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.
The prevalence of primary ciliary dyskinesia is approximately 1 in 12,000-60,000 ...
Kasabach-Merritt syndrome, also known as haemangioma thrombocytopaenia syndrome, is a rare life-threatening disease found in infants in which a rapidly growing vascular tumour is responsible for thrombocytopaenia, microangiopathic haemolytic anaemia and consumptive coagulopathy.
Kasai classification is used to describe the three main anatomical types of biliary atresia.
type I: obliteration of common bile duct (patent cystic and common hepatic duct)
IIa: obliteration of common hepatic duct (patent cystic and common bile duct), sometimes with a...
Kawasaki disease (KD) 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.
An autoimmune aetiology has been postulated. It is generally self limiting but acute fatalities are ...
Kearns-Sayre syndrome (KSS), also known as oculocraniosomatic disorder, is a rare multisystem mitochondrial disorder.
The patient often presents with progressive external ophthalmoplegia 1. Neurologic symptoms develop in childhood or adolescence, usually before 20 years ...
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 associated thick walled distended bladder which on ultrasound may resemble a key hole.
Kirner deformity is characterised by a curvature of the distal phalynx of the 5th digit in both a palmar and radial direction.
The deformity typically presents in late childhood to early adolescence, although a mild deformity may be present at birth. Both sexes are affected, altho...
Klinefelter syndrome (KS) is a chromosomal anomaly, which in most cases is characterised by 47 chromosomes instead of the usual 46.
The estimated incidence is 0.15-0.2% of live births.
the testes are normal prior to puberty and small in post pubertal testes...
Klippel-Feil syndrome (KFS) is a complex heterogeneous entity that results in cervical vertebral fusion. Two or more non-segmented cervical vertebrae are usually sufficient for diagnosis.
There is a recognised female predilection 1. KFS has an incidence of 1:40,000-42,000 2.
Kniest dysplasia is rare type of short limbed skeletal dysplasia.
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. This gene provides instructions for making a prote...
Köhler disease is an eponymous term referring to chilhood onset avascular necrosis of the navicular bone in the foot. Mueller Weiss syndrome is the adult counterpart of navicular bone avascular necrosis. 4,5
It typically presents in the paediatric population (4-6 years age) and th...
Krabbe disease, also known as globoid cell leukodystrophy, is an autosomal recessive leukodystrophy.
Can vary and depends on age of onset 5.
loss of developed milestones
Kump's bump is a superior convexity of the growth plate located in the anteromedial quadrant of the distal tibia physis, which is the first site of physeal fusion. Closure usually occurs at about 12-13 years of age. The Kump's bump should not to be mistaken for a fracture or abnormal physeal fus...
L-2-hydroxyglutaric aciduria is a rare organic aciduria but has characteristic MRI findings especially in the early stages 1. This can allow for early diagnosis, often prior to biochemical investigations.
As it is inherited in an autosomal recessive fashion, consanguineous marriag...
Labrune syndrome (LS) is a rare condition that consists of a triad of leukoencephalopathy, cerebral calcifications and cysts.
LS is an extremely rare condition, with no more than 10 cases reported in literature 2. The onset occurs from early infancy to adolescence; few cases have...
Langerhans cell histiocytosis (LCH) is a rare multi-system disease with a wide and heterogeneous clinical spectrum and variable extent of involvement.
The disease is more common in the paediatric population, with a peak incidence between one and three years of age 5. Incidence is...
The central nervous system (CNS) is an uncommonly involved organ system in Langerhans cell histiocytosis (LCH). Involvement of the CNS is related but distinct from involvement of the skull base or craniofacial structures, which are discussed separately in the article skeletal manifestations of L...
The skeleton is the most commonly involved organ system in Langerhans cell histiocytosis (LCH) and is by far the most common location for single-lesion LCH, often referred to as eosinophilic granuloma (EG) (the terms are used interchangeably in this article). For a general discussion of this dis...
The Lasjaunias classification, at the time of writing (mid 2016), is one of the two commonly used systems for classifying vein of Galen malformations. It relies on dividing the entity into choroidal or mural types, depending on the number and origin of feeding arteries.
Lateral epicondyle fractures are rare epicondylar fractures. They are much rarer than medial epicondyle fractures and represent avulsion of the lateral epicondyle. They are usually seen in the setting of other injuries 1-3.
Incidence typically peaks in the paediatric age group (6...
Lateral humeral condyle fractures are relatively common elbow fractures that predominantly occur in children.
