Chapter 10--Diseases of Infancy and Childhood Flashcards
A morphologic defect present at birth
Congenital anomaly
What % of fertilization are so anomalous that they never develop into a viable conceptus?
20%
Complete absence of an organ and its associated primordium
Agenesis
Absence of an organ due to failure of the developmental anlage
Aplasia
Absence of an opening usually of a hollow visceral organ
Atresia
In the context of malformation, refers to abnormal cellular organization
Dysplasia
Enlargement of an organ associated with increased number in cells
Hyperplasia
Underdevelopment of an organ with decreased number of cells
Hypoplasia
Decreased organ size due to decreased cell size
Hypotrophy
Intrinsic disturbances in morphogenesis; typically multifactorial and not caused by single genetic defect
Malformation
Extrinsic disturbances in morphogenesis causing a secondary destruction of a previously developmentally normal tissue; NOT heritable!
Disruptions
Example of disruption
Amniotic band resulting from an amniotic rupture that causes fibrous stranding that encircles, compresses or attaches to a developing body part
Result from an external disturbance in morphogenesis. Caused by localized or generalized compression by abnomal mechanical forces and they manifest as abnormalities in shape, form or position (club feet)
Deformations
Most common underlying factor in deformations
Uterine constraint; first pregnancy, small uterus, leiomyomas
Constellation of anomalies resulting from one initiating aberration that leads to multiple secondary effects
Sequence
Classical example of a sequence
Potter sequence
What happens in potter sequence?
Oligohydramnios–decreased amniotic fluid–causes fetal compression with facial flattening, hand and foot malpositioning, hip dislocation, and chest compression with Hypoplasia
Combination of anomalies that cannot be explained on the basis of one initiating aberration and a subsequent cascade.
Syndrome
Most syndromes are caused by a single pathology that simultaneously affects several tissues (viral infection or chromosomal abnormality)
3 causes of developmental anomalies
Genetic causes
Environmental causes
Multifactorial causes
2 genetic causes of developmental anomalies
Chromosomal abnormalities
Single gene mutations
5 examples of chromosomal abnormalities that cause developmental anomalies?
Trisomy 21 (Down Syndrome) Klinefelter Syndrome (47 XXY) Turner Syndrome (XO) Trisomy 13 (Patau syndrome) Trisomy 18 (Edwards syndrome)
How do single gene mutations cause developmental anomalies?
Loss of function genes that drive organogenesis or development; hedgehog genes
5 examples of environmental causes of developmental anomalies
Viruses Drugs and chemicals Alcohol Radiation Maternal diabetes
Most common fetal viral infection? What does it result in?
Cytomegalovirus–mental retardation, microcephalic, deafness
What trimester is the highest risk period for cytomegalovirus infection?
Second trimester
What is congenital rubella syndrome?
A rubella infection (German measles/3 day measles) occurring before 16 weeks of gestation that can result in tetras of defects: cataracts heart defects deafness mental retardation
An agent or factor that causes a malformation in an embryo?
Teratogen
Examples of drugs and chemicals that act as environmental causes of developmental anomalies (5 examples)
Thalidomide Folate antagonists Androgenic hormones Anticonvulsants 13-CIS-retinoic acid
Most widely used Teratogen?
Alcohol
Structural anomalies, cognitive and behavioral deficits related to alcohol use in mother
Fetal alcohol spectrum disorders
Classic teratogenic phenotype that describes infants most severe affected by fetal alcohol spectrum disorders
Fetal alcohol syndrome
Teratogenic phenotype of fetal alcohol syndrome
Growth retardation Microcephaly Atrial septal defects Short palpebral fissures (elliptic space bw medial and lateral can't hi of the two open eye lids) Maxillary Hypoplasia
Large fetus caused by maternal diabetes is called?
