Johanson-Blizzard syndrome is a disorder of ectodermal dysplasia with wide variability in its manifestations. It is thought to have an autosomal recessive inheritance.
There is wide variability in the clinical presentation, but common features are:
low birth weight
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.
When associated with anomalies of the kidneys, liver and/or eyes then the term Joubert ...
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 for a J-shaped sella includes 1,2...
Juberg-Hayward syndrome (JHS), also known as the oro-cranio-digital syndrome, is a rare autosomal recessive syndrome characterized by the association of the following:
cleft lip and palate
minor vertebral and rib anomalies 4
horseshoe kidneys 4
Juvenile granulosa cell tumors of the ovary (JGCT) are a less common subtype of granulosa cell tumor of the ovary (~5% of cases). They are classified as ovarian sex cord / stromal tumors.
It typically occurs in premenarchal girls and young women. The mean age of presentation is 13...
Juvenile hyaline fibromatosis is a rare autosomal recessive syndrome outlined by painful, abnormal, often deforming deposits of hyalinized fibrous material in the extracellular matrix of the skin, subcutaneous soft tissues and gums. It is listed under fibroblastic and myofibroblastic tumors in t...
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.
The estimated incidence is ~13 per 100,000 per annum 3. By definition, symptoms must start ...
Staging of juvenile nasopharyngeal angiofibromas is performed with cross-sectional imaging and relies on the identification of local tumor extent, and invasion of adjacent spaces. For a discussion of this entity please refer to the parent article: juvenile nasopharyngeal angiofibroma.
Juvenile osteoporosis refers to osteoporosis occurring in children.
It can arise from a number of causes 1-4:
osteoporosis pseudoglioma syndrome
Juvenile polyposis syndrome, also referred as familial juvenile polyposis, is one of the polyposis syndromes and consists of hundreds of juvenile polyps.
Presentation in the second decade is most common 2.
Rectal bleeding, bowel obstruction and intussuscept...
Juvenile recurrent parotitis (JRP) is a form of recurrent inflammatory parotitis occurring in childhood.
JRP is considered the second most common cause of parotitis in childhood and commonly begins between 3 and 6 years of age.
Multiple episodes of parotid...
Kabuki syndrome (Niikawa-Kuroki syndrome) is a rare polydysplasia that is thought to be more common in Japan.
Estimated incidence of 1:32,000 in Japan. Sporadically seen elsewhere in the world. The reason for the disparity in incidence is controversial.
Kallmann syndrome is a rare genetic disorder characterized by hypogonadotropic hypogonadism associated with anosmia or hyposmia. When anosmia is absent, a similar syndrome is referred to as normosmic idiopathic hypogonadotropic hypogonadism.
It is a rare disorder with an estimate...
Kaposiform hemangioendothelioma is a rare, locally invasive vascular tumor that often presents in infancy, most commonly as an enlarging cutaneous mass 1,2.
Kaposiform hemangioendothelioma is a rare disease of childhood. The exact incidence and prevalence has not been accurately ...
Kaposiform lymphangiomatosis (KLA) is a rare lymphatic anomaly associated with a poor prognosis. Disease hallmarks include multifocal, intra- and extra-thoracic lymphatic malformations, thrombocytopenia and consumptive coagulopathy.
The exact prevalence and incidence of kaposiform...
Kartagener syndrome (also known as Kartagener-Afzelius syndrome) is a subset of primary ciliary dyskinesia, an autosomal recessive condition characterized by abnormal ciliary structure or function, leading to impaired mucociliary clearance.
The prevalence of primary ciliary dyski...
Kasabach-Merritt syndrome, also known as hemangioma thrombocytopenia syndrome, is a rare life-threatening disease found in infants in which a rapidly growing vascular tumor is responsible for thrombocytopenia, microangiopathic hemolytic anemia 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...
Kasai portoenterostomy is the surgery that comprises exposing the porta hepatis by radical excision of all bile duct tissue up to the liver capsule and attaching a Roux-en-Y loop of jejunum to the uncovered liver capsule above the bifurcation of the portal vein creating a portoenterostomy 1.
Kashin-Beck disease (KBD) is a rare chronic condition, comprising an osteochondropathy with a concurrent necrosis of the joints.
The disease has traditionally been endemic to areas of Tibet, China, North Korea, and Siberian Russia, and is usually diagnosed in pre-teenage children....