They represent ~12.5% (range 5-20%) of elbow fractures in children and are the second most common paediatric elbow fracture after supracondylar fractures.
They occur in ...
Leaky lung syndrome (LLS) refers to a form of non-cardiogenic pulmonary oedema.
Pulmonary oedema due to increased capillary permeability.
LLS is considered as mild form of a part of spectrum of acute lung injury with ARDS at the other end of spectrum ...
Leg bowing in children is common and often developmental.
The differential includes:
Blount disease: tibia vara
neurofibromatosis type 1
usually lateral bowing
Staging of Legg-Calve-Perthes syndrome refers to x-ray abnormalities, and represents 4 phases of the disease:
stage I: early
asymmetric femoral epiphyseal size (smaller on the affected side)
apparent increased density of the femoral head epiphysis
widening of the medial joint space
Leigh syndrome, also known as subacute necrotising encephalomyelopathy (SNEM), is a mitochondrial disorder with progressive neurodegeneration that invariably leads to death, usually in childhood.
Leigh syndrome is encountered in approximately 1 in 40,000 births, although some popu...
Leptomeningeal cysts, also known as growing skull fractures, are an enlarging skull fracture that occurs near post-traumatic encephalomalacia. The term cyst is actually a misnomer, as it is not a cyst, but an extension of the encephalomalacia. Hence, it is usually seen a few months post-trauma.
Lethal omphalocele-cleft palate syndrome is, as the name suggests, characterised by the association of omphalocele and cleft palate.
Prevalence is assumed to be <1 per 1,000,000. It has been postulated that this syndrome is likely to be an autosomal recessive condition 1.
History and etymolog...
The leukodystrophies are dysmyelinating disorders which typically, although not invariably, affect children. They include:
lysosomal storage diseases
globoid cell leukodystrophy (Krabbe disease)
Liddle's syndrome is an autosomal dominant condition which inhibits the normal degradation of the ENaC sodium channel, resulting in findings that mimic Conn's syndrome (hyperaldosteronism); hypernatraemia, hypokalaemia and elevated serum bicarbonate. Typically patients are asymptomatic other tha...
The line of Klein describes a line along the superior edge of the neck of the femur. It is useful in detecting early slipped upper femoral epiphysis (SUFE) in adolescents. The line should normally intersect the lateral part of the superior femoral epiphysis. If the line of Klein fails to inters...
Lipoblastoma is a rare, benign, encapsulated tumour arising from embryonic white fat.
It occurs primarily in infancy and early childhood (more than 90% before age 3). It most often occurs in the extremities and trunk, although it can be seen in other areas 1. The entity was originally describe...
Lipoblastomatosis is an uncommon presentation of a benign fatty neoplasm. The condition is more common in infants and young children. It differs from a lipoblastoma in that it is extensive and infiltrative.
Lipoblastomatosis consists of immature adipose tissue surrounding myxomatous...
Lipomyelocele is one of the most common closed spinal dysraphism. It is seen in thoracolumbar region and usually presents as a fatty subcutaneous mass.
It is twice as common as lipomyelomeningocele.
Affected individuals are usually asymptomatic at birth, but many (~ 50%)...
The lissencephaly-pachygyria spectrum is useful in describing the spectrum of diseases that cause relative smoothness of the brain surface and includes:
agyria: no gyri
pachygyria: broad gyri
lissencephaly: smooth brain surface
It is a basket term for a number of congenital cortical malforma...
Lithopaedions, also referred as stone babies, are a rare phenomenon which occurs most commonly when a fetus dies during an ectopic pregnancy.
The estimated incidence is at ~ 1.5 to 1.8% of abdominal ectopic pregnancies 4.
If the dead fetus is too large to be re-absorbe...
Paediatric liver lesions are a heterogeneous group that include infiltrative lesions and those that demonstrate mass effect. Moreover, they may be solitary or multiple, benign or malignant:
benign liver tumours
malignant liver tumours
There are differing frequencies of both beni...
Lobar holoprosencephaly is the least severe of the classical subtypes of holoprosencephaly (HPE), characterised by the presence of the inter-hemispheric fissure along almost the entire midline, and with the thalami being completely or nearly completely separated 5.
As with all types of HPE, it ...
Loeys-Dietz syndrome (LDS) is an autosomal dominant genetic syndrome which has many features similar to Marfan syndrome.
The syndrome features a classical triad of 1:
arterial tortuosity and aneurysms
bifid uvula or cleft palate
It is caused by mutations in the gene...
