Pseudocysts of the germinal matrix can be present at birth in both pre-term and full-term infants and may be due to a variety of pathologic disorders, frequently occur following hemorrhage, but they are also found incidentally in otherwise normal infants.
They are defined as pseudocysts because...
A pseudosinus tract is a normal fibrous cord extending from the coccyx to an overlying sacral dimple. These have no associated mass and contain no fluid (if CSF drainage is occurring via the sacral dimple, then a true dorsal dermal sinus should be considered).
Pseudosubluxation of the cervical spine is the physiological anterior displacement of C2 on C3 in children. It is common in children <7 years, and less often present in older children. Less often it is seen at C3 on C4. It is more pronounced in flexion and is of clinical significance as it can b...
Pulled elbow (also known as nursemaid's elbow) is a subluxation of the radial head into the annular ligament, which usually spontaneously or easily reduces and rarely demonstrates abnormal radiographic features. It should be distinguished from dislocation of the radial head.
Pulmonary aplasia is a rare congenital pathology in which there is unilateral or bilateral absence of lung tissue. It is distinguished from pulmonary agenesis, although similar, the main difference being that there is a short-blind ending bronchus in aplasia 3.
It is usually unilateral, as bila...
Pulmonary artery atresia (or sometimes known as pulmonary atresia) is a congenital cardiovascular anomaly in which there is complete disruption between the right ventricular outflow tract (RVOT) and the pulmonary trunk.
The estimated incidence is 1 in 10,000 births.
Pulmonary atresia with intact interventricular septum (PA-IVS) is a subtype of pulmonary atresia that presents as cyanotic congenital heart disease.
PA-IVS is the combination of obstruction of the pulmonary outflow tract from pulmonary valve atresia without a ventricular septal defe...
Pulmonary hypoplasia (PH) refers to deficient or incomplete development of parts of the lung. It can develop as a result of a number of other in utero anomalies.
The true prevalence is not well known (1.4% of all births according to Knox et al. 13), but in cases of premature ruptu...
Pulmonary interstitial emphysema (PIE) refers to the abnormal location of air within the pulmonary interstitium and lymphatics usually due to positive pressure ventilation. It typically results from rupture of overdistended alveoli following barotrauma in infants with hyaline membrane disease. I...
Pulmonary lymphangiectasia (PL) refers to a rare, fatal congenital abnormality of the lungs characterized by grossly dilated lymphatic channels in the sub pleural, interlobar, perivascular and peribronchial areas 3.
It is divided into two main types 1:
cardiac-associated lymphangiectasia (seco...
Pulmonary plethora is a term used to describe the appearances of increased pulmonary perfusion on chest radiographs. It is commonly used in pediatric radiology.
Usually a left-to-right shunt of 2:1 is required for pulmonary plethora to occur 2,3. Increased pulmonary perfusion occurs...
Pulmonary sequestration, also called accessory lung, refers to the aberrant formation of segmental lung tissue that has no connection with the bronchial tree or pulmonary arteries. It is a bronchopulmonary foregut malformation (BPFM).
There are two types:
intralobar sequestration (ILS)
Extralobar pulmonary sequestration (ELS) is a subtype of pulmonary sequestration, the other type being intralobar pulmonary sequestration (ILS).
It is usually encountered in infants, most being diagnosed before six months. It is more common in male (M:F 4:1).
Intralobar pulmonary sequestration (ILS) is a subtype of pulmonary sequestration.
Patients usually present before the third decade with recurrent infection.
It is the commoner type of pulmonary sequestration (four times commoner than extralobar sequestration),...
Pulmonary valve stenosis, or pulmonic valve stenosis, is a valvulopathy that describes narrowing of the opening of the pulmonary valve between the pulmonary trunk and the right ventricle.
Pulmonary stenosis is nearly always (95%) congenital, and therefore primarily affects the ped...
Pyknodysostosis, also known as osteopetrosis acro-osteolytica or Toulouse-Lautrec syndrome, is a rare autosomal recessive bone dysplasia, characterized by osteosclerosis and short stature.
