PAEDIATRICS 3 Flashcards
Croup: - age? - cause?
6 months - 3 years - parainfluenza
Epiglottitis - age? - cause? - cause of death?
3.5 years old, also teens - H. influenzae - asphyxiation from aryepiglottic flods
exudative tracheitis: - age? - cause?
- 6-10 years - staph A
most common soft tissue mass in trachea
subglottic hemangioma
PHACES syndrome
- Posterior fossa (DWM) - Hemangiomas - Arterial anomalies - Coarctation of aorta/cardiac defects - Eye abnormalities - Subglottic hemangiomas
retropharyngeal soft tissues: normal thickness
6 mm at C2 22 mm at C6
Infantile vs. congenital hemangiomas
- infantile are not present at birth; show up around 6 months and nearly always involute - congenital are present at birth and may or may not involute
neonatal pneumonia -GBS vs. non GBS
- low lung volumes for GBS - other pneumonias have high lung volumes - GBS pneumonia less likely to have pleural effusion than non-GBS
Neonatal pneumonia
Dr Daniel J Bell◉ and Dr Aditya Shetty et al.
Neonatal pneumonia refers to inflammatory changes of the respiratory system caused by neonatal infection.
Epidemiology
It is one of the leading causes of significant morbidity and mortality in developing countries. Neonatal pneumonia accounts for 10% of global child mortality. At the time of writing it is thought to account for 750,000 to 1.2 million neonatal deaths annually 5.
Risk factors
Exposure to these organisms occurs in the following cases:
rupture of membranes more than 6 hours before delivery
prolonged and complicated labours
premature infants
immune disorder
Clinical presentation
Neutropenia with temperature instability.
Signs and symptoms include:
tachypnoea
chest recession
apnoea
respiratory distress
cough (absent in two-thirds of the cases) 7
Pathology
Aetiology
Occurs with transplacental spread. Aspiration of infected amniotic fluid after prolonged rupture of membranes or during delivery.
Agents
Maternal systemic infection:
rubella
cytomegalovirus
Treponema pallidum
Listeria monocytogenes
tuberculosis
HIV
COVID-19
Most commonly isolated bacteria include:
Streptococci (group A and B)
Staphylococcus aureus
E. coli
Klebsiella
Proteus spp.
Classification
early onset
occurs in the first week of life and as an intrauterine pneumonia
often caused by group B streptococcus or gram negative bacteria
late onset
occurs in subsequent three weeks
often caused by gram positive bacteria
Radiographic features
Plain radiograph
Broad and wide spectrum of abnormalities varying from a normal chest, localised or diffuse alveolar densities, reticular opacities and features similar to respiratory distress syndrome.
The most frequent and characteristic alveolar pattern is dense bilateral air space filling process with numerous air bronchograms.
Complications of respiratory therapy like interstitial emphysema, pneumomediastinum and pneumothorax may also be identified.
Treatment and prognosis
Management usually comprises a similar strategy to neonatal sepsis with antimicrobial therapy. The risk of mortality is heavily reliant on birth weight and age of onset; low birth weight 8 and early onset 6,7 being associated with more fatality.
Differential diagnosis
respiratory distress syndrome
granular densities with air bronchograms
usually no associated pleural effusion
transient tachypnoea of the newborn (TTN)
serial radiographs help differentiate TTN from pneumonia as pneumonia would persist beyond 1-2 days which is the usual duration of TTN
See also
neonatal respiratory distress (causes)
Quiz questions
PIE - timeline - buzzword - treatment - warning sign for? - what is a mimic?
- occurs in 1st week - linear lucencies - PIE side down position - warning sign for impending pneumothorax - mimic is surfactant replacement therapy
classic appearance for papillomatosis
multiple lung nodules with cavitation - 2% risk for squamous cell cancer
pleuropulmonary blastoma - typical location - calcification? - rib invasion?
