Pathology and Radiology: Developmental Pathology Flashcards
Define malformation
Define dysplasia
Malformation: when an ORGAN fails to form properly
Dysplasia: when a TISSUE fails to form properly
At what days does neurulation typically occur?
Days 17-30
Open defects caused by failure of dysjunction of neural and cutaneous ectoderm is caused by a neural tube defect in what stage?
What are examples of this pathology?
Neurulation defects
Myelomeningocele, spina bifida, myelocele, anencephaly
Closed, skin-covered deficits are usually due to a neural tube problem happening at what point in neural tube development?
What are examples?
Post-neurulation (26-60 days)
Spina bifida occulta, holoprosencephaly, encephaloceles, hydrocephalus, lipoma, meningocele, Chiari malformation
What is the most common congenital malformation?
What is their ultimate prognosis?
Ancencephaly (absence of scalp and skull)
Either still born or die within 2 months
Patients with anencephaly have increases in what proteins in their amniotic fluid?
AFP and acetylcholinesterase
What is exencephaly?
Cerebral hemispheres are present but abnormal with associated defects to calvarium and skull base
What are risk factors for myelomeningocele?
Reduced vitamin A or folate intake, depakote or carbamazepine use, parental consanguinity
Nearly 100% of patients with myelomeningocele will also have what developmental abnormality?
Chiari II malformation
L5 bifid spinous process is associated with what developmental abnormality?
Spina bifida occulta
Where do occipital cephaloceles often develop?
What gender is most likely involved?
Between the foramen magnum and lamboid suture
More often involves females
Where do parietal cephaloceles often develop?
What gender is more often involved?
Between the lambda and bregma
More often in males
What is the most frequent type of cephalocele in southeast asian and australian aborigines?
Sincipital/Frontoethmoidal cephalocele
Absence or erosion of the crista galli may lead to what type of cephalocele?
Nasal/Sphenoethmoidal cephalocele
What type of cephalocele is associated with dermoid, epidermoid, and nasal gliomas?
Nasal/Sphenoethmoidal cephaloecele
What type of neural tube defects are caused by faulty segmental disjunction leading to formation of epithelium-lined tracts?
Dermal sinus tracts
What are the most frequent sites for dermal sinus tracts?
50% may end in what type of pathology?
Lumbar, followed by occipital
Dermoids and epidermoids
What are the hallmarks of Meckel-Gruber Syndrome?
What maternal event during days 20-26 of gestation is it associated with?
Dysplastic and cystic kidneys, cardiac anomalies, orofacial clefting, and cephaloceles
Associated with maternal hypothermia
Cleavage disorders are due to defects in what germ layer?
Prechordal mesoderm
What are the three types of holoprosencephaly and describe their characteristics.
Alobar: No midline structures (i.e. falx, corpus callosum, septum pellucidum), monoventricle, failed division of forebrain, fused basal ganglia and thalamus, severe craniofacial abnormalities such as cyclopia
Semilobar: Partial division with presence of partial falx and interhemispheric fissure with partial separation of basal ganglia and thalamus, variable craniofacial abnormalities are present
Lobar: No corpus callosum but additional midline structures present with squared frontal horns of ventricles and no craniofacial abnormalities
What is arrhinencephaly?
Absence of olfactory bulbs and cortex with replacement of corpus callosum by grey matter
Associated with holoprosencephaly and Kallman syndrome (anosmia, hypogonadism, mental retardation)
Describe the features of septo-optic dysplasia (aka de Morsier syndrome)
Absent septum pellucidum, schizencephaly, and hypoplastic optic nerves. Occurs in lobar holoprosencephaly.
Associated with seizures, hypotelorism, visual symptoms, and precocious puberty
Delayed closure of fontanelles, retention of mandibular teeth, wormian bones, and midline defects are all seen in what?
Cleidocranial dysostosis
During what gestational months do normal neuronal migration occur?
2nd to 5th months
Define heterotopias
Normal neurons in abnormal CNS locations (i.e. centrum semiovale, cerebellar white matter)
Typically do not enhance
Define ectopias
Neurons in locations they should not be in (i.e. subarachnoid space)
Define lissencephaly
Smooth brain. Variable degree of absent sulci
Define pachygyria
Overall fewer gyri and those present are enlarged
Define polymicrogyria
Multiple small gyri
Define schizencephaly
Grey matter lined cleft extending from pia to ventricles
Define porencephaly
A cleft filled with white matter occurring in brain after an insult to an otherwise normal brain
What is unilateral megalencephaly
Hamartomatous overgrowth of one hemisphere and ventricle associated with seizures
In what order of segments of the corpus callosum does it form?
Genu, Body, Splenium, Rostrum
*Forms anterior to posterior but splenium last
What segments of the corpus callosum are almost always involved in agenesis of the corpus callosum due to the order in which the segments form?
Splenium and rostrum
What are other characteristic findings on imaging of the brain in patients with agenesis of the corpus callosum?
High riding third ventricle
Probst bundles (longitudinal WM tracts indenting the lateral ventricles)
Colpocephaly
What are components of Aicardi syndrome?
Female predominance
Agenesis of CC, ocular abnormalities, and infantile spasms
What are some of the more common causes of congenital hydrocephalus?