Patients present in early childhood with:
short stature, particularly limbs
Hypertrophic pyloric stenosis (HPS) refers to the idiopathic thickening of gastric pyloric musculature which then results in progressive gastric outlet obstruction.
Pyloric stenosis is relatively common, with an incidence of approximately 2-5 per 1,000 births, and has a male pred...
Raccoon eyes sign (or panda eyes in the UK and Ireland) is due to periorbital ecchymosis and is specific for base of skull fracture of the anterior cranial fossa.
However it is not pathognomonic for trauma, and there are several rare causes described, including metastatic neuroblastoma, Kaposi ...
Rachipagus twins are an extremely rare type of conjoined twins. They are joined in the dorsal aspect and face away from each other.
Fusion of the occiput with varying segments of the vertebral column may occur, resulting in the sharing of the spinal cords. The fusion terminates above the sacrum...
Rachitic rosary refers to expansion of the anterior rib ends at the costochondral junctions and is most frequently seen in rickets as nodularity at the costochondral junctions.
Other causes of this appearance include:
the costochondral junction is more angula...
Radial head dislocation occurs when the radial head is displaced from its normal articulation with the ulna and the humerus.
The dislocation may be acquired or congenital (see the separate article on congenital radial head dislocation). Additionally, radial head dislocation should be distinguis...
Radial ray anomalies comprise of a large spectrum of upper limb anomalies which range from partial (radial hypoplasia) to a complete (radial aplasia) deficiency of the radius with or without accompanying deficiency of the thumb bones.
They can be associated with a numbe...
The radiocapitellar line is one of the key lines used to assess alignment on the elbow radiograph. It is particularly useful in the pediatric setting.
A line drawn down the neck of the radius should intersect the capitellum. It is important to ensure that you draw the line down the ra...
Raghib syndrome is a rare developmental complex. It consists of:
persistence of the left superior vena cava
coronary sinus ostial atresia
atrial septal defect
It has also been associated with other congenital malformations including ventricular septal defects, enlargement of the tricuspid an...
Raine syndrome, also known as lethal osteosclerotic bone dysplasia, is a very rare genetic disorder. Infants with this syndrome present with numerous characteristic craniofacial features as well as cerebral calcifications. Many individuals with this disorder are stillborn or die as neonates 4.
Rasmussen encephalitis, also known as chronic focal encephalitis, is a chronic inflammatory disease of unknown origin, usually affecting one brain hemisphere.
It is not to be confused with a Rasmussen aneurysm.
Most cases (85% cases) occur in children under the age of 10 years 1....
RASopathies are a class of developmental disorders caused by germline mutations in genes that encode for components or regulators of the Ras/mitogen-activated protein kinase (MAPK) pathway.
As a group, RASopathies represent one of the most common malformation syndromes, with an in...
The rectosigmoid ratio is a measurement of the diameter of the rectum divided by that of the sigmoid colon during contrast enema. It is of particular use in the diagnosis of Hirschsprung disease.
Normal children have a rectum that is larger than the sigmoid (i.e. rectosigmoid ratio >1). In fact...
Renal agenesis refers to a congenital absence of one or both kidneys. If bilateral (traditionally known as the classic Potter syndrome) the condition is fatal, whereas if unilateral, patients can have a normal life expectancy.
Unilateral renal agenesis affects approximately 1 in ...
Renal replacement therapy (RRT) (also called renal dialysis or just dialysis) is used to supplement renal function in patients with either end-stage chronic kidney disease or medically-refractory acute renal impairment.
Haemodialysis refers to the diffusion of solutes in solution across...
Renal tumors (for the purposes of this article taken to broadly mean neoplastic lesions) should be distinguished from renal pseudotumours.
Whilst renal tumors can be broadly divided into primary and secondary (metastatic), benign and malignant or adult and pediatric tumors, they are more formal...
