Pathology: Placenta Flashcards
Structure of normal placenta (and changes from first to third trimester)
First-trimester: chorionic villi composed of delicate mesh of central stroma surrounded by two discrete layers of epithelium—
• the outer layer consisting of syncytiotrophoblast and
• the inner layer consisting of cytotrophoblast.
Third-trimester: chorionic villi composed of stroma with dense network of dilated capillaries surrounded by markedly thinned-out syncytiotrophoblast and cytotrophoblast
Causes of fetal growth restriction
May result from fetal, maternal, or placental abnormalities:
- Fetal: symmetric growth restriction may result from chromosomal disorders, congenital anomalies, and congenital infections (TORCH = Toxoplasmosis, Others such as syphilis, Rubella, CMV, Herpesvirus)
- Maternal: conditions that result in decreased placental blood flow, common causes include vascular dz (i.e., coagulopathies, pre-eclampsia) and chronic HTN
- Placental: asymmetric, spares the brain; uteroplacental insufficiency may result from umbilical-placental vascular anomalies, placental abruption, previa, thrombosis/infarction, infection, or mult. gestations
Causes of spontaneous abortion/miscarriage
(defined as pregnancy loss before 20 weeks gestation)
- 50% have fetal chromosome anomalies
- maternal endocrine factors: luteal-phase defect uncontrolled DM, others
- physical defects of the uterus can prevent/disrupt implantation: submucosal leiomyoma, uterine polyps, uterine malformations
- systemic disorders affecting the maternal vasculature: antiphospholipid Ab syndrome, coagulopathies, HTN
Major common causes of pregnancy loss in each trimester
1st - chromosomal anomalies
2nd - ascending infection; fetal/maternal anatomic defects
3rd - usually placental insufficiency
Histologic findings of Listeria infection
necrotizing intervillositis
Histologic findings of CMV infection
chronic villitis
Owl eye nuclear inclusions as well as cytoplasmic inclusions (herpes only has nuclear - that’s a distinction)
Also, the cell is HUGE (hence, -megalovirus)
Histologic findings of Parvovirus B19 infection
- viral inclusions in erythroid precursors
- erythroblasts in the lumen of capillaries of placental villi show eosinophilic nuclear inclusions
(the illness is called erythema infectiosum, or fifth disease; presents with body rash and a “slapped cheek” appearance)
Twin-twin transfusion syndrome
a complication of monochorionic twin placentas where the blood is shunted to one twin at the expense of the other; one is underperfused and the other is fluid overloaded; may result in the death of one or both twins
Ectopic pregnancy
a fertilized ovum implanted anywhere it’s not supposed to be; most common site is extrauterine fallopian tubes (~90% of cases)
Placenta previa
a very low lying placenta or a placenta which cover the os; severe hemorrhage can result with cervical dilation and passage of the baby through the birth canal
Placenta accreta
a lack of formation of a normal decidual plate (supposed to sit between the placenta and myometrium), therefore the chorionic villi interdigitate directly with the uterine myometrium. The placenta cannot separate normally following delivery; severe hemorrhage results
Abruptio placenta
premature separation of the placenta prior to delivery, with formation of a retroplacental blood clot; a larger abruption more greatly compromises blood supply to the fetus
Classification of placental invasion into myometrium
- accreta = superficial invasion into myometrium
- increta = deep invasion into myometrium
- percreta = invades through the myometrium
Amnion nodosum
- Multiple yellow-tan superficial amniotic lesions, 0.2 to 0.4 cm and usually near insertion of umbilical cord
- micro: nodules of protuberant eosinophilic fibrinous material with entrapped squamous cells; associated with stratified squamous metaplasia
- seen in placentas affected by oligohydramnios, which may be associated with fetal renal agenesis and pulmonary hypoplasia
- may be due to desquamated skin or membrane injury
Potter’s sequence - features and cause
- features: clubbed feet, pulmonary hypoplasia, and cranial anomalies, like flattened facies and low set ears
- due to oligohydramnios (not enough amniotic fluid)
Preeclampsia
- disorder of pregnancy characterized by HTN and proteinuria
- causes villous ischemia of placenta, fibrinoid necrosis of maternal vessel walls in the decidua
- most placentas are smaller than expected, infarcts and retroplacental hematomas are common
