Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

959 results found
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Hemihyperplasia

Hemihyperplasia, also known as hemihypertrophy, is asymmetry in size between the right and left of the body, more than can be attributed to normal variation. Terminology Hemihyperplasia is more scientifically correct than hemihypertrophy as the cells are hyperplastic rather than hypertrophied ...
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Hemimegalencephaly

Hemimegalencephaly is a rare congenital disorder of cortical formation with hamartomatous overgrowth all or a part of a cerebral hemisphere. This results from either increased proliferation or decreased apoptosis (or both) of developing neurons 2. Epidemiology Hemimegalencephaly is a cryptogen...
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Hepatic mesenchymal hamartoma

Hepatic mesenchymal hamartoma is an uncommon benign hepatic tumour. Some authors even consider this to be a developmental anomaly rather than a cystic neoplasm 9,12. Epidemiology It typically occurs in children and neonates, with most cases presenting within the first two years of life 3. Ther...
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Hepatoblastoma

Hepatoblastoma is the most common primary malignant liver tumour in children under four years of age who usually present with painless abdominal mass and raised AFP. It is tumour of embryonic origin. Epidemiology Most cases are seen during the first 18 months of life and diagnosis in adulthood...
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Hepatoblastoma histological classification

Although hepatoblastomas can be histologically classified into a variety of sub types, it is important to remember that with the possible exception of small cell undifferentiated sub type, prognosis is independent of histology when adjusted for stage gender and age 1. major categories epitheli...
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Hepatoblastoma (staging)

As expected there are a number of different staging systems for hepatoblastoma. Staging PRETEXT grouping system of paediatric liver tumours not specific to hepatoblastoma; used in all paediatric liver tumours Intergroup staging system specific for hepatoblastoma (see below) Intergroup stag...
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Hereditary connective tissue disease

Hereditary connective tissue diseases are a group of connective tissue disease that have a degree of inheritance risk. They include:  Marfan syndrome: genetic disease causing abnormal fibrillin Ehlers-Danlos syndrome: progressive deterioration of collagen and affects joints, heart valves, orga...
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Hereditary multiple exostoses

Hereditary multiple exostoses, also known as diaphyseal aclasis, is an autosomal dominant condition, characterised by the development of multiple osteochondromas. Epidemiology Hereditary multiple exostoses demonstrate an autosomal dominant inheritance pattern, with incomplete penetrance in fem...
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Herpes simplex encephalitis

Herpes simplex (HSV) encephalitis is the most common cause of fatal sporadic fulminant necrotising viral encephalitis and has characteristic imaging findings.  Two subtypes are recognised which differ in demographics, virus, and pattern of involvement. They are 1: neonatal herpes encephalitis ...
Article

Heterotaxy syndrome

Heterotaxy syndrome or situs ambiguus (also commonly, but etymologically less correctly, spelled situs ambiguous) is a disturbance in the usual left and right distribution of the thoracic and abdominal organs which does not entirely correspond to the complete or partial mirror image. It occurs ...
Article

Hiccups

Hiccups (or hiccoughs), medical term singultus (rarely used), are an unpleasant phenomenon, experienced by everyone on occasion, and usually self-limiting. However the much rarer intractable chronic form can be extremely debilitating. Epidemiology Hiccups are a symptom that has probably been e...
Article

Hilgenreiner line

The Hilgenreiner line is a line drawn horizontally through the inferior aspect of both triradiate cartilages. It should be horizontal, but is mainly used as a reference for Perkin line and measurement of the acetabular angle. Use of this line with the other lines and angles is used to diagnose ...
Article

Hindfoot valgus

Hindfoot valgus refers to malalignment of the hindfoot in which the mid-calcaneal axis is deviated away from the midline of the body. On the DP view, this results in an increase in the angle between the mid-calcaneal axis and the mid-talar axis (talocalcaneal angle) 1.  Despite abduction of th...
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Hindfoot varus