Kawasaki disease (KD) is a small to medium vessel vasculitis predominantly affecting young children. It can affect any organ but there is a predilection for the coronary vessels.
Japan has the highest incidence in the world, with an annual incidence of 300/100,000 children under t...
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 ...
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...
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.
A Kirner deformity, also known as dystelephalangy, is characterized by a curvature of the distal phalanx 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 bir...
Klinefelter syndrome (KS) is a sex chromosomal anomaly, which in most cases is characterized 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 te...
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.
There is a recognized female predilection 1. Klippel-Feil syndrome has an incidence of 1:40,000-42,...
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, which encodes for type II collagen (therefore clas...
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.
It typically presents in the pediatric population (4-6 years of age) and there is ...
Krabbe disease, also known as globoid cell leukodystrophy, is an autosomal recessive lysosomal storage disorder resulting in damage to cells involved in myelin turnover. It thus affects both the peripheral nervous system and the central nervous system (manifesting as a leukodystrophy).
Kump's bump, also known as the Kump hump, 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 fr...
Kwashiorkor is a condition characterized by bilateral edema caused by protein deficiency.
The largest population at risk for the condition are children who have begun weaning from breast milk or formula towards diets without sufficient protein. Therefore, kwashiorkor often affects...
Kyphomelic dysplasias (also known as "pseudocampomelia") is thought to be a heterogeneous class of "bent bone" skeletal dysplasias. Entities included in a differential for the class are:
congenital bowing of the long bones
cartilage-hair hypoplasia (CHH; metaphyseal dysplasia, McKusick type)
Kyphosis (plural: kyphoses), much less commonly kyphus, is a term used to describe the sagittal curvature of the thoracic spine.
An increased kyphotic angle is seen in the following conditions:
vertebral body fracture
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...
This article lists a series of labeled imaging anatomy cases by system and modality.
CT head: non-contrast axial
CT head: non-contrast coronal
CT head: non-contrast sagittal
CT head: angiogram axial
CT head: angiogram coronal
CT head: angiogram sagittal
CT head: venogram axial
Lacuna magna, also known as the sinus of Guérin, is a congenital blind-ended pouch located dorsal to navicular fossa of penis separated by fold and both share an external common opening to external urethral meatus. This diverticulum is located above and parallel to the urethra.
Ladd bands are the most commonly encountered form of peritoneal bands in disarrangement of intestines, e.g. intestinal malrotation.
Classically they extend from the abnormally positioned cecum to peritoneum and liver, crossing the duodenum in their course. Extension, however, can inc...
The Langenskiold Classification of Blount disease uses age and severity of deformity as grading parameters.
Six stage radiographic classification of infantile tibia vara, which is based on changes observed as the child matured:
stage I: 2-3 years
irregularity of metaphyseal os...
Langerhans cell histiocytosis (LCH) is a rare multisystem disease with a wide and heterogeneous clinical spectrum and variable extent of involvement.
Langerhans cell histiocytosis was previously known as histiocytosis X. The newer term is preferred as it is more descriptive of its...
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...
Laryngomalacia is the most common cause of noisy breathing in infants where it results in stridor. It is the result of a congenital abnormality of the cartilage in the larynx that results in the dynamic partial supraglottic collapse of the larynx during breathing.
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.
The lateral center-edge angle is a radiographic measurement of femoral head bony coverage by the acetabulum. It has since been shown superior to the extrusion index in measuring femoral head undercoverage.
It has primarily been described in assessing for acetabular dysplasia, but can al...
Lateral epicondyle fractures of the elbow 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.
These fractures are avulsion fractions of th...
The lateral finger view for pediatrics is part of a two view series examining the distal metacarpal, distal, middle and proximal phalanges of the finger of interest. The patient position can vary depending on which finger is being imaged.
This projection is useful for diagnosing f...
Lateral humeral condyle fractures also referred to simply as lateral condyle fractures (in the appropriate context), are relatively common elbow fractures that predominantly occur in children. They may be subtle but are hugely important to diagnose in a timely manner because if they are missed, ...
The lateral humeral line is used to confirm the alignment of the pediatric radiocapitellar joint in the coronal plane 1. This is particularly important in injuries such as a Monteggia fracture-dislocation or in a radial neck fracture.
The lateral humeral line is drawn on a pediatri...
