Chapter 10 Infancy and Childhood Quiz

Diseases of Infancy and Childhood

• Children's diseases differ from adult diseases, often unique to childhood stages
• Perinatal period diseases are significant factors in morbidity and mortality, with survival chances increasing weekly
• US infant mortality rate declined from 20 per 1000 live births in 1970 to 5.8 in 2014
• African American infant mortality rate remains higher than that of American whites
• Worldwide, infant mortality rates vary widely, with significantly higher rates in some regions
• Leading causes of death in the first 12 months include congenital anomalies, prematurity, low birth weight, SIDS, and maternal complications
• After the first year, unintentional injuries from accidents are the leading cause of death, followed by congenital anomalies and malignant neoplasms
• Congenital anomalies are structural defects present at birth; some may not become apparent until later in life
• Approximately 1 in 33 babies born in the US have a birth defect (congenital anomaly) each year
• Congenital anomalies may not always have a clear genetic basis

Congenital Anomalies

• Malformations are primary errors in morphogenesis, inherent to the abnormal development process.
• Disruptions are a consequence of secondary damage to previously normal structures due to external influences
• Deformations result from extrinsic disturbances and external forces, impacting about 2% of newborns
• A sequence is a cascade of anomalies triggered by a single initial abnormality.
• A syndrome refers to multiple anomalies believed to be pathologically related, stemming from a single etiological factor such as a viral infection or chromosomal abnormality.
• Agenesis refers to the complete absence of an organ, while aplasia describes a lack of growth in the existing primordium.
• Atresia is characterized by the absence of an opening, commonly in hollow organs
• Hypoplasia involves incomplete development and reduction in organ size, the opposite of hyperplasia (increased size)
• Trophies are differences in cell size (either hypertrophy or hypotrophy)
• Dysplasia describes abnormal organization of cells (distinct from neoplasia)
• The primary causes of congenital anomalies include genetic factors, environmental influences, and multifactorial interactions (of genes and environment).

Fetal Hydrops

• Fetal hydrops is the accumulation of fluid within a fetus during intrauterine development, potentially due to Rh blood group incompatibility, hemolytic anemia, cardiovascular defects, chromosomal abnormalities, or fetal anemia.
• Immune hydrops is a condition stemming from blood group antigen incompatibility (primarily Rh factor) between the mother and fetus. The mother develops an immune response in subsequent pregnancies.
• In Rh incompatibility, free antibodies traverse the placenta and affect the fetus's red blood cells.
• Non-immune hydrops has several causes, including cardiovascular defects or chromosomal abnormalities, and is contrasted with immune hydrops.
• Fetal anemia resulting from several factors, can also cause hydrops.

Perinatal Infections

• Fetal and perinatal infections are acquired via transcervical (ascending) or transplacental (hematogenous) routes.
• Transcervical infections often occur due to bacterial or viral infections reaching the fetus either through inhalation of infected amniotic fluid or the birth canal.
• Transplacental infections involve infections carried through the placenta. Microorganisms from the mother frequently infect the fetus.

Neonatal Respiratory Distress Syndrome (RDS)

• RDS, also known as hyaline membrane disease, is characterized by hyaline membrane deposition in the lungs.
• RDS is more common in premature infants and results from surfactant deficiency.
• Surfactant, primarily dipalmitoyl phosphatidylcholine (lecithin), reduces surface tension in the alveoli, making lung expansion easier.
• RDS pathogenesis involves surfactant immaturity and deficiency, leading to alveolar collapse, impaired gas exchange, hypoxemia, and CO2 retention.
• Cortisol, insulin, prolactin, thyroxine and TGF-β regulate surfactant synthesis.

Necrotizing Enterocolitis (NEC)

• NEC is a common disease, primarily occurring in premature infants.
• NEC is characterized by necrotizing lesions of the gastrointestinal tract.
• Enteral feeding is a substantial risk factor for NEC
• The pathogenesis of NEC is multifaceted yet frequently related to the introduction of bacteria to stimulate inflammation of the intestinal tract.

Sudden Infant Death Syndrome (SIDS)

• Sudden infant death syndrome (SIDS) is the unexpected death of an infant under a year old following a thorough investigation.
• Many deaths in infants have treatable causes (like infections)
• SIDS is a diagnosis of exclusion.

Tumors and Tumorlike Lesions of Infancy and Childhood

• Tumors are relatively rare in infancy & childhood, comprising only 2%.
• Benign tumors and tumor-like lesions such as hemangiomas, fibrous lesions, and teratomas are more common than malignant tumors.
• Teratomas are often found in various body sites but sacrococcygeal teratomas are most common, frequently presenting in the first 6 months
• Hemangiomas are the most common tumors in infancy. They frequently regress spontaneously.
• Neuroblastomas occur in the sympathetic ganglia and adrenal medulla, typically occurring around 18 months. Age, stage, histology, MYCN status and DNA ploidy play a crucial role in prognosis.
• Wilms tumor is the most common primary renal tumor in children. It commonly presents between ages 2 and 5.

Inborn Errors of Metabolism

• Inborn errors of metabolism are genetic disorders that affect metabolic processes, often resulting from abnormal accumulation of metabolites or deficiency of necessary products.
• PKU, galactosemia, and cystic fibrosis are some examples of common inborn errors of metabolism.
• Early diagnosis and intervention are crucial for preventing complications in many inborn errors.