Hindfoot varus describes a relatively varus position of the calcaneus which is adducted and rotated under the talus. This is best appreciated on a weightbearing DP foot radiograph as a relative reduction in the angle formed between the mid-talar and mid-calcaneal axes (the talocalcaneal angle). ...
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Hindfoot equinus

Hindfoot equinus describes abnormal plantarflexion (calcaneotibial angle >90°)  of the foot that occurs in the hindfoot. It occurs in congenital talipes equinovarus and congenital vertical talus.
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Hip (Von Rosen view)

The Von Rosen view is a radiographic projection of the hip that demonstrates the relationship between the femoral head and the acetabulum. The von Rosen view is used in the diagnosis of developmental dysplasia of the hip in paediatric patients. This view forces dislocation of the affected hip(s...
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Hirschsprung disease

Hirschsprung disease is the most common cause of neonatal colonic obstruction (15-20%). It is commonly characterised by a short segment of colonic aganglionosis affecting term neonates, especially boys.  Epidemiology Hirschsprung disease affects approximately 1:5000-8000 live births. In short ...
Article

Hoffa's fat pad herniation

Hoffa's fat pad herniation is defined as herniation of infrapatellar fat through a defect in the lateral retinaculum. It is an uncommon cause of an anterolateral knee mass often detected at the fully flexed knee 1. Clinical presentation Mainly occurs in preschool-aged and young children as a p...
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Holoprosencephaly

Holoprosencephaly (HPE) is a rare congenital brain malformation resulting from incomplete separation of the two hemispheres. Classically three subtypes have been recognised, however additional entities are now included in the spectrum of the disease. The three main subtypes, in order of decreas...
Article

Homocystinuria

Homocystinuria is a rare congenital disorder of metabolism.  Clinical presentation The disease may affect one or more of the systems below 1,2: eye: ectopia lentis CNS: seizures, dystonia, developmental delay skeletal: scoliosis, pectus excavatum, long limbs vascular: thromboembolism Path...
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Humeral condyle fracture

Humeral condyle fractures represent fractures through the medial or lateral distal humeral condyles. 
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Hunka classification of neonatal septic arthritis of the hip

Type I: Absent or minimal femoral head changes. Type II: A: deformity of the femoral head with intact physis. B: deformity of the femoral head with premature physeal closure. Type III: Pseudarthrosis of the femoral neck. Type IV: A:Complete destruction of the capital femoral epiphysis wit...
Article

Hurler syndrome

Hurler syndrome is one of the mucopolysaccharidoses (MPS type I). It carries an autosomal recessive inheritance and manifests in the first years of life. It is clinically characterised by mental retardation, corneal clouding, deafness and cardiac disease, with death resulting in the first decad...
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Hutchinson syndrome

Hutchinson syndrome is limping and irritability due to skeletal metastases from neuroblastoma. It should not be confused with: Hutchinson triad Hutchinson pupil Hutchinson freckle Hutchinson teeth Hutchinson sign History and etymology Described by Sir Robert Grieve Hutchison (1871-1960),...
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Hybrid lesion (paediatric chest)

A hybrid lesion in paediatric chest radiology refers to a combination of a congenital pulmonary airways malformation (CPAM) and a pulmonary sequestration (most commonly extralobar). It falls under a type of bronchopulmonary foregut malformation. Due to more sophisticated imaging, they are increa...
Article

Hydranencephaly

Hydranencephaly is a rare encephalopathy that occurs in-utero. It is characterised by destruction of the cerebral hemispheres which are transformed into a membranous sac containing cerebrospinal fluid and the remnants of cortex and white matter 1. Porencephaly is considered a less severe degree...
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Hydrocele of the canal of Nuck

Hydrocele of the canal of Nuck is a rare condition in female children caused by a failure of complete obliteration of the canal of Nuck 1. The canal of Nuck is an abnormal patent pouch of peritoneum extending anterior to the round ligament of the uterus into the labia majora 2. Incomplete oblite...
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Hydronephrosis (grading)