Fetal macrosomia
Series of malformations occurring with maternal diabetes; hyperinsulinemia resulting in increased body fat, muscle mass and organometallic, cardiac anomalies neural tube defects and other CNS malformations
Fetal macrosomia
Interaction of environmental factors with mutated genes; independently they may have no or minimal effect
Multifactorial causes of developmental anomalies
Two examples of multifactorial causes of developmental anomalies
Congenital hip dislocation–shallow Acetabular socket (genetics) and a breech delivery (environment)
Neural tube defects–genetic predisposition (genetic) and low maternal folate (environmental)
Importance of timing and teratogenic insult
Timing of any teratogenic insult influences the nature and incidence of the anomaly produced–a given agent can have a significantly different outcome depending on when it is encountered
Embryonic period of development
First 8 weeks after fertilization
Teratogenic influence of the early (first 3 weeks) of the embryonic period
Either kills, so many cells die causing spontaneous abortion or limited numbers of cells are affected such that the fetus can recover without consequence
Fetal period of development
Weeks 9-36
Sensitivity to teratogens during the fetal period
Greatly reduced to teratogenic agents; the fetus is still susceptible to growth retardation
Do teratogens and genetic defects typically act on the same developmental pathways?
They can/do and will result in similar anomalies. Example: valproate embropathy–valproic acid (an anti-seizure medication) is teratogenic and disrupts the homeobox transcription factors. Homeobox gene mutations give rise to the same congenital anomalies
Most common cause of neonatal mortality
Congenital anomalies
Second most common cause of neonatal mortality
Prematurity
When does the greatest mortality of childhood occur?
In the first year and then declines progressively
When is a baby considered preterm?
Birth before 37
Birth before 42 weeks
POST-term
What are appropriate age and weight for gestation?
Between 10th and 90th percentile; below 10=small and above 90 is large
What are the major risk factors for prematurity? (4)
Preterm premature rupture of the placental membranes (PPROM)
Intrauterine infection
Uterine, cervical and placental structural abnormalities
Multiple gestational
What is PPROM?
Preterm premature rupture of the placental membrane
What is the most common cause of prematurity?
Preterm premature rupture of the placental membranes
What is the pathophysiology of PPROM?
Placental inflammation and matrix metalloproteinase activation
What is choroioamnionitis?
Inflammation of the placental membrane
What is funisitis?
Inflammation of the umbilical cord
Organisms associated with intrauterine infection and prematurity
Urea plasma urealyticum Mycoplasma hominids Gardnerella vaginalis Trichomonas Gonorrhoea Chlamydia
What are the 3 categories of causes for fetal growth restriction/intrauterine growth retardation?
Fetal
Placental
Maternal
Fetal causes of fetal growth restriction/intrauterine growth retardation
Despite adequate maternal nutritional supply, there is compromised fetal growth potential; typically there is symmetric growth restriction–all organ systems are proportionally affected
What are 3 fetal causes of fetal growth restriction/intrauterine growth retardation?
Chromosomal abnormalities (trisomies) Congenital anomalies Congenital infections (TORCH)
What does TORCH stand for?
Toxoplasmosis Other Rubella Cytomegalovirus Herpes virus
Placental causes of fetal growth restriction/intrauterine growth retardation
Vigorous fetal growth in the 3rd trimester demands adequate placental growth and development; defects in placental supply typically cause asymmetric growth retardation, with relative sparing of the brain
What are 7 placental causes of fetal growth restriction/intrauterine growth retardation?
- Umbilical-placental vascular anomalies
- Placental abrupt ion-placenta separates from uterus
- Placenta Previn (low lying placenta)
- Placental thrombosis and infarction
- Placental infections
- Multiple gestations
- Placental mosaicism
What is placental mosaicism?
Genetic mutations arising after zygote formation lead to two genetic populations of cells within the placenta and/or fetus
What kind of fetal growth restriction/intrauterine growth retardation causes is the most common?
Maternal
What do maternal causes of fetal growth restriction/intrauterine growth retardation result in?
Decreased placental blood supply
What are the 7 maternal causes of fetal growth restriction/intrauterine growth retardation?
Preeclampsia--high blood pressure and protein in urine Hypertension Inherited thrombophilias Malnutrition Narcotic or alcohol Intake Cigarette smoking Certain drugs (teratogens)
5 risks associated with prematurity? What complications are associated with prematurity?