Lead poisoning or plumbism is a multisystem condition due to the way in which lead interferes with the function of virtually every organ system. Plumbism most severely manifests due to its devastating effects on the CNS, but it also has important deleterious consequences on the skeletal, renal, ...
Leaky lung syndrome refers to a form of non-cardiogenic pulmonary edema.
Pulmonary edema due to increased capillary permeability.
Leaky lung syndrome is considered a mild form of a part of the spectrum of acute lung injury with ARDS at the other end of the s...
Left atrial enlargement (LAE) may result from many conditions, either congenital or acquired. It has some characteristic findings on a frontal chest radiograph. CT or MRI may also be used for diagnosis.
An enlarged left atrium can have many clinical implications, such as:...
Leg bowing in children is common and often developmental.
The differential includes:
exaggeration of normal age-related angulation changes at the knee
neonates and infants normally have varus angulation that gradually corrects within 6 months of w...
Legius syndrome is characterized by multiple café-au-lait spots, with or without freckles and macrocephaly.
More than 200 cases were reported between 2007 and 2013 1,3.
Although rare, it is estimated that up to 2% of patients fulfilling diagnostic criteria for neurofibromatosis-1...
Leigh syndrome, also known as subacute necrotizing 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...
Lennox-Gastaut syndrome is a form of refractory childhood-onset epilepsy and is often accompanied by developmental delay and psychological/ behavioral problems. An electroencephalogram (EEG) often shows a slow spike and wave pattern.
It often appears between the 2nd and 6th years ...
Lenticulostriate vasculopathy also known as thalamostriate vasculopathy or mineralizing vasculopathy 1, refers to the ultrasound appearance of hyperechogenic linear or branching tubular streaks in the thalami or basal ganglia of neonates.
Lenticulostriate vasculopathy has been rep...
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.
Lesch-Nyhan syndrome is a rare X-linked genetic disease caused by a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT).
Affects 1 per 380,000 individuals, which are nearly all male given the X-linked inheritance 1.
Lethal omphalocele-cleft palate syndrome is, as the name suggests, characterized 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 a heterogeneous group of disorders that primarily affect the white matter of the central nervous system. They are particularly encountered in childhood as many are genetically determined and represent abnormalities in white matter metabolism. A number of leukodystrophies...
Leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (LBSL) is a rare inherited autosomal recessive leukodystrophy characterized by slowly-progressive pyramidal, cerebellar, and dorsal column dysfunction.
Although considered rare, the exact prevalen...
Leukoencephalopathy with calcification and cysts, also known as Labrune syndrome, is a rare condition that consists of a triad of leukoencephalopathy, cerebral calcification and edematous cysts.
Leukoencephalopathy with calcification and cysts is an extremely rare condition, with ...
The Levene index is the distance between the falx and the lateral wall of the anterior horn in the coronal plane at the level of the third ventricle.
It is useful as a marker of ventricular volume and thus has been proposed as a helpful biomarker in the diagnosis of hydrocephalus1.
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); hypernatremia, hypokalemia and elevated serum bicarbonate. Typically patients are asymptomatic other than ...
The ligamentum venosum is a fibrous remnant which travels superiorly from the porta hepatis of the liver to the inferior vena cava. It is often obliterated in adults.
In the fetus, it is patent and known as the ductus venosus which shunts blood returning from the placenta in the umbilical vein...
A limbus labrum is as an enlarged and deformed acetabular labrum, which covers the lateral margin of a subluxed femoral head.
Seen in children and young adults.
hip pain and labral tears
seen mainly in settings of developmental dysplasia of the hip (DDH) o...
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 in adolescents. The line should normally intersect the lateral part of the superior femoral epiphysis. If the line of Klein fails to intersect the...
Neonatal lines and tubes are widely used in the NICU (neonatal intensive care unit) in the management of critically ill neonates. Examples include:
nasogastric (NG) tube
endotracheal (ET) tube
central venous line
umbilical artery catheter
umbilical vein catheter
The NG tu...
Lipoblastoma is a rare, benign, encapsulated tumor arising from embryonic white fat.
It occurs primarily in infancy and early childhood (more than 90% before age 3 years).
May present as a rapidly enlarging mass 4. It most often occurs in the extremities an...
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...
Lipofibromatosis refers to a rare unspecified/borderline slow-growing soft tissue tumor prone to recurrence, which is often found in the hands and feet of children.
Infantile or juvenile fibromatosis variant is an alternative term, which has been used but is now discouraged 1.
