Introduction to Paediatric Pathology Flashcards
List the pathogenetic mechanisms leading to paediatric pathologies.
(a) Defects of pregenesis — intrinsic defects within gametes, aneuploidy
(b) Defects of blastogenesis — mutations, teratogens, infections [usually
severe]
(c) Defects of organogenesis — mutations, teratogens, infections, physical factors
(d) Defects of phenogenesis — mutations, teratogens, infections, physical factors
Briefly discuss causes of defects of pregenesis.
👶 Defects of spermatogenesis e.g. low sperm count, poor motility, or abnormal morphology affect fertility.
👶 Defects of oogenesis may result in aneuploidy, leading to conditions like Down syndrome.
👶 Fertilization defects e.g. fertilization by more than one sperm can result in an abnormal zygote with extra sets of chromosomes, usually leading to early embryonic loss.
👶 Cleavage Abnormalities: Irregularities in the initial cell divisions can result in uneven cell sizes or failed implantation.
👶 Genetic Mutations: Inherited or spontaneous mutations can disrupt normal development.
👶 Environmental factors like radiation, toxins, and infections can interfere with early embryonic development.
Further notes:
Pregenesis refers to the early stages of embryonic development, including gametogenesis, fertilization, and the initial stages of cell division.
Aneuploidy and disruptions result in defects of blastogenesis and phenogenesis. What are causes of disruptions?
(a) Problems with vascular development
(b) Anoxia (lack of oxygen)
(c) Infection
(d) Radiation
(e) Amniotic entanglement
(f) Teratogenic drugs
What is spontaneous abortion?
Spontaneous abortion refers to the natural loss of a pregnancy before the fetus is viable (able to survive outside the womb). It’s estimated to affect 70-80% of all pregnancies.
What are the stages of pregnancy loss before recognition?
👶 Before implantation: Approximately 30% of pregnancies are lost before the embryo implants in the uterus.
👶 After implantation but before recognition: Another 30% of pregnancies are lost after implantation but before the mother realizes she is pregnant.
What are the differences between early and late spontaneous abortion?
👶 Early spontaneous abortion: Pregnancy loss in the embryonic period (first 8 weeks).
👶 Late spontaneous abortion: Pregnancy loss between 9-18 weeks.
List causes of abortion.
👶 Aneuploidy/Polyploidy: abnormal number of chromosomes or multiple sets of chromosomes
👶 Infections
👶 Luteal phase deficiency: This is a condition where the luteal phase of the menstrual cycle is shorter than normal, leading to insufficient production of progesterone, which is crucial for maintaining pregnancy.
👶 Thrombophilias: These are disorders that increase the risk of blood clots, which can affect the placenta and lead to pregnancy loss.
👶 Anomalies of uterine development: Structural abnormalities in the uterus can interfere with the implantation and growth of the embryo.
👶 Poor maternal nutrition: Deficiencies in essential nutrients like zinc and folate can impact fetal development and increase the risk of abortion.
👶 Increasing maternal age: As maternal age increases, the risk of chromosomal abnormalities and other complications that can lead to pregnancy loss also increases.
Growth Disorganisation (GD) describes various stages of developmental abnormalities in embryos. Briefly describe each of the four stages of Growth Disorganisation.
👶 GD 1: An intact chorionic sac with no evidence of an embryo.
👶 GD 2: A chorionic sac with an embryo (1-4 mm) that has no recognizable external features and lacks retinal pigment.
👶 GD 3: Elongated, smooth embryos (less than 10 mm) without distinct morphological hallmarks but with retinal pigment.
👶 GD 4: An embryo with recognizable head, trunk, and limb buds, but with severe developmental inconsistencies.
Discuss conditions that may result in late spontaneous abortions.
(1) Neural tube defects: These are severe birth defects of the brain and spine that occur when the neural tube does not close properly during early pregnancy.
(2) Amnion rupture sequence: This is a rare condition where the amniotic sac ruptures early in pregnancy, leading to complex fetal anomalies.
(3) Posterior cervical cystic hygroma: This is a fluid-filled sac that forms on a baby’s neck due to a blockage in the lymphatic system. It can be associated with genetic conditions and can lead to complications. [Image 1] [Image 2]
(4) Abdominal wall defects: These are birth defects where the abdominal organs protrude through an abnormal opening in the abdomen. The two main types are omphalocele and gastroschisis.
Molar pregnancies are a type of gestational trophoblastic disease. Compare complete and incomplete molar pregnancies.
👶 Complete Hydatidiform Mole
A complete hydatidiform mole occurs when an egg that has lost its genetic material is fertilized by one or two sperm. As a result, all the genetic material comes from the father. This leads to the formation of abnormal placental tissue that swells and forms fluid-filled cysts, resembling a cluster of grapes. In this type of molar pregnancy, there is no fetus.
[Image 1] [Image 2] [Image 3] [Image 4]
👶 Partial Hydatidiform Mole
A partial hydatidiform mole happens when an egg is fertilized by two sperm, resulting in an embryo with an extra set of chromosomes (69 instead of the normal 46). This leads to the development of both normal and abnormal placental tissue. There may be a fetus, but it is typically malformed and cannot survive.
[Image 5] [Image 6] [Image 7] [Image 8]
Further notes:
[6-minute video]: Normal Histology of the Placenta
List five types of developmental defects.
(1) Malformations: A structural defect resulting from an intrinsic problem during embryonic development, caused by failure of embryonic cell proliferation and/or differentiation.
(2) Disruptions: Structural anomalies caused by extrinsic factors that interfere with normal development. Example: amniotic band syndrome, where bands of amniotic tissue constrict parts of the fetus.
(3) Dysplasias: Abnormal cellular organization leading to structural anomalies.
(4) Deformations: Structural anomalies caused by mechanical forces. Example: clubfoot, where the position of the fetus in the womb causes abnormal foot positioning.
(5) Sequences: a series of developmental anomalies that result from a single initial defect or mechanical factor. Example: Potter sequence - oligohydramnios results in compression of the fetus, leading to facial deformities, limb contractures and underdeveloped lungs.
List physical agents that can be teratogenic.
Radiation, hypoxia, hyperthermia, mechanical forces, environmental pollutants
List infectious agents that can be teratogenic.
👶 rubella
👶 HHV [6, 7]
👶 Zika Virus
👶 parvovirus
👶 syphillis
👶 toxoplasmosis
List heavy metals that can be teratogenic.
lead, methylmercury, lithium, cadmium, arsenic, chromium
List maternal diseases that can be teratogenic.
diabetes, starvation, myasthenia gravis, endocrinopathies, systemic lupus erythematosus (SLE)