Pediatric Pathology 1 PDF Lecture Notes

PEDIATRIC PATHOLOGY I Ana Yuil-Valdes, M.D. Department of Pathology and Microbiology, UNMC  Learning Objectives Understand the physiologic differences between children and adults that change the presentation of diseases, paying special attention to reasons why they a...

PEDIATRIC PATHOLOGY I Ana Yuil-Valdes, M.D. Department of Pathology and Microbiology, UNMC  Learning Objectives Understand the physiologic differences between children and adults that change the presentation of diseases, paying special attention to reasons why they are more susceptible to infections Know what percentage of the time a congenital problem has an identifiable etiology and what these common causative factors are Know when in development intrauterine insults are more devastating to developing fetuses and understand why Know the difference between the modes of transmission for perinatal infections and be able to list the common transplacentally acquired pathogens Understand the mechanism and common presentation of respiratory distress syndrome Be able to discuss sudden infant death syndrome  Children are not little adults  Their anatomy and physiology are different.  Airways and blood vessels are not as large  They are more susceptible to infection because their immune system is less efficient.  They do not have the full complement of antibodies that adults do.  Different stages of development preclude to different disorders  The repertoire of tumors they get is different than those in adults. Neonatal/ Perinatal problems Neonatal/Perinatal Causes of Death (9 weeks – Major structures already formed in the fetus continue grow and develop.  Congenital Anomalies – Definitions Malformation Cleft lip – Abnormality of morphogenesis due to an intrinsic problem within the developing structure. – Can be the result of a single gene or chromosomal defect, but are more commonly multifactorial in origin. – Usually during embryonic period  Congenital Anomalies – Definitions Deformation – Abnormality of morphogenesis caused by extrinsic force on a normally developing or developed structure. – Are caused by lack of fetal movement through mechanical or functional factors. – Usually during fetal period  Congenital Anomalies – Definitions Disruption Amniotic bands – Destructive force acting upon an otherwise normal developing structure – Amniotic bands, denoting rupture of amnion with resultant formation of “bands” that encircle, compress, or attach to parts of the developing fetus – Usually during or after fetal period  Malformations  Est. 3% of infants have an apparent significant malformation  Genetic  Environmental  Multifactorial  What causes congenital malformations? 40-60 % unknown. Genetic – Chromosomal abnormalities - usually not hereditary Environmental – Teratogens – Infections Multifactorial  Teratogens Teratogen– a substance/agent that induces birth defects – Examples: alcohol, thalidomide, dilantin, lithium, isotretinoin ~1% of malformations are due to teratogenic exposure The manifestations depend on when in gestation the insult occurs – Embryonic– organogenesis (most susceptible) – Fetal– growth retardation/brain development  Perinatal Infections Again, severity dependent on when the infection happens Obtained two ways: – 1.) Ascending (Transcervical)– from vaginal flora through cervix Most often bacterial (Streptococcus agalactiae) Manifest as chorioamnionitis/funisitis and neonatal pneumonia/sepsis/meningitis Usually a problem at or near delivery  Perinatal Infections Obtained two ways: – 2.)Transplacental– hematogenous spread from mother (“ToRCHEeS”) Toxoplasmosis Rubella CMV Herpes, Hepatitis B, HIV Syphilis – Manifest as a group with fever, hepatosplenomegaly, chorioretinitis, pneumonia, cerebral calcifications, deafness, mental retardation…  Birth Weight Normal – > 2,500 grams (5.5 lbs) Low birth weight (LBW) – ≤ 2,500 grams (5.5 lbs) Very low birth weight (VLBW) – < 1,500 grams (3.3 lbs)  Prematurity vs. SGA vs. IUGR Prematurity = birth before term ( mother supplies increase fluid to deliver same oxygen-> fetal edema Two categories – Immune Hydrops – Nonimmune Hydrops – most common  Immune Hydrops Antibody induced hemolytic disease of the newborn. – Hemolysis  hyperbilirubinemia  kernicterus Almost always due to Maternal anti-D IgG in response to exposure to D+ fetal blood. – Rh immune globulin (anti-D) prophylaxis is administered to D- pregnant women whenever there is a possible risk of fetomaternal hemorrhage.  Nonimmune Hydrops Cardiovascular defects Chromosomal anomalies – Cystic hygroma in Turner Syndrome (45, X) Fetal anemia – Homozygous alpha-thalassemia – Secondary to Parvovirus B19 infection. – (note immune hydrops also results in fetal anemia) Hydrops Fetalis QUESTIONS