A Replogle tube is a medical device used in the treatment of babies with esophageal atresia. The tube is double-lumen and is inserted through the nostril and into the blind-ending esophageal pouch where it is then used to drain the pooled saliva. This prevents the secretions overflowing into the...
Respiratory distress syndrome (RDS) is a relatively common condition resulting from insufficient production of surfactant that occurs in preterm neonates.
On imaging, the condition generally presents as bilateral and relatively symmetric diffuse ground glass lungs with low volumes and a bell-s...
Retinoblastomas are the most common intraocular neoplasm found in childhood, and with modern treatment modalities are, in most cases, curable.
On imaging, they are generally characterized by a heterogeneous retinal mass with calcifications, necrotic components, and increased vascularization on ...
Retinopathy of prematurity (ROP) (formerly referred to as retrolental fibroplasia) is an ocular condition seen in the infant population. It often occurs bilaterally, although usually with significant asymmetry 1.
There is often a history of premature delivery, low birth weight, a...
Rhabdoid tumor of the kidney is a rare, highly aggressive malignancy of early childhood, closely related to atypical teratoid/rhabdoid tumors (AT/RT) of the brain (see rhabdoid tumors)
Rhabdoid tumors occur exclusively in children, with 60% occurring before the age of 1 year of ag...
Rhabdoid tumors are rare and extremely aggressive tumors of early childhood. They occur in a number of locations:
kidney: see malignant rhabdoid tumor of the kidney, most common
intracranial: see atypical teratoid/rhabdoid tumor (AT/RT)
soft tissues, including:
Rhabdomyosarcoma is a malignant tumor with skeletal muscle cell morphology. It is one of the tumors of muscular origin.
This article focuses on a general discussion of rhabdomyosarcomas. For location specific details, please refer to:
rhabdomyosarcomas of the biliary tract
Rhabdomyosarcomas of the genitourinary tract are uncommon tumors occurring in pelvic organs. It is a disease nearly exclusive to the pediatric population.
For a general discussion of this type of tumor, please refer to the article on rhabdomyosarcomas.
The peak incidence of tum...
Rhabdomyosarcomas of the orbit account for approximately 10-20% of all rhabdomyosarcomas and are usually found in children.
As with other locations, rhabdomyosarcomas in the orbit are overrepresented in males, and in Caucasians. They typically occur in children below the age of 1...
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.
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...
Rickets, less commonly known as rachitis, refers to osteomalacia in the pediatric population that occurs before fusion of the growth plate.
Rickets is seen in a number of distinct populations which include 4:
premature infants (especially if on parenteral nutrition)
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...
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 recognised 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 ...
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 (type II)
L: lower (type III)
T: through or transverse or together (type IV)
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.
Salter-Thompson classification for Legg-Calve-Perthes disease simplifies the Catterall classification into 2 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.
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...
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 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 venolobar ...
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, a scoliosis is any lateral spina...
Seckel syndrome is an autosomal recessive congenital dwarfing disorder.
The estimated incidence is ~1:10,000. There is no recognised gender predilection.
It is clinically characterized by many features including:
intrauterine growth restriction
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 septum pellucidum and, in two-thirds of patients hypothalamic-pituitary dysfunction. It is best thought of as being part of the holoprosencephaly spectrum (see cl...
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 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 encephalocoeles are congenital herniations of cerebral parenchyma through a cranial defect. There are three main types 1,2:
frontonasal encephalocoele (~50%): more common in Asia and Latin America 4
naso-ethmoidal encephalocoele (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 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 normal
situs ambiguus: an intermediate configuration with duplication (isomerism)
Situs is best thought...
Situs solitus 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 and the branching pattern of ...
The Sitz marker study is an older technique to estimate colonic transit time.
In constipation it can help distinguish between slow colonic transit and a defecation disorder.
The patient ingests a number of radio-opaque markers (plastic rings containing radio-opaque mat...
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.
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 the commonest hip abnormalities in adolescence and is bilateral in ~20% of cases.
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:
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...