- right sided and pleural based - no calcification or rib invasion - 10% have a multilocular cystic nephroma - cystic type occurs in kids < 1 year old and tend to be more benign
most common mass in masticator space of kid
rhabdomyosarcoma
most common extra-ocular, intra-orbital malignancy in children
rhabdomyosarcoma
most common benign orbital mass in child
dermoid
differential for high lung volumes in neonate
- meconium aspiration - non GBS neonatal pneumonia
differential for low to normal lung volumes in neonate
- surfactant deficiency - GBS neonatal pneumonia
Transient tachypnea - risk factors - time course -radiographic appearance
- maternal sedation, C-section, maternal DM - starts at 6 hrs, peaks at 1 day, resolves by 3 days - coarse intersitial markings with fluid in fissure - normal to high lung volumes
risks of surfactant replacement therapy? - was does it mimic
- pulmonary hemorrhage - increased risk of PDA - can cause bleb like lucencies - mimics PIE
Thymic rebound
- FDG avid - drops out on opposed phase MRI
pulmonary slings - associations
- tracheal stenosis - compelte tracheal rings - imperforate anus - TE fistula - horseshoe lung - hypoplastic lung
Aberrant left pulmonary artery
Dr Mostafa El-Feky◉ and Dr Hani Makky Al Salam et al.
Aberrant left pulmonary artery, also known as pulmonary sling, represents an anatomical variant characterised by the left pulmonary artery arising from the right pulmonary artery and passing above the right main bronchus and in between the trachea and oesophagus to reach the left lung. It may lead to compression and focal stenosis of the trachea.
Epidemiology
Associations
Other anomalies that can be associated with aberrant left pulmonary artery are:
head and neck
absent thyroid isthmus
thoracic
complete tracheal rings
tracheal stenosis
single lobed left lung
bilobed right lung
congenital lobar overinflation 5
abdominopelvic
imperforate anus
Hirschsprung disease
intestinal malrotation
agenesis of left kidney and ureter
agenesis of gallbladder
musculoskeletal
fusion of third and fourth lumbar vertebrae
diaphragmatic hernia
Clinical presentation
Respiratory distress predominates over oesophageal symptoms, usually presenting early in the neonatal period.
Pathology
Pathogenesis
Aberrant left pulmonary arteries are thought to arise from a failure of formation of the 6th aortic arch. They have an anomalous origin from the posterior wall of the right pulmonary artery before coursing to the left lung passing posterior to the trachea and anterior to the oesophagus.
The term “sling” is best used when the proximal portion of the anomalous vessel impinges on the right main bronchus and causes air trapping of the entire right lung, or right middle or lower lobes.
The second type of aberrant left pulmonary artery, which often is fatal, is associated with long-segment tracheal stenosis. This kind of tracheal stenosis is due to complete tracheal rings.
Radiographic features
Plain radiograph
Conventional radiographs obtained in neonates at birth may show fetal fluid retention or air, with a mediastinal shift usually to the left side.
In adults, a left-sided deviation of the trachea and an anterior bowing of the right main stem bronchus may be seen. In cases of ring sling complex, radiographs often show an absence of unilateral pulmonary aeration.
Fluoroscopy
In most instances, the barium oesophagogram characteristically shows a mass between the trachea and the oesophagus just above the level of the carina, usually seen as an anterior indentation over the oesophagus.
CT/MRI
The main bronchi have horizontal courses (i.e. low T-shaped carina), and vascular anatomy is normally well delineated on CT or MR angiography. Atelectasis may be seen in the upper lobes.
Treatment and prognosis
Repositioning of the artery usually reverses compression, particularly when the underlying tracheobronchial tree is normal.
The mortality rate is high in patients requiring tracheal reconstruction because the stenosis is primary and not due to the vessel.
The success of reconstructive procedures in the rigid trachea can be studied by using three-dimensional CT techniques such as virtual bronchoscopy.
