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 leukodystrophy.
Can vary and depends on the 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...
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)
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 labelled 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
MR head: T2 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...
Langerhans cell histiocytosis (LCH) is a rare multi-system 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's 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 primarily been described in assessing for acetabular dysplasia but can also be used in femoroacetabular impingement.
It is calculated on AP pelvic radiographs by using drawing a b...
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 pediatric age group (6-...
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, ...
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 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...
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 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 is thought to often appear between the 2nd a...
Lenticulostriate vasculopathy also known as thalamostriate vasculopathy or mineralising 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.
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 genetically determined white matter disorders characterized by abnormal myelin formation (dysmyelinating disorders) and or abnormal break down of myelin (demyelinating disorders) which typically, although not invariably, affect children. They inc...
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 calcifications and cysts, also known as Labrune syndrome, is a rare condition that consists of a triad of leukoencephalopathy, cerebral calcifications and edematous cysts.
Leukoencephalopathy with calcifications and cysts is an extremely rare condition, wi...
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...
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...
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). It most often occurs in the extremities and trunk, although it can be seen in other areas 1. The entity was originally described...
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%)...
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...
Pediatric 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 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 (LDS) 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 ...
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 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...
Lymphangiomas are benign lesions of vascular origin that show lymphatic differentiation. It is considered the lymphatic equivalent of a hemangioma of blood vessels.
This article focuses the general features of lymphangiomas. For a specific discussion in other locations, please refer to the art...
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
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, macrosomia, and limited gigantism 3.
It is worth noting that m...
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...
Pediatric malignant liver tumors are rare, some of which occur only in children but that are similar to those that occur in adults.
Malignant liver tumors account for ~1% of pediatric malignancies 2.
Broadly, any malignant liver mass can be defined as a metastasis or p...
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.
MSUD occurs in 1 in 185,000 births 9.
It usually ma...
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 a wider clinical spectrum.
failure to thrive
The mastoid or posterolateral fontanelles (or fontanels) are paired bilateral soft membranous gaps at the junction of the parietomastoid, occipitomastoid, and lambdoid sutures. Each mastoid fontanelle persists until the second year of life, after which it is known as the asterion. It can be used...
Mayer-Rokitansky-Küster-Hauser syndrome (MRKH) is a congenital anomaly characterized by vaginal agenesis associated with, in the majority of cases, a spectrum of other genitourinary tract abnormalities. MRKH syndrome belongs to class I Mullerian duct anomalies.
Two different forms are described...
McKusick Kaufman syndrome (MKS) is an autosomal recessive multiple malformation syndrome primarily characterized by
hydrometrocolpos - vaginal atresia
congenital heart disease
Measles is a highly contagious infection caused by the measles virus.
The measles vaccine, first introduced in 1963, has significantly reduced the incidences of measles. However, it remains endemic in countries with low vaccination rates 1. Worldwide, it is the leading cause of va...
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 characterized 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, often in term or post-term infants.
Up to 10-15% of live births after 34 weeks can present with meconium stained fluid but only 1-5% of neonates de...
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 pediatric 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 tumor 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 ...
Megalencephalic leukoencephalopathy with subcortical cysts, also known as Van der Knaap disease, refers to a rare inherited autosomal recessive disease characterized by diffuse subcortical leukoencephalopathy associated with white matter cystic degeneration.
The age at symptoms m...
Megalencephaly-capillary malformation (MCAP) syndrome, also known as macrocephaly-capillary malformation syndrome, is a rare and well described genetic disorder caused by somatic mutations in the PIK3CA gene on chromosome 3q26 and characterized by early brain overgrowth and body morphogenesis an...
Megapolycalycosis is a rare congenital anomaly of the kidney which is characterized by dilatation and increase in number of the renal calyces without any distal obstruction.
Schinzel- Giedion syndrome
Melanotic neuroectodermal tumor of infancy (MNTI) is a rare pigmented tumor that primarily affects the calvaria or facial skeleton of children, typically during infancy. It is usually a benign tumor, albeit locally aggressive.
Most cases are diagnosed during infancy, usually withi...
The mendosal suture (also known as the accessory occipital suture) is a normal calvarial suture.
The suture extends through the occipital bone, lying superior to the occipitomastoid suture and inferomedial to the lambdoid suture. It closes in utero or in the first few days of lif...
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-dependent mitochondrial enzymes.
A mesenchymal hamartoma of the chest wall is a very rare benign chest wall tumor. It is sometimes classified as a non-neoplastic developmental anomaly rather than a tumor.
They typically present in neonates or infants 1-3.
Many present with a chest wall mas...
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.
Characterized 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 (a.k.a. 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 ...
Metaphyseal chondrodysplasia (also known as metaphyseal dysplasia or dysostosis) is a type of skeletal dysplasia.
Schmid type - mild type, due to mutation in type X collagen (COL10A1 gene), metaphyses are cupped resembling rickets
Pena and Vaandrager type - intermedi...
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 suggestive of non-accidental injury (NAI).
This injury is not only the fracture most specific for NAI, it is al...
Metaphyseal dysplasia (also known as Pyle disease) is a rare autosomal recessive disorder characterized 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 pediatric 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 tumor 4
Microcephaly is a descriptive term meaning a small head and is associated with numerous disorders of diverse etiology. 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 describe...
Midaortic syndrome is an uncommon entity affecting children and young adults. It is characterized by progressive narrowing of the abdominal aorta and its major branches.
The onset of symptoms is usually during childhood or young adulthood 2:
hypertension (most common)
Midface anomalies (craniofacial syndromes ) in children include
Treacher Collins syndrome
Midgut volvulus is a complication of malrotated bowel. It may result in proximal bowel obstruction with resultant ischemia if prompt treatment is not instigated.
A midgut volvulus of malrotated bowel can potentially occur at any age but in approximately 75% of cases occur within 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...
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...