Grading systems of hydronephrosis have been devised to communicate the degree of upper collecting system dilatation. The most common system used (Society of Fetal Ultrasound, SFU) was originally designed for grading neonatal and infant hydronephrosis: grade 0 no dilatation, calyceal walls are ...
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Hypertrophic pyloric stenosis (ultrasound measurements mnemonic)

Hypertrophic pyloric stenosis can be characterised in ultrasound studies by the measurements of the hypertrophic muscle. Although the criteria can vary from publication to publication, an easy way to keep in mind those values is remembering the first digits of the number "pi", also represented b...
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Hyperuricaemia

Hyperuricaemia is defined as elevated levels of uric acid (≥7 mg/dL) in the blood and may be caused by either urate overproduction or underexcretion. Clinical presentation Patients with hyperuricaemia may be asymptomatic or have symptoms and signs relating to one of the complications of hyperu...
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Hypervitaminosis A

Hypervitaminosis A results from an excess of vitamin A. It usually manifests in children, and one recognised cause is administration from 13-cis retinoic acid for treatment of cancers such as neuroblastoma. Clinical presentation Manifestations can differ depending on whether it is an acute or ...
Article

Hypophosphatasia

Hypophosphatasia refers to a rare metabolic disorder characterised by deficient serum alkaline phosphatase activity. The effects of hypophosphatasia are primarily seen in the skeletal system. The condition has marked variation in clinical expression (see subtypes). Epidemiology The true incide...
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Hypoplastic left heart syndrome

Hypoplastic left heart syndrome (HLHS) is a cyanotic congenital cardiac anomaly where affected individuals can have profound cyanosis and cardiac failure. It is one of the commonest causes for a neonate to present with congestive cardiac failure and the 4th most frequent cardiac anomaly to mani...
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Hypoplastic right heart syndrome

Hypoplastic right heart syndrome is a congenital cardiac anomaly. It is characterised by an underdeveloped right side of the heart, including the right ventricle, tricuspid valve, pulmonary valve, and pulmonary arteries. Epidemiology It may be present in around 1.1% of stillbirths and is rarer...
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Hypospadias

Hypospadias refers to a type of congenital malformation affecting the male external genitalia. Epidemiology The estimated prevalence is ~2 (range 0.2-4.1) per 1000 live births. Pathology The urethral meatus is abnormally positioned proximally and ventrally to its normal position. It is thou...
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Hypovitaminosis A

Hypovitaminosis A results from inadequate intake of vitamin A, fat malabsorption, or liver disorders and produces a variety of epithelial alterations. Epidemiology The World Health Organization currently estimates that 45-122 countries have a vitamin A deficiency of public health significance ...
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Hypovitaminosis C (scurvy)

Scurvy (also known as Barlow disease in infants or historically, as scorbutus) is a condition characterised by an increased bleeding tendency and impaired collagen synthesis resulting in osteoporosis and impaired wound healing. It is caused by a dietary lack of vitamin C (ascorbic acid). Epidem...
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Hypovitaminosis E

Hypovitaminosis E is well-recognised but rare. It is usually due to the malabsorption of vitamin E, e.g. cystic fibrosis or pancreatic failure. It manifests as dysfunction of the CNS, characteristically presenting with a tremor and ataxia. Tendon reflexes are often absent. Clinically and radiol...
Article

IgA vasculitis

IgA vasculitis (formerly known as Henoch-Schonlein purpura (HSP)) is a type of non-thrombocytopenic immune-mediated small vessel acute leukocytoclastic vasculitis. It tends to occur in the paediatric population (peak incidence 3-10 years) 3. In order to differentiate from other types of vascul...
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Ileal atresia

Ileal atresia is a congenital abnormality where there is significant stenosis or complete absence of a portion of the ileum. There is an increased incidence in those with chromosomal abnormalities. This article will focus on ileal atresia alone but bear in mind that some cases correspond to jej...
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Imperforate hymen