Practical points
it is the only vascular ring to pass between the trachea and oesophagus
it compresses the trachea posteriorly and causes anterior impression over the oesophagus on lateral radiographs
Ladd’s procedure
- procedure done to prevent midgut volvulus - Ladd’s bands are divided - appendix is removed - small bowel ends up on the right and large bowel ends up on teh eltq
Pyloric stenosis - age range - criteria - clinical sign
- 2-12 weeks (peaks 3-6 weeks) - 4 mm single wall; 14 mm length - paradoxical aciduria
differential for long microcolon
- meconium ileus - distal ileal atresia - contrast does not reach ileal loops - total colonic aganglionosis can mimic microcolon
intussusception - time frame - size criteria - classic lead points
- 3 months - 3 years - > 2.5 cm - Meckel’s, HSP vasculitis, enteric duplication cysts
air reduction for intussusception - pressure limit - contraindications - success rate - risk of perforation
- 120 mm Hg - peritonitis, free air - 80-90% - 0.5% risk of perforation
VACTERL
vertebral anomalies anal (imperforate) Cardiac (73%) TE fistula Renal limb (radial ray)
when is physiologic gut herniation seen
6- 8 weeks
omphalocele - most common associated chromosomal abnormality? - other associations
- Trisomy 18 - umbilical cord cysts, Turners, Klinefelters, Beckwith Wiedeman, cardiac defects
Schwachman Diamond syndrome
- # 2 cause of pancreatic insufficiency in kdis - diarrhea, short stature, and eczema
liver tumors age 0-3
- hepatoblastoma - infantile hepatic hemangioma - mesenchymal hamartoma
Infantile hepatic hemangioma
- often < 1 yr - high output CHF - skin hemangiomas present in 50% - Endothelial growth factor is elevated - spontaneously involute without therapy - prgoressively calcify - can be associated with Kasabach- Merritt syndrome
Hepatoblastoma
- most common primary liver tumor of childhood (< 5) - assocaited with hemihypertrophy, Wilms, Beckwith Wiedemann - prematurity is risk factor - elevated AFP - solitary right sided mass - can extend into PV, HV, and IVC - calcification present in 50% - may cause precocious puberty from making beta-HCG
Hepatic Mesenchymal hamartoma
- predominantly cystic mass -
- calcification UNCOMMON -
- large portal vein branch feeding tumor -
- AFP is negative
Hepatic mesenchymal hamartoma
Dr Mohamed Saber and Dr Yuranga Weerakkody◉ et al.
Hepatic mesenchymal hamartomas are uncommon benign hepatic lesions which are mostly seen in children under the age of 2. Some authors consider them to be developmental anomalies rather than cystic neoplasia 9,12.
Epidemiology
Hepatic mesenchymal hamartomas typically occur in children and neonates 3 with most cases presenting within the first two years of life 3. They rarely present in adults 10. There is a reported male predominance of 2:1 13.
Clinical presentation
Hepatic mesenchymal hamartoma can be rather large on presentation, and so abdominal enlargement and respiratory distress are thought to be the most common presenting features in children.
Classically presents with normal serum alpha-fetoprotein (AFP) level, although unusual cases presenting with elevated AFP have been reported 2.
Pathology
The lesions are characterised by an admixture of ductal structures (blood vessels, small groups of hepatocytes, and bile ducts) within a copious loose/oedematous connective tissue stroma 7-8. They rarely calcify 15.
On a cut surface, there are typically multiple cysts in an oedematous stroma; the cysts can vary in size ranging from a few millimetres to 16 cm, and in number and distribution, being discrete or connected 13.
Histology
Mesenchymal hamartomas in adults may show a series of histologic modifications: progressive loss of hepatocytes, degeneration of bile duct epithelium, and cystic changes of the mesenchymal component 12-13.
Genetics
Mesenchymal hamartomas of the liver are attributed to abnormal expression of the chromosome 19 microRNA cluster, such as due to chromosome rearrangement, or DICER1 gene mutation, which in turn causes microRNA dysregulation 14.
Radiographic features
As with other hamartomas, hepatic mesenchymal hamartomas are disorganised lesions that are usually cystic with a variable amount of associated soft tissue. A wide spectrum of imaging features has been described, from cystic and often multiseptated, to mixed solid/cystic, to even completely solid 1.