Lipomyelocele, also known as lipomyeloschisis, is one of the most common closed spinal dysraphism. It is seen in the thoracolumbar region and usually presents as a fatty subcutaneous mass.
It is twice as common as lipomyelomeningocele.
Affected individuals are usually as...
Lipomyelomeningoceles are one of the forms of closed spinal dysraphism. They usually present as a subcutaneous fatty mass just above the intergluteal cleft. However, some lipomyelomeningoceles may occur at other locations along the spinal canal.
Lipomyelomeningoceles may ...
The lissencephaly-pachygyria spectrum is a useful way to describe 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 malf...
Lissencephaly type II is characterized by reduction in normal sulcation, associated with a bumpy or pebbly cortical surface (thus the term cobblestone lissencephaly), absent in lissencephaly type I. Unlike type I lissencephaly which is the result of neuronal undermigration, type II is due to ove...
Lissencephaly type I, also known as classic lissencephaly, is a heterogeneous group of disorders of cortical formation characterized by a smooth brain, with absent or hypoplastic sulci and is strongly associated with subcortical band heterotopia (see classification system for cortical malformati...
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 deceased fetus is too large to be re-abs...
Little league shoulder is thought to occur due to overuse damage of the proximal humeral epiphysis/metaphysis, seen typically in young baseball players, especially pitchers.
Although it is most commonly seen in baseball players particularly in pitchers, it also presents in adolesc...
Pediatric liver lesions are a heterogeneous group that includes infiltrative lesions and those that demonstrate mass-effect. Moreover, they may be solitary or multiple, benign or malignant:
benign liver tumors
malignant liver tumors
There are differing frequencies of both benign...
Lobar holoprosencephaly is the least severe of the classical subtypes of holoprosencephaly (HPE), characterized 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 is an autosomal dominant connective tissue disorder which has many features similar to Marfan syndrome.
The disease is characterized by skeletal manifestations and vasculopathies. Although Loeys-Dietz syndrome shares many similarities with Marfan syndrome, the course is oft...
Looser zones, also known as cortical infractions, Milkman lines or pseudofractures, are wide, transverse lucencies with sclerotic borders traversing partway through a bone, usually perpendicular to the involved cortex, and are associated most frequently with osteomalacia and rickets.
Lordosis (plural: lordoses) is the term used to refer to the normal anterior curvature of the cervical and lumbar spines when viewed from the side (concavity at the posterior aspect of the spine (cf kyphosis). Lordosis cervicis and lordosis lumbalis are the respective Terminologia Anatomica term...
Lowe syndrome, also known as the oculocerebrorenal syndrome of Lowe, is a multisystem disorder characterized by anomalies primarily affecting the eyes, nervous system, and kidneys.
It is an extremely rare, pan-ethnic disease, with an estimated prevalence in the general population ...
Lückenschädel 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 u...
Lumbar Scheuermann disease is a type of variant Scheuermann disease where there is no abnormal kyphosis. This has been reported in the lumbar spine and thoracolumbar junction of patients of all ages, and back pain may be present.
On imaging, affected individuals can have vertebral endplate chan...
LUMBAR, PELVIS, or SACRAL syndrome is the association of infantile hemangiomas in the lower body with other extracutaneous congenital abnormalities in the region. The syndrome may be incomplete.
lower body hemangiomas
urogenital anomalies and ulceration
A mnemonic to remember the diagnostic criteria of lymphangioleiomyomatosis (LAM) is:
T: tuberous sclerosis
H: HRCT characteristic or compatible lung findings of LAM
RA: renal angiomyolipoma
L: lymphatic malformations
L: lung biopsy-proven LAM
Lymphatic malformations are benign lesions of vascular origin that show lymphatic differentiation. Specifically, they are vascular malformations and not vascular tumors as per the 2018 ISSVA classification of vascular anomalies 5.
This article focuses on the general features of lymphatic malfo...
Lysosomal storage disorders (LSDs) form a large group of clinical entities, more than forty now described, with the common etiological theme being the presence of dysfunctional lysosomal proteins, with the secondary accumulation of toxic metabolites inside the cellular lysosomes.
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
Macrodactyly is a descriptive term for isolated enlargement of some or all elements of a digit, whether of the hand or foot 1. Often it is equated with its most common cause, macrodystrophia lipomatosa 4. Rarely it can be seen as a form of Proteus syndrome 2
A number of conditions may manifest ...