Hyaline membrane disease (neonatal respiratory distress syndrome) Necrotizing enterocolitis Sepsis Intravenricular hemorrhage Long term complications
Causes of neonatal respiratory distress?
Respiratory distress syndrome Maternal sedation Blood or fluid aspiration Fetal head injury Umbilical cord around neck
Most common cause of neonatal respiratory distress?
Respiratory distress syndrome (also known as hyaline membrane disease)
Incidence of neonatal RDS is 60% in infants born before 28 weeks of gestation and less than 5% of infants born after how many weeks gestation?
37 weeks
Key feature of respiratory distress syndrome
Inadequate pulmonary surfactant
Cell type that makes surfactant
Type II pneumocytes
Surfactant production by type II pneumocytes is highest at what week of gestation?
30? 35??
What is surfactant made of?
Phospholipids and glycoproteins
Decreased surfactant results in ___ alveolar surface tension, progressive alveolar _____ and increasing inspiratory pressures required to expand the ____
Increased
Atelectasis
Lung alveoli
RDS is associated with what damaging effects?
Acidosis Pulmonary vasoconstriction Pulmonary hypoperfusion Capillary endothelial and Alvolar epithelial damage Plasma leakage into alveoli
In neonatal RDS plasma proteins leak into the alveoli and combine with fibrin and necrotic Alvolar pneumocytes to form ____ that further impede gas exchange
Hyaline membrane
How do corticosteroids reduce neonatal respiratory distress syndrome?
Induce surfactant lipid and apoprotein production
Grossly what is seen in lungs of a neonatal RDS patient?
Lungs are solid, airless and reddish purple
What can you see microscopically in patients with neonatal RDS?
Alveoli poorly developed and frequently collapsed; protein acess membranes line respiratory bronchioles, alveolar ducts and random alveoli
Lung maturity in neonatal respiratory distress syndrome directly reflects the synthesis of what?
Surfactant synthesis
What aspect of the amniotic fluid is measurable and reflects lung maturity in neonatal respiratory distress syndrome (surfactant synthesis?)
Lecithin/sphingomyelin ratio
Necrotizing enterocolitis occurs most commonly in?
Premature infants; it is inversely proportional to gestational age
What predisposing conditions can lead to necrotizing enterocolitis?
Bacterial colonization
Enteral feeding
Etiology and perinatal mortality rate of NEC
Induction of inflammatory mediators in bowel (platelet activating factor production) promotes enerocyte apoptosis and increased intercellular permeability. This augments trans mural bacterial migration with a viscous cycle of inflammation and mucosal necrosis. Perinatal mortality is high
NEC typically involves what areas of the bowel?
Terminal ileum, cecum, and right colon
Microscopically what is seen in NEC
Mucosal to trans mural coagulative necrosis, ulceration, bacterial colonization and submucosal gas bubbles
How are perinatal infections usually acquired?
Transcervically or transplacentally
Transcervical route of perinatal infection
Ascending infection up and through the cervix
Transplacentally route of perinatal infection
Transferred to fetus from mother through placenta; hematologic
Most bacterial and a few viral perinatal infections occur via the ____ route
Cervicovaginal; transcervical (ascending route)
How does the fetus usually become infected in a transcervical (ascending) infection?
Inhaling infected amniotic fluid into lungs during parturition, it passes through an infected birth canal
If there is a transcervical (ascending) infection, what diseases will also be present? What often is the result of a transcervical ascending infection
Choroioamnitis and funisitis
Preterm birth
Most common sequelae of a transcervical (ascending) infection
Preterm birth
What are the most common sequelae of a transcervical (ascending) infection
Pneumonia, sepsis, and meningitis
How do most transplacental (hematologic) infections enter the fetal bloodstream?
Via the chorionic villi
Sequelae of transplacental (hematologic) infection are commonly the same regardless of when it occurs. T/F?
False–depends highly on the timing and the organism
Do all TORCH infections have similar manifestations?