Imperforate hymen is a congenital condition in which the hymen lacks a normal opening. Epidemiology It happens in 0.1% of the female population, usually an isolated finding.  Clinical features Primary amenorrhea with cyclic lower abdominal pain during menarche age. An imperforate hymen can b...
Article

Incomplete fracture

Incomplete fractures are a heterogeneous group of fractures that predominantly occur in the long bones of paediatric patients. Rang 1 describes a continuum of fractures that occur with increasing longitudinal force applied along the length of the bone. At the point where force exceeds the struct...
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Incomplete hippocampal inversion

Incomplete hippocampal inversion describes the situation where the normal inversion of the hippocampus fails to happen during development. Terminology Incomplete hippocampal inversion is the most correct description of this finding. Hippocampal malrotation is a term used by some authors 1 alth...
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Increased bone age

A generalised acceleration in bone maturation can result from a number of aetiological factors. They include: endocrine disorders idiopathic isosexual precocious puberty hypothalamic or parathalamic lesion with sexual precocity: e.g. craniopharyngioma astrocytoma hypothalamic hamartoma hy...
Article

Infantile cervical ligament oedema

Infantile cervical ligament oedema can typically be seen when infants have suffered accidental or abusive head and neck trauma. The finding is best seen on sagittal STIR images. Terminology The posterior ligamentous complex refers to the ligamentum flavum and interspinous ligaments. The anteri...
Article

Infantile fibrosarcoma of the lung

Infantile fibrosarcoma of the lung, also known as primary bronchopulmonary fibrosarcoma, is a very rare spindle-cell tumour. Epidemiology More than 80% of cases are reported to occur within the 1st year of life. There is a slight predominance in male infants 1,2. Clinical presentation Patien...
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Infantile haemangioma

Infantile haemangiomas are benign vascular neoplasms that are the most common head and neck tumours of infancy. They can occur virtually anywhere, but the majority are found in the head and neck regions. This article aims to be a generic discussion of the condition, for detailed and more specif...
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Infantile hepatic haemangioma

Infantile hepatic haemangiomas (IHH) are a liver lesion composed of large endothelial-lined vascular channels seen in fetuses and neonates. It should not be confused with a hepatic epithelioid haemangioendothelioma, which occurs in older patients. Terminology Those benign tumours were previous...
Article

Infectious mononucleosis

Infectious mononucleosis (also known as glandular fever) is the term for infection with Epstein-Barr Virus (EBV). The infection classically occurs in teenagers and young adults. It usually is diagnosed clinically supported by serum testing, but also may have suggestive imaging findings. Epidemi...
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Ingested foreign bodies in children

Ingested foreign bodies in children are common as the world is a curious place to young children, who will put anything and everything into their mouth, and will often inadvertently swallow.  The usual practice is for plain films of the chest/abdomen to identify a foreign body. Epidemiology P...
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Innominate artery compression syndrome

Innominate artery compression syndrome, also known as brachiocephalic artery compression syndrome, is a rare cause of tracheal stenosis that occurs in the paediatric population. Pathology It can only occur in the presence of an aberrantly positioned thymus that forces the aortic arch or innomi...
Article

Interatrial septal aneurysm

Interatrial septal aneurysm or atrial septal aneurysm (ASA) is defined as an abnormal protrusion of the interatrial septum. The exact length of the protrusion that defines an interatrial septal aneurysm varies in the literature, ranging from >11 mm to >15 mm beyond normal excursion in adults 4,5...
Article

Interrupted aortic arch

Interrupted aortic arch (IAA) is an uncommon congenital cardiovascular anomaly where there is a separation between the ascending and descending aorta. It can either be complete or connected by a remnant fibrous band. An accompanying large ventricular septal defect (VSD) and/or patent ductus arte...
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Intestinal failure

Intestinal failure is when a patient's native bowel is unable to digest and absorb  the food, electrolytes and fluids needed for normal growth and development.  Clinical presentation This often includes intractable diarrhoea, weight loss, dehydration, electrolyte imbalance, and malnutrition. ...
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Intestinal malrotation

