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Diseases of Infancy and Childhood. Congenital Anomalies. Causes of death by age groups – Table 10-1 Definitions Causes of anomalies Pathogenesis of anomalies. Congenital Anomalies. Definitions: Malformation – intrinsically abnormal developmental process
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Congenital Anomalies • Causes of death by age groups – Table 10-1 • Definitions • Causes of anomalies • Pathogenesis of anomalies
Congenital Anomalies • Definitions: • Malformation – intrinsically abnormal developmental process • Disruption – extrinsic disturbance in morphogenesis, secondary destruction of a previously normal organ or region • Deformation – abnormal biomechanical force leading to a structural abnormality • Sequence – cascade of anomalies triggered by one initiating aberrration • Syndrome – constellation of anomalies, usually a single etiologic agent that simultaneously affects several tissues
Congenital Anomalies • Causes: • Genetic • Environmental – infections, maternal disease states, drugs and other chemicals, irradiations • Multifactorial • Unknown – 40-60% • Table 10-3
Congenital Anomalies • Pathogenesis • The timing of the prenatal teratogenic insult has an important impact on the occurrence and the type of anomaly produced • The complex interplay between environmental teratogens and intrinsic genetic defects is underscored by the fact that features of dysmorphogenesis caused by environmental insults can often be recapitulated by genetic defects in the pathways targeted by these teratogens
Disorders of Prematurity • Causes of prematurity and fetal growth restriction • Neonatal respiratory distress syndrome • Necrotizing enterocolitis
Disorders of Prematurity • Appropriate for gestational age – 10th-90th percentile • Small for gestational age - <10th percentile • Large for gestational age - > 90th percentile • Pre-term – before 37 weeks • Post-term – after 42 weeks
Disorders of Prematurity • Causes of prematurity and growth restriction • Preterm premature rupture of membranes • Intrauterine infection • Uterine, cervical, and placental structural abnormalities • Multiple gestation • Fetal conditions • Placental insufficiency • Maternal conditions
Disorders of Prematurity • Hyaline membrane disease (neonatal RDS) • Necrotizing enterocolitis • Sepsis • Intraventricular hemorrhage • Patent ductusarteriosus • Long-term complications
Disorders of Prematurity • Neonatal RDS • Immaturity of the lungs is the most important substrate upon which this condition develops • The fundamental defect in RDS is the deficiency of pulmonary surfactant • Role of glucocorticoids is particularly important • Figure 10-7- Pathophysiology of RDS • Retinopathy of prematurity • Bronchopulmonary dysplasia
Perinatal Infections • Transcervical ( Ascending) infections – most bacterial and a few viral ( herpes simplex) • Transplacental (Hematologic) infections – most parasitic and viral and a few bacterial, TORCH • Sepsis – Group B streptococcus
Fetal Hydrops • Immune hydrops – • Blood group incompatibility between mother and fetus • Anemia and jaundice • Pathogenesis – Figure 10-11 • Nonimmunehydrops • Cardiovascular defects • Chromosomal anomalies • Fetal anemia
Inborn Errors of Metabolism • PKU • Galactosemia • Cystic Fibrosis
Phenylketonuria (PKU) • Biochemical abnormality: • Inability to convert phenylalanine into tyrosine • Hepatic PAH system • BH4, DHPR • Important to recognize PKU variants • Severe mental retardation, seizures, decreased pigmentation of hair and skin, eczema • Maternal PKU
Galactosemia • Two variants • More common – lack of GALT ( galactose-1-phospahte uridyltransferase) • Rare – deficiency of galactokinase • FTT, vomiting and diarrhea, jaundice, hepatomegaly, E. coli sepsis, cataracts, mental retardation
Cystic Fibrosis • Also called mucoviscidosis • Disorder of ion transport in epithelial cells that affects fluid secretion in exocrine glands and the epithelial lining of the respiratory, GI, and reproductive tracts • Primary defect – Abnormal function of an epithelial chloride channel protein encoded by the CFTR gene • Functions of CFTR • Regulates multiple ion channels and cellular processes • Functions are tissue-specific: sweat glands vsresp and GI tracts • Mediates transport of bicarbonate ions
Cystic Fibrosis • CFTR gene mutations • Class I: defective protein synthesis • Class II : abnormal protein folding, processing, and trafficking • Class III: defective regulation • Class IV: decreased conductance • Class V: reduced abundance • Class VI: altered regulation of separate ion channels
Cystic Fibrosis • NB screening – controversial • Clinical features and diagnostic criteria – Table 10-6
SIDS • The sudden death if an infant under one year of age which remains unexplained after a thorough case investigation, including performance of a complete autopsy, examination of the death scene, and review of the clinical history. • Risk factors and postmortem findings- Table 10-7 • ALTE – apparent life-threatening event • Back to Sleep campaign • “Triple-risk” model • Vulnerable infant, critical developmental period of homeostatic control, exogenous stressor
Tumors and Tumor-Like Lesions of Infancy and Childhood • Benign and tumor-like lesions • Malignant tumors • Incidence and types • Neuroblastic Tumors • Wilms Tumors
Benign Tumors and Tumor-like Lesions • Hemangioma • Lymphatic tumors • Fibrous tumors • Teratomas
Malignant Tumors • Incidence and types – Table 10-8 • -blastomas • Small round cell tumors
Neuroblastic Tumors • Spontaneous or therapy-induced differentiation of primitive neuroblasts into mature elements, spontaneous tumor regression, wide range of clinical behaviour and prognosis • ALK gene • Homer-Wright pseudorosettes, ganglioneuroma, Schwann cells • Staging • Prognostic factors – Table 10-9 • Clinical features • Abdominal masses, fevers, weight loss • “blueberry muffin” • Proptosis and periorbitalechymosis • Catecholamine production • Bone pain, respiratory complaints, GI complaints
Wilms Tumor • Biology of tumor illustrates important aspects of childhood tumors • Relationship between malformations and neoplasia • Organogenesis and oncogenesis • Two-hit theory of recessive tumor suppressive genes • Role of premalignant lesions • Potential for judicious treatment modalities to dramatically affect prognosis and outcome
Wilms Tumor • Nephrogenic rests • Large abdominal mass, hematuria, abdominal pain, intestinal obstruction, hypertension • Syndromic tumor • WAGR syndrome – aniridia, genital abnormalities, mental retardation • Denys-Drash syndrome – gonadal dysgenesis, nephropathy • Beckwith-Wiedermann syndrome – enlargement of body organs, genomic imprinting • WT1 and WT2 • Beta-catenin