Yes
Manifestations of TORCH infections
Fever Encephalitis Chorioetnitis Hepatosplenomegaly Pneumonitis Myocarditis Hemolytic anemia Skin lesions (vesicular hemorrhagic)
Long term sequela of TORCH infection
Growth retardation Mental retardation Cataracts Congenital cardiac anomalies Bone defects
Early-onset (during the first 7 days of life) sepsis is most commonly due to _______, acquired at or shortly before birth
Group B streptococcus
Late-onset (up to 3 months) sepsis is often due to _____ or _____
Listeria, candida
What is fetal hydrops?
Fetal edema fluid collection during intrauterine growth
Severe and generalized fluid collection in fetus is referred to as what?
Hydrops fetalis
Postnuchal fluid accumulation in fetus
Cystic hyngroma
Hemolytic disorder caused by blood group incompatibility between mother and fetus
Immune hydrops
Underlying basis of disease in immune hydrops
Immunizations of the mother by antigens present on fetal erythrocytes, followed by free passage of maternal antibodies across the placenta and into fetus; these abs bind to erythrocytes and mediate complement dependent lysis and/or phagocytosis by Fc receptor bearing cells; results in fetal red cell hemolysis
What are the most important molecules on erythrocytes that are associated with immune hydrops?
RhD and ABO blood group antigens
What is the major sequela of immune hydrops?
Anemia
In immune hydrops, _____ develops because hemolysis of RBCs and produces unconjugated bilirubin; this passes across the poorly developed fetal blood-brain barrier and causes CNS injury (_____)
Jaundice, kernicterus
Major causes of non-immune hydrops
Cardiovascular defects Chromosomal anomalies (Turner syndrome, trisomies 18 & 21) Fetal anemia unrelated to immune hemolysis
In fetal anemia, what two things are pale?
Fetus and placenta
What is erythroblastosis fetalis?
Bone marrow exhibits compensatory erythroid hyperplasia and (could be in the setting–immune hydrops fetalis/anemia) multiple organs exhibit extra medullary hematopoiesis; increased hematopoiesis deposits large numbers of immature RBCs in peripheral. Blood (erythroblastosis fetalis)
3 inborn errors of metabolism and genetic disorders
PKU
Galacotemia
Cystic fibrosis
Role of phenylalanine hydroxylase (PAH) in phenylketonuria
PAH is an enzyme that irreversibly converts phenylalanine to tyrosine; in this autosomal recessive disease, most commonly there is a bi allelic mutation of the gene encoding PAH resulting in the accumulation of phenylalanine and brain damage
What is the enzyme that undergoes biallelic mutations in phenylketonuria?
Phenylalanine hydroxylase
Intestinal mucosal lactase converts lactose into glucose and ____
Galactose
One Name the disorder: one of the enzymes that metabolizes galactose undergoes a genetic mutation and results in the accumulation of varying toxic metabolites of galactose
Galactosemia
In the most common and clinically significant form of Galactosemia there is an autosomal recessive mutation in what enzyme?
Galactose-1-phosphate accumulated levels of galatitol and galactonate
Most common lethal genetic disease affecting Caucasian populations in the US
Cystic fibrosis
Autosomal recessive disorder that affects epithelial cell ion transport and causes abnormal fluid secretion in exocrine glands, respiratory GI and reproductive mucosa
Cystic fibrosis
Gene mutated in cystic fibrosis encodes what protein?
Cystic fibrosis transmembrane conductance regulator (CFTR) protein
CFTR protein in cystic fibrosis only effects the sodium channel. T/F
False it regulates many ion channels and cellular process
What epithelial sodium channel is most greatly effected in CF by the CFTR protein?
ENaC channel
Role of the ENaC
ENaC is an apical membrane protein in exocrine epithelium that is responsible for sodium transport
Describe the role of CFTR in eccrine glands, and the disease state in CF
In eccrine sweat duct epithelium, normal CFTR augments ENAc activity. In CF, augmented activity is lost, resulting in hypertonic sweat
Role of CFTR in respiratory and intestinal epithelium and in the disease state of CF
Normal CFTR inhibits ENaC activity. In CF, augmented (increased) ENaC activity increases sodium movement into cells; coupled with reduced luminal chloride, there is increased osmotic water resorption from the lumen, leading to dehydration of mucus secretions. Defective mucociliary action and the accumulation of hyper concentrated viscous secretions ultimately obstruct ductascending outflow from the organs=mucoviscidosis
CFTR mediates bicarbonate transport; CFTR is co-expressed with a family of anion exchangers called what?
