Placenta

• Conditions in which the functional capacity of the placenta is impaired due to altered maternal blood flow to the intervillous space
• Clinical presentation ranges from fetal growth restriction to preeclampsia
• References: Arch Pathol Lab Med 2016;140:698, Pediatr Dev Pathol 2004;7:237

• Uteroplacental insufficiency
• Maternal vascular underperfusion
• References: Arch Pathol Lab Med 2016;140:698, Pediatr Dev Pathol 2004;7:237

• Placenta that is small for gestational age (< tenth percentile of weight)
• Infarction or infarction hematoma, located away from periphery of the disc and of significant size (any infarction in preterm or > 5% of the disc at term)
• Thin umbilical cord (< 8 mm diameter near term), correlating with small disc
• Reference: Placenta 2014;35:696

Contributed by Jonathan L. Hecht, M.D., Ph.D.

• Altered villous morphology (accelerated villous maturation):
  • Villi are small, thin and elongated with increased syncytial knots
  • Accelerated maturation should only be diagnosed based on examination of the villi adjacent to the maternal surface
  • Appearance of accelerated maturation is identical to the normal appearance of the placental region under the fetal surface; this subchorionic zone serves as a good internal control
• Altered villous architecture (distal villous hypoplasia):
  • More easily recognized before 32 weeks of gestation as a paucity of villi in relation to the surrounding stem villi (increased space around the villi)
  • At lower power, this results in a prominence of large stem vessels all the way to the maternal surface
  • In second trimester, there is a loss of the normal gradient of larger immature villi to small mature villi as one scans from mid placenta to maternal surface
• Syncytiotrophoblastic knots (aka Tenney-Parker change):
  • Increase in nuclear clumping and basophilia of the multinucleated cells on the terminal villi
  • Knots should generally only be reported if they are present in every 40x field (30% of the villi) or when prominent in a gestation under 36 weeks
  • Reference tables for syncytial knots are available (Pediatr Dev Pathol 2010;13:305)
• Decidual arteriopathy
• Acute atherosis: collection of intimal foam cells; best seen in the arteries in placental bed biopsies but may extend into the decidual arteries
• Features often cited but not reproducible: islands of fibrin with extravillous trophoblasts; extensive increase in intervillous fibrin, chorion laeve pseudocyst; decidual necrosis
• Reference: Placenta 2014;35:696

Contributed by Jonathan L. Hecht, M.D., Ph.D.

A 34 year old woman who is pregnant with her third child and has 2 kids (G3P2002), with a history of gestational hypertension and diabetes, presents for delivery. Her placenta is sent for pathology. Gross examination reveals a placenta that is small for gestational age, with a 2.1 cm infarction within the central placenta (15% of placenta disc). What feature would be most expected on histopathologic examination?

1. Chronic intervillositis
2. Decreased syncytial knots
3. Increased syncytial knots (Tenney-Parker changes)
4. Maternal floor infarction
5. Normal placenta

C. Increased syncytial knots (Tenney-Parker changes)

Comment Here

Reference: Maternal vascular malperfusion

Accelerated maturation is a feature of maternal vascular malperfusion. What histologic feature is associated with it?

1. Decidual arteriopathy
2. Decreased syncytial knots
3. High placental weight
4. Villlous sclerosis

A. Decidual arteriopathy

Comment Here

Reference: Maternal vascular malperfusion