Luckenschadel skull, also known as lacunar skull or craniolacunae, is a dysplasia of the membranous skull vault and is associated with Chiari II malformations (seen in up to 80% of such cases). The inner table is more affected than the outer, with regions of apparent thinning (corresponding to n...
Lumbar Scheuermann disease is a type of variant Scheuermann disease where there are some radiological features of Scheuermann's disease without an abnormal kyphosis.
On radiographs, affected individuals can have vertebral end plate changes, disc space narrowing, and anterior Schmorl's nodes, bu...
Lymphangiomas are benign lesions of vascular origin that show lymphatic differentiation. It is considered the lymphatic equivalent of a haemangioma of blood vessels.
This article focuses the general features of lymphangiomas. For a specific discussion in other locations, please refer to the ar...
Lytic skull lesions have a relatively wide differential that can be narrowed, by considering if there are more than one lesion and whether the mandible is involved.
lytic skeletal metastases
epidermoid - scalloped border with a sclerotic rim
M-line of Cremin is an imaginary line that can be used to determine the level at which the blind pouch ends in anal atresia, determining whether the anal atresia is a high or a low type.
The line is drawn perpendicular to the long axis of the ischium on the lateral view and passes through the j...
Macrodystrophia lipomatosa is a rare form of localised gigantism, and many terms have been used interchangeably, with resulting confusion. They include macrodactyly, megalodactyly, digital gigantism, macromelia, partial acromegaly, macrosomy, and limited gigantism 3.
It is worth noting that ma...
Macroglossia means an enlarged tongue. It may be absolute (greater than the 95th centile) or relative (enlarged compared with oral cavity).
Recognised associations include:
tends to be a relative macroglossia
may also have intermi...
Madelung deformity is due to premature closure or defective development of the ulnar third of the distal epiphysis of the radius. This deformity results in a radial shaft that is bowed with increased interosseous space and dorsal subluxation of the distal radioulnar joint.
It can be bilateral ...
Major aortopulmonary collateral arteries (MAPCAs) are persistent tortuous fetal arteries that arise from the descending aorta and supply blood to pulmonary arteries in the lungs usually at the posterior aspect of hilum.
Embryologically, the intersegmental arteries regress with the no...
Paediatric malignant liver tumours are rare, some of which occur only in children but that are similar to those that occur in adults.
Malignant liver tumours account for ~1% of paediatric malignancies 2.
Broadly, any malignant liver mass can be defined as a metastasis ...
Maple syrup urine disease (MSUD) is a very rare metabolic disorder. It is an inborn error of amino acid metabolism, which classically affects the brain tissue resulting in impairment or death if untreated.
Manifests itself in the first few days of life (12-24 hours) with ...
Marshall-Smith syndrome (MSS) is a rare genetic syndrome primarily comprising of the triad of facial dysmorphism, failure to thrive and accelerated osseous maturation 5. Many cases however have wider clinical spectrum.
overgrowth - fetal macrosomia
failure to thriv...
McKusick Kaufman syndrome (MKS) is an autosomal recessive multiple malformation syndrome primarily characterised by
hydrometrocolpos - vaginal atresia
congenital heart disease
Meckel diverticulum is a congenital intestinal diverticulum due to fibrous degeneration of the umbilical end of the omphalomesenteric (vitelline) duct that occurs around the distal ileum. It is considered the most common structural congenital anomaly of the gastrointestinal tract.
Meckel-Gruber syndrome (MGS) is classically characterised by the triad of:
renal cystic dysplasia: multiple renal cysts (present most cases)
occipital encephalocoele / holoprosencephaly (~70%)
postaxial polydactyly: usually hexadactyly (~65%)
Additional hepatic developmental defects and hepa...
Meconium aspiration occurs secondary to intrapartum or intrauterine aspiration of meconium, usually in the setting of fetal distress, and usually in term or post-term infants.
Aspirated meconium can cause small airways obstruction and a chemical pneumonitis.
Meconium ileus refers to a neonatal bowel obstruction of the distal ileum due to abnormally thick and impacted meconium. Unlike in the meconium plug syndrome, the meconium is abnormal in consistency.
Meconium ileus is more common in white populations and affects both sexes almost ...
Meconium peritonitis refers to a sterile chemical peritonitis due to intra-uterine bowel perforation and spillage of fetal meconium into the fetal peritoneal cavity. It is a common cause of peritoneal calcification.
The estimated prevalence is at ~1 in 35,000.
Meconium plug syndrome refers to a functional colonic obstruction in a newborn due to an obstructing meconium plug. It is usually transient and affects the left colon with meconium plugging the bowel distal to this segment. In this situation, it is also termed the small left colon syndrome.
