rare condition characterized by short-trunk dwarfism secondary to developmental anomalies of the vertebrae and ribs. Previously the condition Jarcho-Levin syndrome (also known as spondylothoracic dysostosis) was grouped together with spondylocostal dysostosi...
Spondyloepiphyseal dysplasia is a type of skeletal dysplasia that mainly involves the spine and proximal epiphyseal centers.
short trunk with protruding abdomen
craniovertebral junction stenosis
Sprengel deformity, or congenital elevation of the scapula, is a complex deformity of the shoulder and is the most common congenital shoulder abnormality. An initial diagnosis can often be made on radiography, but CT or MRI is often necessary to evaluate the details of the abnormality.
The Srb anomaly describes an anatomic variant of the ribs, in which there is partial to complete bony ankylosis of the first and second ribs.
Strawberry skull refers to the shape of the head on an antenatal ultrasound.
In general, strawberry skull is considered one of the non-specific 'soft markers' for abnormal fetal development. It is considered more closely associated with trisomy 18 (Edward syndrome).
Brain ischemia/infarction in children and young adults can result from several causes.
cyanotic heart disease
mitral valve prolapse
Sturge-Weber syndrome, or encephalotrigeminal angiomatosis, is a phakomatosis characterized by facial port wine stains and pial angiomas.
It is part of a wide spectrum of possible phenotypes included in the craniofacial arteriovenous metameric syndrome (CAMS).
Subacute sclerosing panencephalitis (SSPE), also known as Dawson disease, is a rare chronic, progressive and fatal encephalitis that affects primarily children and young adults, caused by a persistent infection of immune resistant measles virus.
1 in 100,000 people infected with ...
Subcortical leukomalacia corresponds to a continuous disease spectrum of periventricular leukomalacia (PVL) as the vascular border zones shift towards the periphery as the brain further matures. For this reason white matter lesions move from the periventricular to the subcortical zone.
Subependymal hamartomas are seen in patients with tuberous sclerosis. They are located along the ventricles and are mostly asymptomatic. As with other hamartomas, they grow at the same rate as the surrounding tissues.
On imaging, they appear as small intraventricular masses, smaller than 1 cm, ...
Subgaleal hematoma describes scalp bleeding in the potential space between the periosteum and the galea aponeurosis. It is a rare but possibly lethal emergency.
Moderate to severe presentations occur in 1.5 of 10,000 live births. It most commonly occurs after vacuum-assisted and f...
Subpial hemorrhage is a rare form of extra-axial intracranial hemorrhage defined as hemorrhage between the cortical surface and the pia mater. It is an entity that is generally difficult to distinguish from subarachnoid hemorrhage.
Subpial hemorrhage has been typically described i...
The sunset eye sign (also known as the setting sun phenomenon) is a clinical phenomenon encountered in infants and young children with raised intracranial pressure (seen in up to 40% of children with obstructive hydrocephalus and 13% of children with shunt dysfunction 1).
It consists of an up-...
Supracondylar humeral fractures, often simply referred to as supracondylar fractures, are a classic pediatric injury which require vigilance as imaging findings can be subtle.
Simple supracondylar fractures are typically seen in younger children, and are uncommon in adults; 90% ar...
A mnemonic for surgically-created cardiac shunts for congenital heart disease is:
Great Flow Really Would Be Perfect
The mnemonic is ordered by the position of the shunt antegrade to normal blood flow through the heart, proceeding from the systemic venous system into the right heart, and then...
Syndactyly (plural: syndactylies) refers to a congenital fusion of two or more digits. It may be confined to soft tissue (soft tissue syndactyly/simple syndactyly) or may involve bone (bony syndactyly/complex syndactyly).
The overall estimated incidence is at ~1 per 2,500 to 5,000...
Synovial hemangiomas are rare benign vascular malformations that occur in relation to the joint. It is sometimes considered a subtype of soft tissue hemangiomas.
The lesions typically present in children and young adults. Occasionally patients can have recurrent haemarthroses 8.
Syphilis is the result of infection with the gram negative spirochete Treponema pallidum, subspecies pallidum. It results in a heterogeneous spectrum of disease with many systems that can potentially be involved, which are discussed separately.
Despite the discovery of penicillin...
The tadpole sign, also known as the lollipop sign, refers to a characteristic morphology of post-traumatic bridging vein thrombosis with a rounded "head" and a tapering "tail". The finding demonstrates a high specificity for abusive head trauma, a sub-type of non-accidental injury, and should wa...
The Takeuchi procedure refers to a direct anastomosis of the anomalous left coronary artery from the pulmonary artery directly to the aorta was described in the 1970s and currently remains the procedure of choice.
An intrapulmonary aortocoronary tunnel or baffle was performed by Takeuchi prior ...