The dominant radiographic pattern, however, is a large (often around 12-15 cm 8), predominantly cystic mass with internal septations 3. There can be considerable variation in the size of septae and cystic spaces 9.
Conventional radiograph
Although nonspecific, radiographs may show a large, non-calcified mass in the right upper quadrant 9.
Ultrasound
It usually appears as a multiseptated cystic lesion interspersed with solid components. Detection is difficult for pedunculated lesions. In some lesions may be the predominance of solid structures 13.
CT
On unenhanced CT, it usually has a heterogeneous appearance. The stromal elements often appear hypoattenuating, whereas the cystic components have water attenuation 8-9. The appearance of cystic and solid portions has been likened to Swiss cheese.
On a postcontrast CT scan, solid portions or thick septa of the tumours can show heterogeneous enhancement 1-8,13.
MRI
prominent cystic components
multifocality is uncommon
MR imaging appearance of mesenchymal hamartoma can also vary depending on the presence of stromal elements as well as the protein content of the fluid 8.
Angiography (DSA)
While not being a standard diagnostic imaging modality of choice, angiography may show peripheral hypervascularity to the lesion with a septated avascular centre 3-9.
Treatment and prognosis
Mesenchymal hamartomas are benign lesions and are best treated by surgical resection, which usually results in cure 2. There are occasional reports of ultrasound-guided intraoperative aspiration of fluid from the cystic components of the tumour to reduce its volume, facilitating surgical resection 5.
Complications
There are fatal complications associated with hepatic mesenchymal hamartomas (particularly in the prenatal group) that generally result from the size of lesion 2:
fetal hydrops
respiratory distress: neonatal respiratory distress
circulatory complications/compromise owing to a large space-occupying abdominal lesion
Differential diagnosis
On imaging consider
hepatic abscess
hepatoblastoma: often predominance of the solid component and persistently elevated or rising AFP
undifferentiated (embryonal) sarcoma of the liver: older age at presentation (6-10 years)
infantile haemangioendothelioma of the liver
simple hepatic cyst (or cluster): no solid component
undifferentiated embryonal sarcoma of the liver
- pissed off cousin of mesenchymal hamartoma
- cystic but much more aggressive
- septations and pseudocapsule
- Occurs in older age group than Hepatic mesenchymal haemangiomas most commonly between 6 and 10 years of age,
Undifferentiated embryonal sarcoma of the liver
Dr Henry Knipe◉◈ and Dr Oscar Osorio et al.
Undifferentiated embryonal sarcomas of the liver are rare, aggressive, and malignant liver tumours encountered in the paediatric population.
Epidemiology
Approximately 90% of cases occur in patients under 15 years of age, most commonly between 6 and 10 years of age, but some cases have been reported in adults 1. There is a slight male predominance, but no racial predilection 1.
Although it is a rare tumour, the undifferentiated embryonal sarcoma of the liver is considered by some studies as the third most common liver primary malignancy of childhood, after hepatoblastoma and hepatocellular carcinoma 2.
Clinical presentation
It usually manifests as a large abdominal mass, with or without abdominal pain or discomfort 1,3. Additional clinical features include fever, weight loss, lethargy and respiratory distress 1,3. Acute onset of symptoms are reported in cases of rupture, but this is uncommon 1.
Liver function test results can be normal or show slightly elevated transaminase levels 1,2. Importantly, alpha-fetoprotein (AFP) and CA-125 levels are normal 1,2.
Pathology
Some authors have considered this as the malignant counterpart of the hepatic mesenchymal hamartoma, because there have been reports of malignant transformation of those benign tumours; however, there is currently no strong evidence to support that hypothesis 1.
Location
About 75% of cases occur in the right lobe of the liver 3,4. Metastases, when seen, are most frequently found in the lungs, pleura, peritoneum and bone 1.