Meconium pseudocyst formation is a complication that can occur with meconium peritonitis.
It occurs when the extruded meconium becomes walled off within the peritoneal space.
May be seen as a rim calcified mass within the abdomen.
Medial epicondyle fractures represent almost all epicondyle fractures and occur when there is avulsion of the medial epicondyle. They are typically seen in children, and can be challenging to identify. Failure to diagnose these injuries can lead to significant long term disability.
Medial pneumothorax refers to the abnormal collection of air on medial aspect of the pleural cavity. This occurs when the quantity of air is small.
Chest radiograph (supine)
Seen as a linear lucent area along the medial aspect of lung at the interface of the pleural surf...
Medial stripe sign refers to an area of increased lucency at the interface of the medial lung and the mediastinum in case of medial pneumothorax. A small volume of pneumothorax generally accumulates anteriorly or medially which can be difficult to detect hence this sign holds a certain significa...
Medullary cystic disease complex belongs to group of paediatric cystic renal diseases charaterised by progressive tubular atrophy with glomerulosclerosis (chronic tubulointerstitial nephritis) and multiple small medullary cysts.
There is no recognised gender predilection
Medulloblastomas are the most common malignant brain tumour of childhood. They most commonly present as midline masses in the roof of the 4th ventricle with associated mass effect and hydrocephalus. Treatment typically consists of surgical resection, radiation therapy, and chemotherapy, with the...
Melanotic neuroectodermal tumour of infancy (MNTI) is a rare pigmented tumour that primarily affects the calvarium or facial skeleton of children, typically during infancy. It is usually a benign tumour, albeit locally aggressive.
Most cases are diagnosed during infancy, usually w...
Meningoceles are protrusions of the meninges through a defect or weak point in the skull or spine, usually involving the soft tissues beneath the surface of the skin. They are typically categorized into congenital, iatrogenic (e.g. following a craniotomy, sinus surgery, or as a laminectomy compl...
Menkes disease, also known as trichopoliodystrophy or Kinky hair kinky vessel syndrome, is an X-linked recessive disorder that results in a derangement in copper handling. It results in low copper levels and subsequently, deficiency in copper dependant mitochondrial enzymes.
MERRF (myoclonic epilepsy with red ragged fibres) is a rare, multisystem mitochondrial disorder.
Patients usually present in late adolescence or early adulthood with 1,2,3
vision and/or hearing loss
A mesenchymal hamartoma of the chest wall is a very rare benign chest wall tumour. It is sometimes classified as a non-neoplastic developmental anomaly rather than a tumour.
They typically present in neonates or infants 1-3.
Many present with a chest wall m...
Mesomelia refers to a shortening of the middle (intermediate) portion of a limb.
mesomelia-synostoses syndrome (MSS) or mesomelic dysplasia with acral synostoses1
Ellis van-Creveld syndrome 2
Metachondromatosis refers to the rare combination of:
multiple enchondromatosis (Ollier disease) and
osteochondromatosis (diaphyseal aclasis)
In contrast to enchondromatosis alone, metachondromatosis carries an autosomal dominant inheritance.
Characterised by the pre...
Metachromatic leukodystrophy (MLD) is the most common hereditary (autosomal recessive) leukodystrophy and is one of the lysosomal storage disorders. It has characteristic imaging features including peri-atrial and to a lesser extent frontal horns leukodystrophy as well as periventricular periven...
The metaphyseal blanch sign of Steel is one of the signs seen on AP views of the adolescent hip indicating posterior displacement of the capital epiphysis.
It is a crescent-shaped area of increased density, that overlies the metaphysis adjacent to the physis on the AP radiograph. It is caused b...
Metaphyseal corner fractures, also known as classical metaphyseal lesions (CML) or bucket handle fractures, are observed in young children, less than 2 years old. It is considered pathognomic for non-accidental injury (NAI).
This injury is not only the fracture most specific for NA...
Metaphyseal dysplasia (also known as Pyle disease) is a rare autosomal recessive disorder characterised by flaring of the ends of long bones with relative constriction and sclerosis of the diaphysis and mild cranial sclerosis. It is one of the causes of an Erlenmeyer flask deformity. The flared ...
Meyer dysplasia (also known as dysplasia epiphysealis capitis femoris) is a fragmentation and delayed ossification of the femoral capital epiphyses that affects the paediatric hips. It is considered more of a normal hip developmental variation rather than a true dysplasia. It can be bilateral in...