SLC26
In the setting of some CFTR mutations associated with bicarbonate transport, ___ fluids are secreted leading to an ___ environment that causes mucin precipitation and duct obstruction
Acidic
What is the most common CFTR gene mutation (70% worldwide)?
A three nucleotide deletion for phenylalanine at position 508 (F508)
How does CF affect the pancreas?
Mucus accumulation in small ducts with mild dilation to total atrophy of exocrine pancreas; impairment of fat absorption and avitaminosis A and duct all squamous metaplasia
How does CF affect the intestines?
Thick viscous plugs of mucus (meconium ileum) can cause small bowel obstruction
Thick viscous plugs of mucous can cause small bowel obstruction in CF. What are these called?
Meconium ileus
How can CF affect the liver and what it results in
Bile canalicular plugging by mucinous material that results in diffuse hepatic cirrhosis
How CF affects salivary glands
Similar to pancreas–progressive dilation of ducts, duct all squamous metaplasia and glandular atrophy
Which organ results in the most serious complications in CF? How?
Lungs–mucus cell hyperplasia and viscous secretions block and dilate bronchioles. Superimposed infections and pulmonary abscesses are common
Which microbes are most commonly associated with lung infections in CF?
Staphylococcus aureus
Haemophilus influenzae
Pseudomonas aeruginosa
Which microbe is associated with fulminant (coming on suddenly with great severity including death) onset in CF?
Burkholderia cepacia
How does CF affect the male genital tract?
Azoospermia and infertility occur in 95% of male patients surviving into adulthood, frequently with congenital absence of the vas deferens
What are the most common causes of death in CF?
Cardiorespiratory complications: chronic cough, persistent lung infections, obstructive pulmonary disease, cor pulmunale
Definition of SIDS
Sudden death of infant less than 1 yr of age that remains unexplained after a thorough case investigation, including performance of a complete autopsy, examination of death scene, and a review of clinical history
SIDS is a diagnosis of ____ and a disease of unknown cause
Exclusion
When and in what position do infants usually die in SIDS?
Infants usually die while asleep, mostly in the prone or side position. Most SIDS deaths occur bw 2 and 4 months of life; 90% occur within 6 months of birth
Leading cause of death in children between 1 month and 1 year of age and the 3rd leading cause of infant death overall
SIDS
Hypothesis of SIDS
Developmental immaturity of critical brain stem regions (arcuate nucleus) involved in arousal and cardio respiratory control and that environmental influences (infection) further fatally impair these regulatory mechanisms
Parental risk factors for SIDS
Young maternal age Short gestational interval Inadequate prenatal care Low socioeconomic status Maternal smoking or drug abuse
Infant risk factors in SIDS?
Low birth weight
SIDS in a prior sibling (suggests a genetic component)
Male gender
What are some environmental risk factors in SIDS?
Sleeping prone
Hyperthermia
Sleeping on soft surface
Leading cause of death (after accidents) in US children bw ages 4 and 14
Cancers
What % of all cancers occur in infancy and childhood?
2%
What is more common in infancy and childhood? Benign or malignant tumors?
Benign
Another name for heterotopia/choristoma?
Microscopically normal cells or tissue present in abnormal locations; are usually of little clinical significance but can be the origin of true neoplasms
Example of heterotopia/choristoma
pancreatic tissue in the wall of the stomach
Excessive but focal overgrowth of mature cells or tissue native to organ or site in which they occur that do not recapitulate normal architecture. Are histologically benign but can be clinically signficant
Hemartomas
4 benign tumors and tumors like lesions of infancy and childhood
Hemangiomas
Lymphatic tumors
Fibrous tumors
Teratomas
Most common tumors of infancy
Hemangiomas
Where do Hemangiomas occur?