Intestinal malrotation is a congenital anatomical anomaly that results from an abnormal rotation of the gut as it returns to the abdominal cavity during embryogenesis. Although some individuals live their entire life with malrotated bowel without symptoms, the abnormality does predispose to mid...
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Intestinal nonrotation

Intestinal nonrotation is a congenital anomaly of the intestines that results in the small bowel occupying the right side of the peritoneal cavity and the colon predominantly on the left. It is sometimes thought of as a subtype of intestinal malrotation. Epidemiology Nonrotation is estimated ...
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Intestinal transplant

Intestinal transplantation is a surgical treatment for intestinal failure. It is one of the most rarely performed transplant procedures performed, exclusively involving the transplantation of donor small bowel to a recipient, with an ileostomy formation.  Due to the high risk of complications w...
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Intra-abdominal calcification (neonatal)

Intra-abdominal calcification in a neonate can be caused by a number of pathologies that cause calcification within the peritoneal space or within organs. Pathology Aetiology Meconium peritonitis The commonest cause is meconium peritonitis which is the result of aseptic peritonitis secondary...
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Intracranial cystic lesions in the perinatal period

Intracranial cystic lesions in the perinatal period can carry a relatively wide differential which includes: Supratentorial cystic lesions cysts arachnoid cyst choroid plexus cyst connatal cyst holoprosencephaly multicystic encephalomalacia periventricular leukomalacia porencephalic cys...
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Intracranial teratoma

Intracranial teratomas are uncommon intracranial neoplasms, which can have a bewildering variety of components and thus a wide range of appearances. They can be divided into two broad categories, intra- and extra-axial, which differ in epidemiology and clinical presentation. Another method of cl...
Article

Intramembranous ossification

Intramembranous ossification describes the process of ossification from mesenchymal cells (stem cells) without a cartilaginous template and is involved in the healing process of fractures. The stages of intramembranous ossification osteogenesis are as follows: mesenchymal cells differentiate in...
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Intraventricular haemorrhage of the newborn

Intraventricular haemorrhage of the newborn is a distinct entity and considered separately from intraventricular haemorrhage (IVH) in adults. In neonates, IVH is the result of germinal matrix haemorrhage, which ruptures through the ependymal lining and into the lateral ventricles. Other causes...
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Intussusception

Intussusception occurs when one segment of bowel is pulled into itself or a neighbouring loop of bowel by peristalsis. It is an important cause of an acute abdomen in children and merits timely ultrasound examination and reduction to preclude significant sequelae including bowel necrosis. When o...
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Intussusception reduction

Intussusception reduction is a procedure performed in paediatric patients who have an ileocolic intussusception. There are several ways that reduction can be achieved radiologically: air-reduction under fluoroscopic guidance water-reduction under fluoroscopic guidance physical reduction unde...
Article

Ischiopubic synchondrosis asymmetry

Ischiopubic synchondrosis asymmetry (also known as van Neck-Odelberg disease) is characteristic enlargement of one of the ischiopubic synchondroses. It is largely considered an anatomic variant of skeletal developmental, given that it is a common and usually asymptomatic finding. However, some ...
Article

Isolated inferior vermian hypoplasia

Isolated inferior vermian hypoplasia (IIVH), also referred as part of Dandy-Walker variant (DWV), is a congenital malformation characterised by partial absence of the inferior portion of the cerebellar vermis. Terminology The term Dandy-Walker variant was created to include those malformations...
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Isomerism

Isomerism is a term which in general means 'mirror-image'. It is used in the context of heterotaxy and is of two types: left isomerism right isomerism Left isomerism Mirror image of the structures on the left side of the chest along the left-right axis of the body, i.e. patients with isomeri...
Article