MIBG scan is a scintigraphic study that uses metaiodobenzylguanidine labeled to Iodine-123 or Iodine-131. It is indicated in the investigation of phaeochromocytoma.
MIBG is positive in:
olfactory neuroblastoma 1
carcinoid tumour 4
Microcephaly is a descriptive term meaning a small head and is associated with numerous disorders of diverse aetiology. It is usually associated with microencephaly (small brain). For the purpose of this article the two will be used interchangeably.
As with most terms which describ...
Midface anomalies (craniofacial syndromes ) in children include
Treacher Collins syndrome
Midgut volvulus is a complication of malrotated bowel and results in a proximal bowel obstruction and ischaemia.
A midgut volvulus of malrotated bowel can potentially occur at any age but in approximately 75% of cases is within a month of birth 4,6, most within the first week 3, a...
Miller-Dieker syndrome (MDS) or is a rare chromosomal anomaly and is one of the conditions considered part of lissencephaly type I (classic) 6.
neuronal migrational anomalies: lissencephaly type I
prominent subarachnoid spaces
widened cerebral v...
Mineralising microangiopathy is a condition characterized by parenchymal cerebral calcifications, and is usually seen in children as a complication of cranial radiotherapy and chemotherapy 1-2.
Mineralizing microangiopathy can affect the brain widely, with typical sites i...
Möbius syndrome, also known as congenital facial diplegia syndrome, is a rare congenital condition characterised by the absence or underdevelopment of the abducens nerve (CN VI) and facial nerve (CN VII) nuclei.
Möbius syndrome is rare with an estimated incidence of ~1 case per 10...
Monteggia fracture-dislocations consist of a fracture of the ulnar shaft with concomitant dislocation of the radial head. The ulnar fracture is usually obvious, whereas the radial head dislocation can be overlooked, with potentially serious functional and medico-legal ramifications.
Morquio syndrome is an autosomal recessive mucopolysaccharidosis (MPS), type IV.
Incidence estimated at ~1:40,000.
Many cases present at ~2 years of age and have normal intelligence. Clinical features:
severe dwarfism (<4 foot)
Mucopolysaccharidoses (MPS) constitute a group of hereditary disorders, one of a number of lysosomal storage disorders, having in common an excessive accumulation of mucopolysaccharides secondary to deficiencies in specific enzymes (lysosomal hydrolases) responsible for degradation of mucopolysa...
Multicystic dysplastic kidney (MCDK) is a type of non-heritable paediatric cystic renal disease. It results in multiple cysts being formed in utero in the affected kidney.
Unilateral incidence is estimated at 1:2500-4000. There may be a predisposition for the left kidney, a slight...
Multicystic encephalomalacia (MCE) corresponds to a variant of encephalomalacia commonly seen in neonates in which numerous loculated lacy pseudocysts within the white matter and cortex are present as a result of an extensive brain insult.
It is a common feature observed in the neonatal hypoxi...
Multilocular cystic renal tumours (MCRT) are rare benign renal neoplasms occurring in a bimodal age distribution, involving young children and adults in the 4th and 5th decades.
For logical reasons, this article will discuss together the two ends of the spectrum of this disease, cystic partiall...
Multiple synostoses syndrome (SYNS), proximal symphalangism (SYM), tarsal-carpal coalition (TCC) syndrome, stapes ankylosis with broad thumbs and toes (SABTT), and brachydactyly B2 (BDB2) are overlapping autosomal dominant conditions united by typically displaying ankylosis of the proximal inter...
The mushroom sign (also called umbrella sign) is a radiological sign described in pyloric stenosis on barium examination.
This sign refers to the impression made by the hypertrophic pylorus on the duodenal cap.
cervix sign of pyloric stenosis
target sign of pyloric st...
The Mustard repair is a technique to correct transposition of the great arteries (TGA), and involves:
resection of atrial septum
creation of an atrial baffle with pericardium (or rarely synthetic material) 1
Transposition of the great arteries involves a discordance between the ven...
Nasal encephalocoeles are in most cases a form of neural tube defect particularly common in Southeast asia. They are are herniation of cranial content through a bony defect in the anterior skull base into the nasal area.
The term is variably used, but generally encompasses both frontoethmoidal ...
Nasal gliomas, also know as nasal glial heterotopia, are a rare congenital lesion composed of dysplastic glial cells which have lost their intracranial connections and present as an extranasal or intranasal mass.
Nasal gliomas are rare congenital lesions. These masses occur spora...