Aqueductal Stenosis Dandy-Walker Syndrome Chiari II malformation Infection Intraventricular hemorrhage
In its simplest definition, what is a Chiari I malformation?
Tonsils extending below the foramen magnum
At each of the following age groups, what length extension below the foramen magnum defines a Chiari I malformation?
< 10 yo
< 30 yo
< 80 yo
< 90 yo
< 10 yo: 6mm
< 30 yo: 5mm
< 80 yo: 4mm
< 90 yo: 3 mm
What are some examples of causes of acquired Chiari I?
Frequent lumbar punctures or placement lumboperitoneal shunt
What are some presenting features of Chiari I malformation in adults?
Occipital headaches, L’hermitte sign, long tract signs, syringomyelia, and hydrocephalus
How does Chiari I present in infants?
Children?
Adolescents?
Infants: hydrocephalus with brainstem compression, apnea, decreased gag reflex nystagmus, spasticity
Children: spastic paralysis, bulbar dysfunction
Adolescents: progressive spasticity and cape like pain and temperature loss in upper limbs
Describe the process to occur causing a Chiari II malformation
Neural folds don’t completely meet and abnormal CSF flow leads to a small posterior fossa. This leads to cerebellum causing an upward herniation as it grows which in turn causes brainstem and vermis to push through foramen magnum
What skull and dural abnormalities are seen in patients with Chiari II malformations?
Lacunar (‘scooped out’) appearance to skull, small posterior fossa, low-lying torcula and transverse sinus, large foramen magnum, concave petrous temporal bones, short concave clivus, thin falx cerebri
How are the different portions of the hindbrain affected in a Chiari II malformation?
Upward cerebellar herniation
Downward brainstem and vermian herniation through foramen magnum
Medullary kinking
Tectal beaking
How are the various CSF spaces affected in Chiari II malformation?
Tubular 4th ventricle
Large 3rd ventricle with massa intermedia
Colpocephaly (large atrial and occipital horns)
Aqueductal stenosis
Hydrocephalus
Small cisterna magna
Describe a Dandy-Walker malformation
Presence of 4th ventricular cyst which may or may not communicate with fourth ventricle. Partial or complete absence of vermis. Often from failure of formation of superior medullary velum
How can one distinguish the presence of a mega cisterna magna from a posterior fossa arachnoid cyst?
Mega cisterna magna will contain intrathecal contrast when injected, posterior fossa arachnoid cysts will not
What is Lhermitte-Duclos disease?
Hypertrophied cerebellar granular later and increased myelin in molecular layer of cerebellum with thick folia. Considered a hamartoma. Associated with Cowden syndrome
What’s the difference between hydromyelia and syringomyelia?
Hydromyelia: dilation of central cord of spinal canal and lined with ependyocytes
Syringomyelia: fluid filled cavity in the spinal cord lined with astrocytes
What time frame after birth is surgical repair of craniosynostosis usually performed?
3-6 months of age
In what direction does the head increase in size in scaphocephaly? Premature fusion of what suture is the cause?
A-P direction
Due to premature fusion of sagittal suture
skaphe - light boat in Greek
Anterior plagiocephaly is caused by what synostosis?
Unilateral coronal synostosis. A-P diameter is decreased on one side with increased width on coronal dimension
What causes brachycephaly?
What syndromes is it associated with?
Bilateral coronal synostosis
Apert and Crouzon syndromes
Posterior plagiocephaly is caused by what synostosis? What other condition is similar but must be differentiated?
How can the above differentiation occur?
Unilateral lamboid synostosis
Positional plagiocephaly will have similar findings
Synostosis is present from birth, positional is acquired after sleepin on that side frequently. Treatment for positional plagiocephaly is changing sleeping position, not surgery. Tilting of the skull base and ipsilateral ear displacement posteriorly and inferiorly with a prominent mastoid process will support a diagnosis of unilateral lamboid synostosis
What does metopic synostosis cause?
Trigoncephaly. Failure of fusion of metopic suture which is anterior component of sagittal suture
Turricephaly causes a tall and broad head due to premature fusion of what sutures?
Bilateral coronal and sphenofrontal sutures
Oxycephaly is a cone shaped head from premature fusion of what sutures?
Multiple. Usually bilateral coronal and other sutures such as lamboid
What does pansynostosis cause?
Luckenschadel head from premature fusion of mutiple sutures
What are some features of Crouzon syndrome?
Autosomal dominant craniofacial syndrome:
- Midface hypoplasia, exophthalmos, agenesis of corpus callosum, congenital hydrocephalus, degree of mental retardation, synostosis, mutations of fibroblast growth factor receptor 2
What is the second most common craniofacial syndrome and what are its features and mutation?
Apert syndrome
Autosomal dominant, turricephalic, maxillary hypoplasia, orbital hypertelorism, syndactyly, deafness, flat nose, mental retardation, GI/GU/Cardiac abnormalities, increased incidence of encephaloceles,, mutations of fibroblast growth factor receptor
What syndrome is characterized by premature fusion of the upper cervical vertebra?
Klippel-Feil Syndrome
Sprengel deformity and Chiari I malformation are associated with what syndrome?
Klippel-Feil Syndrome
Sprengel syndrome is elevation of the scapula, likley due to the premature fusion of the upper cervical vertebra