Hydatidiform Mole
- a non-viable fertilized egg that implants into the uterus
- associated with inc. risk of persistent trophoblastic disease (invasive mole) or choriocarcinoma
- check p57 IHC
Complete mole
an egg that has no DNA that gets fertilized; has no embryo, no normal placenta, marked villous enlargement , edema, and circumferential trophoblastic proliferation
all paternal No fetal parts
Snowstorm appearance on ultrasound
Labs: HIGH hCG
Partial mole
an egg with DNA that gets fertilized by 2 sperm (so often ends up as triploid); some villi will appear normal, others swollen, avascular, and grape-like; minimal trophoblastic proliferation
- can have fetal parts
Labs: elevated hCG, not as high as complete mole
Choriocarcinoma
- malignant neoplasm of trophoblastic cells derived from a previously normal or abnormal pregnancy
- histo will see proliferating syncytiotrophoblasts and cytotrophoblasts; mitoses are abundant and sometimes abnormal
- soft, fleshy, yellow-white tumor; usually with large pale areas of necrosis and extensive hemorrhage
- rapidly invasive and metastasizes widely, gets into the underlying myometrium, frequently penetrates blood vessels
- very high hCG levels; responds well to chemo
Placental site nodule or plaque
a rare proliferation of intermediate trophoblast that is microscopic; of no major clinical consequence
Placental Site Trophoblastic Tumor
a rare localized proliferation of intermediate trophoblast that can produce a grossly visible nodule; most are benign but there are rare malignant cases
Necrotizing enterocolitis (NEC)
a complication of premature birth consisting of infarction and transmural necrosis of the bowel, wall becomes perilously thin with impending perforation
-Grossly, submucosal gas bubbles may be seen (pneumonitis intestinalis)
Neonatal respiratory distress syndrome, also known as hyaline membrane disease
- results from reduced surfactant synthesis/storage/release and increased alveolar surface tension
- alternating atelectasis and dilation of the alveoli with eosinophilic thick hyaline
- leads to hypoxemia and CO2 retention and acidosis, pulm. VC and hypoperfusion means endothelial damage and plasma leak into alveoli; fibrin/debris form hyaline membrane
Fetal hydrops
- accumulation of edema fluid in the fetus during intrauterine growth
- causes include CV, chromosomal, fetal anemia, Parvo B19, homozygous alpha-thalassemia, twin-twin, etc.
- Immune hydrops (MCC) = reactions of the Rh antigens and ABO blood groups that occurs in second and subsequent pregnancies; Abs to Rh+ RBCs cause their removal, get anemia, cardiac decompensation, and hydrops, as well as Hgb degradation, bilirubin, jaundice
- Strong association with Turner’s Syndrome (45X)
Cystic hygroma
- a condition in which fluid accumulates in the soft tissues of the neck; looks like a fan around the neck
- characteristically seen, but not limited to, in chromosomal anomalies like 45X
SIDS
- the sudden death of an infant from an unexplained cause (remains unexplained after investigation and autopsy)
Klinefelter syndrome
- XXY
- lost Sertoli cells, lost inhibin, and inc. FSH
- FSH –> aromatase, inc. estrogen
- female SSCs at puberty
Androgen Insensitivity Syndrome (AIS)
- XY phenotypic female
- no testosterone receptor activity, no conversion to DHT, no male structural development
- AMH is present so there’s no female structures, but the distal 2/3 (vagina) and breasts form due to estrogen
Premature ovarian failure
- loss of ovarian function, so dec. estrogen and inhibin feedback results in inc. FSH/LH
- presents as female, >40yo, with amenorrhea; progesterone withdrawal test is negative for bleeding
Polycystic ovarian syndrome (PCOS)
- increased LH increases testosterone and conversion to estrogen
- high LH inhibits FSH; no follicle development and follicle becomes a cyst
- female presents with hirsutism, amenorrhea; progesterone test is positive for bleeding
Turner syndrome
- 45X– monosomy
- presents as lymphedema at birth, primary amenorrhea
- patient is short, shield chest, wide nipples, webbed neck, low hair line, coarctation of aorta, streak ovaries, little estrogen, elevated FSH/LH
Kallman syndrome
- defective production of GnRH
- associated with anosmia (inability to smell)
Inflammation of umbilical vessels (vasculitis) and cord substance (funisitis) occurs in response to infection, and constitutes the fetal or maternal inflammatory response?
Fetal