Jacobsen syndrome

Jacobsen syndrome (also known as the chromosome 11q deletion syndrome) is a rare chromosomal anomaly that results from deletion of the terminal region of chromosome 11. It results in intellectual disabilities, a distinctive facial appearance and a variety of physical problems including heart def...
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Jarcho-Levin syndrome

The Jarcho-Levin syndrome (JLS) or spondylothoracic dysostosis is a rare autosomal recessive heterogeneous disorder that can occur with variable severity. Previously the condition spondylocostal dysostosis was also considered as part of the JLS spectrum but is now considered a distinct pathologi...
Article

Jejunal atresia

Jejunal atresia is a congenital anomaly characterised by obliteration of the lumen of the jejunum. The site of the atresia can be anywhere from the ligament of Treitz to the jejunoileal junction. There can be more than one atretic segment. This article will focus on jejunal atresia alone but be...
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Johanson-Blizzard syndrome

Johanson-Blizzard syndrome is a disorder of ectodermal dysplasia with a wide variability in its manifestations. It is thought to have autosomal recessive inheritance. Clinical presentation There is a wide variability in the clinical presentation, but common features are: low birth weight hyp...
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Joubert syndrome

Joubert anomaly, also known as vermian aplasia or molar tooth midbrain-hindbrain malformation, is an autosomal recessive disorder where there is a variable degree of cerebellar vermal agenesis.  Terminology When associated with anomalies of the kidneys, liver and/or eyes then the term Joubert ...
Article

J-shaped sella

A J-shaped sella is a variant morphology of the sella turcica, whereby the tuberculum sellae is flattened, thus forming the straight edge of the "J". The dorsum sellae remains rounded and forms the loop of the "J". Differential diagnosis Differential diagnosis for a J-shaped sella includes 1,2...
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Juberg-Hayward syndrome

Juberg-Hayward syndrome (JHS), also known as the oro-cranio-digital syndrome, is a rare autosomal recessive syndrome characterised by the association of the following:  growth retardation microcephaly cleft lip and palate minor vertebral and rib anomalies 4 horseshoe kidneys 4 thumb anomal...
Article

Juvenile granulosa cell tumour (ovary)

Juvenile granulosa cell tumours of the ovary (JGCT) are a less common subtype of granulosa cell tumour of the ovary (~5% of cases). They are classified as ovarian sex cord / stromal tumours. Epidemiology It typically occurs in premenarchal girls and young women. The mean age of presentation is...
Article

Juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA), also known as juvenile rheumatoid arthritis, is the most common chronic arthritic disease of childhood and corresponds to a group of different subtypes. Epidemiology The estimated incidence is ~13 per 100,000 per annum 3. By definition, symptoms must start ...
Article

Juvenile nasopharyngeal angiofibromas (staging)

Staging of juvenile nasopharyngeal angiofibromas is performed with cross-sectional imaging and relies on the identification of local tumour extent, and invasion of adjacent spaces. For a discussion of this entity please refer to the parent article: juvenile nasopharyngeal angiofibroma.  The sta...
Article

Juvenile osteoporosis

Juvenile osteoporosis refers to osteoporosis occurring in children. Pathology Aetiology It can arise from a number of causes 1-4: primary conditions osteogenesis imperfecta Bruck syndrome osteoporosis pseudoglioma syndrome Ehlers-Danlos syndrome Marfan syndrome homocystinuria secondar...
Article

Juvenile polyposis syndrome

Juvenile polyposis syndrome, also referred as familial juvenile polyposis, is one of the polyposis syndromes and consists of hundreds of juvenile polyps. Epidemiology Presentation in the second decade is most common 2. Clinical presentation Rectal bleeding, bowel obstruction and intussuscept...
Article

Kabuki syndrome

Kabuki syndrome (Niikawa-Kuroki syndrome) is a rare polydysplasia that is thought to be more common in Japan. Epidemiology Estimated incidence of 1:32,000 in Japan. Sporadically seen elsewhere in the world. The reason for the disparity in incidence is controversial. Pathology The cause for t...
Article