Face and scalp
Hemangioma may represent one facet of hereditary disorders such as _____
Von Hippel-Lindau disease
_____ are composed of cystic and cavernous lymphatic spaces, with variable numbers of associated lymphocytes
Lymphatic tumors
____ range from sparsely cellular proliferation a to richly cellular lesions indistinguishable from adult fibrosarcomas
Fibrous tumors
Congenital infantile fibrosarcomas has an ____ prognosis
Excellent
When are two peaks for Teratoma incidence?
At age 2 and in late adolescence
40% of teratomas occurring in infancy and childhood occur where?
Sacrococcygeal region
What % of teratomas are benign and mature?
75%
What is the most frequent childhood cancer of the hematopoietic system?
Acute lymphoblastic leukemia (ALL)
Most frequent childhood cancers of the CNS
Astrocytoma
Medulloblastoma
Ependymoma
Most frequent childhood cancer of the adrenal medulla
Neuroblastoma
Most frequent childhood cancer of the retina
Retinoblastoma
Most frequent childhood cancer of soft tissue
Rhabdomyosarcoma
Most frequent childhood cancers of the bone
Ewing sarcoma
Osteogenic sarcoma
Most frequent childhood cancer of the kidney
Wilms tumor
What accounts for more deaths in children younger than 15 years than all other tumors?
Leukemia
Many pediatric cancers tend to have a more primitive ____ rather than a frankly anaplastic histology, with features of organogenesis consistent with the site of origin
Embryonal
Tumors with a more primitive embryo all rather than a frankly anaplastic histology with features of organogenesis consistent with site of origin are collectively labeled as?
Small round blue cell tumors
7 tumors that fall under the category of small round blue cell tumors
Lymphoma Wilms tumor Rhabdomyosarcoma Ewing sarcoma/ peripheral neuroectodermal tumor (PNET) Neuroblastoma Medulloblastoma Retinoblastoma
Where do Neuroblastoma tumors arise?
Adrenal medulla or sympathetic ganglia
What is the most common Neuroblastic tumor?
Neuroblastoma
1-2% of Neuroblastic tumors are familial associated with what enzyme mutations?
Anaplastic lymphoma kinase (ALK)
40% of Neuroblastoma occur where?
Adrenal medulla
Tumor characterized by sheets of small round blue Neuroblastoma within a neurofibrillay background and characteristic Homer-wright pseudo rosettes
Neuroblastoma
Wilms tumors are presumed to be related with Germaine mutations and are associated with malformation syndromes all involving what chromosome?
11p
When is Wilms tumor usually diagnosed? Is it malignant? Survival rate?
Usually diagnoses between ages 2 and 5, is malignant but has overall survival rate of more than 90%
Syndrome associated with a associated deletion on chromosome 11p band 13 and patients have aniridia (absence of Iris), genital anomolies, mental retardation and a 33% chance of developing a Wilms tumor
WAGR syndrome: Wilms tumor, Aniridia, Genital anomolies, Retardation (mental)
Syndrome in which patients have gonadal dysgenesis and nephropathy leading to renal failure; 90% develop Wilms tumors
Denys-Drash syndrome
Syndrome in which patients have enlarged body organs, hemilhypertrophy, adrenal cytomegaly, and a predisposition to developing Wilms and other primitive tumors
Beckwith-Wiedermann syndrome
Wilms tumors are soft, large, well circumscribed renal masses characterized by what triphasic features?
Blastema
Immature stroma
Tubules
(Trying to recapitulate nephrogenesis)
Identifying rests on a unilateral Wilms tumor resection mandates watchful waiting for a malignancy on the ____ side; nephrogenic rests are putative precursor lesions to Wilms tumors are are seen in renal parenchyma adjacent to 40% of unilateral lesions; the frequency rises to nearly 100% in bilateral Wilms tumors
Contralateral
Patient presentation of Wilms tumor:
Large abdominal masses; hematuria, pain, hypertension, bowel obstruction