Macroscopic appearance
This tumour is usually a single and well-circumscribed lesion, with a large size (often >10 cm), and has both cystic and solid elements 3,4. Cross-section specimens of the tumour show a grey-white heterogeneous appearance, with areas of haemorrhage and necrosis, as well as gelatinous areas due to myxoid matrix 3,4.
Microscopic appearance
A fibrous pseudocapsule separates the lesion from the surrounding parenchyma 1. Clusters of hepatocytes are seen at the margins of the tumour, including within the pseudocapsule 1,4. The solid component is made up of spindle-like cells with ill-defined borders, and overall, has a sarcomatous appearance 1,4. Mitotic figures are very frequently seen, as well as eosinophilic globules in the cytoplasm ad hyperchromatic multiple nuclei 1,4.
Radiographic features
A large mass located in the right lobe of the liver in a paediatric patient under 15 years should raise the suspicion of an undifferentiated embryonal sarcoma of the liver, especially if it has a significant necrotic or cystic component and the patient has normal AFP levels 1. Vascular characteristics are non-specific, and range from hypo- to hypervascular.
Generally, a unique radiographic characteristic of this tumour is the predominantly solid appearance on ultrasound, but predominantly cystic appearance on CT and MRI 1,5.
Plain radiograph
A plain radiograph is usually of limited use but may show a large non-calcified abdominal mass at the level of the liver 2.
Ultrasound
Findings described include 1:
heterogeneous, predominantly solid-appearing liver mass
mainly iso- or hyperechogenic to the normal liver parenchyma
necrotic/cystic areas, represented by anechoic or hypoechogenic zones with posterior acoustic enhancement
CT
Findings described include 1:
a large hypodense mass, most commonly (75%) located in the right lobe of the liver, with solid elements and multiple hyperdense septa
predominantly fluid attenuation (more than 80% of the total volume) due to the myxoid stroma
heterogeneous enhancement is seen, especially in the delayed contrast phase, around the periphery (including rim enhancement of the pseudocapsule) and the septa
CT is often not sensitive enough to detect the regions of haemorrhage within the tumour 1.
MRI
The tumour itself has the following signal characteristics 1:
T1: hypointense
T2: hyperintense
T1 C+ (Gd): heterogeneous enhancement
Additionally, there may be focal areas within the tumour of hyperintensity on T1-weighted images and hypointensity on T2-weighted images, which correlate with regions of haemorrhage 1.
The surrounding pseudocapsule has the following signal characteristics 1:
T1: hypointense
T2: hypointense
Treatment and prognosis
Treatment consists of complete tumour resection with a chemotherapy regimen 1,5.
Although prognosis was once quite poor, with the aid of new multimodal treatment the survival rates are improving, with most of the cases currently considered curable 5.
History and etymology
The term “undifferentiated embryonal sarcoma” was first proposed and used by J Thomas Stocker and Kamal G Ishak, American physicians, in 1978 3.
Differential diagnosis
hepatic mesenchymal hamartoma (younger patients)
hydatid cyst (in endemic areas)
hepatic abscess (clinical evaluation)
cystic degeneration in hepatoblastoma or hepatocellular carcinoma (rare; elevated AFP)
cystic metastases (rare in children)
Hepatic pediatric tumors in child > 5 yrs
- HCC
- fibrolamellar HCC
- calcifies more often
- Fibrolamellar hepatocellular carcinoma is a distinct variant of HCC
- not associated with cirrhosis and has different demographics and risk factors.
- fibrolamellar HCC
- undifferentiated embryonal sarcoma
Alagille syndrome
- peripheral pulmonary stenosis
- paucity of intrahepatic ducts
biliary atresia
- absence of extrahepatic ducts with the proliferation of intrahepatic ducts
- association with trisomy 18 and polysplenia
- gallbladder may be absent
- Kasai procedure prior to 3 months
- triangle cord sign
- near portal vein
- no tracer excretion into bowel at 24 hrs
Right sided heterotaxia
- 2 fissures in left lung - asplenia - reversed Aorta/IVC - more cardiac malformations
Caffey disease
- self-limiting soft tissue welling,
- periosteal reaction -
- first 6 months of life -
- hot mandible on bone scan (mandible is most common location)
- Have you ever seen that giant multiple volume set of peds radiology books? Yeah. Same Guy. This thing is a self limiting disorder of soft tissue swelling, periosteal reaction, irritability seen within the first 6 months of life.