Kartagener syndrome

Kartagener syndrome is a subset of primary ciliary dyskinesia, an autosomal recessive condition characterised by an abnormal ciliary structure or function, leading to impaired mucociliary clearance.  Epidemiology The prevalence of primary ciliary dyskinesia is approximately 1 in 12,000-60,000 ...
Article

Kasabach-Merritt syndrome

Kasabach-Merritt syndrome, also known as haemangioma thrombocytopenia syndrome, is a rare life-threatening disease found in infants in which a rapidly growing vascular tumour is responsible for thrombocytopenia, microangiopathic haemolytic anaemia and consumptive coagulopathy. Pathology Vascul...
Article

Kasai classification

Kasai classification is used to describe the three main anatomical types of biliary atresia. Classification type I: obliteration of common bile duct (patent cystic and common hepatic duct) type II IIa: obliteration of common hepatic duct (patent cystic and common bile duct), sometimes with a...
Article

Kashin-Beck disease

Kashin-Beck disease (KBD) is a rare chronic condition, comprising an osteochondropathy with a concurrent necrosis of the joints. The presentation is similar to rheumatoid arthritis. Pathologically, the lack of dietary selenium is important. The lack of selenium affects the functioning of antioxi...
Article

Kawasaki disease

Kawasaki disease is a small to medium vessel vasculitis predominantly affecting young children. It can affect any body organ but there is a predilection for the coronary vessels. Epidemiology Japan has the highest incidence in the world, with an annual incidence of 300/100,000 children under t...
Article

Kearns-Sayre syndrome

Kearns-Sayre syndrome (KSS), also known as oculocraniosomatic disorder, is a rare multisystem mitochondrial disorder.  Clinical presentation The patient often presents with progressive external ophthalmoplegia 1. Neurologic symptoms develop in childhood or adolescence, usually before 20 years ...
Article

Kernicterus

Kernicterus, also known as chronic bilirubin encephalopathy, describes the chronic, toxic, permanent sequelae of high levels of unconjugated bilirubin on the central nervous system of infants. It is part of the spectrum of bilirubin-induced neurologic dysfunction, which also includes acute bilir...
Article

Keyhole sign (posterior urethral valves)

The keyhole sign is an ultrasonographic sign seen in boys with posterior urethral valves. It refers to the appearance of the proximal urethra (which is dilated) and an associated thick-walled distended bladder which on ultrasound may resemble a keyhole.
Article

Kirner deformity

Kirner deformity is characterised by a curvature of the distal phalynx of the 5th digit in both a palmar and radial direction. Epidemiology The deformity typically presents in late childhood to early adolescence, although a mild deformity may be present at birth. Both sexes are affected, altho...
Article

Klinefelter syndrome

Klinefelter syndrome (KS) is a chromosomal anomaly, which in most cases is characterised by 47 chromosomes instead of the usual 46. Epidemiology The estimated incidence is 0.15-0.2% of live births. Clinical presentation the testes are normal prior to puberty and small in post pubertal testes...
Article

Klippel-Feil syndrome

Klippel-Feil syndrome is a complex heterogeneous entity that results in cervical vertebral fusion. Two or more non-segmented cervical vertebrae are usually sufficient for diagnosis. Epidemiology There is a recognised female predilection 1. Klippel-Feil syndrome has an incidence of 1:40,000-42,...
Article

Kniest dysplasia

Kniest dysplasia is rare type of short limbed skeletal dysplasia. Pathology Genetics It is thought to carry an autosomal dominant inheritance. Kniest dysplasia is one of a spectrum of skeletal disorders caused by mutations in the COL2A1 gene, which encodes for type II collagen (therefore clas...
Article

Köhler disease

Köhler disease is an eponymous term referring to childhood-onset osteonecrosis of the navicular bone in the foot. Mueller Weiss syndrome is the adult counterpart of navicular bone osteonecrosis 4,5 . Epidemiology It typically presents in the paediatric population (4-6 years of age) and there i...

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