- Really hot mandible onbone scan.
- The mandible is the most common location
- Clavicle and ulnar are the other classic sites.
- Its rare as hell’
Caffey disease
Dr Jeremy Jones◉ and Dr Paresh K Desai et al.
Caffey disease or infantile cortical hyperostosis is a largely self-limiting disorder which affects infants. It causes bone changes, soft-tissue swelling, and irritability.
It is distinct from physiological periostitis which can be seen involving the diaphyses of the tibiae, humeri, and femora at the same age.
A rare variant known as prenatal onset cortical hyperostosis is severe and fatal, though it is probably a separate entity altogether 1.
Clinical presentation
Children usually present within the first five months of life with tender and painful soft tissue swelling, erythema, fever, and irritability.
Pathology
Caffey disease is a type I collagenopathy. Both familial and sporadic forms exist. There is evidence to suggest that the familial form is inherited in an autosomal dominant fashion with incomplete penetrance and variable expression 2,3.
Location
The flat bones are most commonly affected:
mandible: in 75-80% of cases
clavicles
scapula: 10% of cases
ribs: lateral aspect; ipsilateral pleural effusion may appear
calvaria
ilia
The ulnae are the long bones most commonly affected.
Lytic skull lesions have been reported.
The carpus, tarsus, phalanges and vertebral bodies are rarely involved.
Markers
Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and alkaline phosphatase (ALP) levels are often elevated. The combination of the clinical picture, lab findings, and imaging findings is sufficient for a diagnosis.
Phases
Early, subacute, and late pathologic phases have been described, each with its accompanying radiologic features:
Early (acute)
characterised by periostitis
the inflammatory process may extend to adjacent soft tissues
cortical resorption may occur
Subacute
inflammation subsides
periosteal thickening, with subsequent ossifying periostitis
immature lamellar bone is deposited in layers under the periosteum, sometimes exuberantly
osseous deposition may occur in adjacent soft tissues
Late
removal of peripheral bone, from inner to outer surface
may produce a thin-walled bone with a large medullary cavity in long-standing cases
cortical remodelling may also occur
Long-term sequelae
mandibular asymmetry and/or undergrowth
persistent synostosis of the ribs: could cause scoliosis
persistent synostosis of bones of the forearms and legs
bowing of long bones
leg length discrepancy
disease recurrence in childhood
Radiographic features
Plain radiograph
May show all or some of the following 4:
periosteal reaction, either single-layered or lamellated
subperiosteal cortical hyperostosis
dense laminated subperiosteal new bone formation
marked increase in cortical width and density
in the involved long bones, only the diaphysis is affected, sparing the metaphysis and epiphysis; consequently, the bone becomes spindle-shaped
soft tissue swelling over the involved bones
the mandible, clavicle, and ribs are most often affected, particularly in sporadic cases
Radiographic evidence of the disease may persist for years after resolution of clinical symptoms.
Ultrasound
Can identify soft tissue oedema and early periosteal new bone formation. High-frequency transducers should be used.
MRI
Can show periostitis and soft tissue oedema. It should be stressed that MRI usually does not offer much added-value in advancing the diagnosis 5 unless infection or neoplasia are high on the differential list; indeed, at times, MRI appearance may confound the radiologist. Hence, radiography should be the primary modality of investigation and follow-up.
Nuclear imaging
During the active phase of the disease, there is markedly increased radiotracer uptake in the involved bones, both on bone and gallium (Ga-67) scans. The “bearded infant” appearance refers to intense radiotracer uptake in the mandible 6.
Nuclear scans can also be useful for showing the extent of skeletal involvement.
Treatment and prognosis
As noted above, Caffey disease is self-limiting and resolves spontaneously. Symptomatic treatment consists of NSAIDs, e.g. indometacin.
History and etymology
Paediatric radiologist John Caffey (1895-1978) 7 first described infantile cortical hyperostosis with colleague WA Silverman in 1945.
Differential diagnosis
osteomyelitis: there are reports of association with Caffey disease
non-accidental injury
trauma
physiologic periostitis: isolated to the tibiae, femora, and humeri
skeletal dysplasias with osteosclerosis
hypervitaminosis A
hypovitaminosis C (scurvy)
hyperphosphataemia
prostaglandin E1 and E2 therapy (for intentionally maintaining ductus arteriosus patency)
infection (e.g. syphilis, tuberculosis)
Ewing sarcoma
metastatic neuroblastoma
achondroplasia
- fibroblast growth factor receptor
- rhizomelic dwarfism
- narrowing of interpedicular distance
- tombstone pelvis
- advanced paternal age is risk factor
- trident hands (long 3rd and 4th fingers)
- Numerous abnormalities are noted, including:
- stenosis of the foramen magnum with a large skull
- metaphyseal flaring giving a trumpet bone type appearance
- the femora and humeri are particularly shortened (rhizomelic shortening)
- the acetabular roof is horizontal, the iliac wings have a tombstone appearance
- horizontal sacrum
- progressive decrease in interpedicular distance in lumbar spine
- trident hands
thanatophoric dwarfism
- - most common lethal dwarfism -
- rhizomelic shortening
- telephone receiver femurs
- short ribs and long thorax
- small iliac bones
- flat vertebral bones (platyspondyly)
- - cloverleaf shaped skull
Thanatophoric dysplasia is a lethal skeletal dysplasia. It is the most common lethal skeletal dysplasia followed by osteogenesis imperfecta type II.
Epidemiology
The estimated incidence is around 1:25,000-50,000 3.
Pathology
Genetics
It results from a mutation coding for the fibroblast growth receptor 3 (FGFR3) located on chromosome 4p16.3. The type of receptor mutation is different from the FGFR mutation in achondroplasia. Inheritance is thought to be sporadic.
Subtypes
There are two recognised subtypes:
type I: marked underdevelopment of skeleton, telephone handle femurs more pronounced
type II
the presence of a cloverleaf skull may be a distinctive feature
limb shortening milder and bowing is not a feature 3
Associations
polyhydramnios 4
Radiographic features
Antenatal ultrasound
It may be difficult to accurately diagnose before the 3rd trimester (≈22 weeks) 4. Before that time it can be included in the differential if there is a short femur length measurement.
-
Sonographically-detectable features may include:
- relatively narrow thoracic cavity 4
- short, thick, bowed tubular bones, especially lower extremity 4
- thickened soft tissues of extremities 4
- comparatively large head with frontal bossing
- a cloverleaf skull appearance may also be seen: type II (see case 3)
-
Plain radiograph
-
Plain films are usually done postmortem, if done at all. Features include:
- Limbs
- proximal portions of the long limbs are small, giving a rhizomelic appearance
- long bones (typically humeri and femora) have a typical “telephone handle” bowing with metaphyseal flaring
-
Iliac bones
- usually hypoplastic
- small squared iliac wings
- may show trident acetabula
-
Plain films are usually done postmortem, if done at all. Features include:
-
Chest
- narrow chest
- short horizontal ribs
- small scapulae
-
Skull and face
- relative macrocephaly
- frontal bossing
- proptosis
- nasal bridge flattening
- kleeblattschaedel (cloverleaf) skull (with type II) 2-4
-
Spine
- platyspondyly: flattening of vertebral bodies
- normal trunk length
Treatment and prognosis
The condition is uniformly fatal within a few hours of birth either from respiratory failure or from brainstem compression from a narrow foramen magnum.
History and etymology
The term thanatophoric derives from the Greek words “thanatos” (θάνατος) meaning “death” 2 and “phoros” meaning “bearing/carrying/bringing”.
