Placental Pathology

Question 1

Placenta previa

Answer 1

• Placenta implants on the lower uterine segment or the cervix
• It may completely cover the internal cervical os and can cause fatal hemorrhage during the delivery of the fetus and a cesarean section must be performed

Question 2

Placenta accreta

Answer 2

• Caused by partial or complete absence of the decidua
• The villi adheres directly to the mayometrium thus preventing placental separation at birth
• May result in massive placental bleeding at birth

Question 3

Placental infections

Answer 3

• Can occur by the ascending or hematogenous routes

*ascending: thru the birth canal

*hematogenous route: transplacental route

• Ascending are more common and are usually bacterial in origin and may lead to premature rupture of the membranes and preterm delivery
• Amniotic fluid may be cloudy w/ a purulent exudate
• The chorion-amnion has a polymorphonuclear cell infiltrate w/ edema and congestion of the vessels

Question 4

TORCH infections

Answer 4

• Placental infections
• Infections of toxoplasmosis, rubella, cytomegalovirus, herpes simplex, may have syphilis, TB or listeriosis

Question 5

Chronic villitis

Answer 5

• May be assoc. w/ intrauterine growth retardation and stillbirths
• Cause unknown but may be linked to unknown organisms or abnormal immune reactions
• Found in 1-9% of all placentas
• May be assoc. w/ chronic chorioamnionitis

Question 6

Inflammation of the placental maternal side histology

Answer 6

Question 7

Inflammation of the umbilical vessels histology

Answer 7

Question 8

Listeria infection w/ necrotizing villitis

Answer 8

Question 9

Acute funisitis

Answer 9

• Acute inflammation of the umbilical cord
• Sign of fetal inflammatory response
• Begins as a discrete multifocal process which will coalesce
• See acute inflammation of the umbilical cord

Question 10

Funisitis histology

Answer 10

Question 11

Placental infarct

Answer 11

• Area of villous necrosis due to local obstruction of the maternal uteroplacental circulation
• Fresh infarct is dark red and firmer than surrounding tissue
• Crowding of villi w/ congestion of the villous vessels
• Older lesions appear as a hard, white mass of granular appearance and ghost villi
• May be caused by abruptio placentae
• Infarcts may increase in number and severity in cases of preeclamptic toxemia, hypertension, Rh incompatibility
• High number of infarcts are assoc. w/ a high incidence of neonatal asphyxia, low birth weight and intrauterine demise

Question 12

Old placental infarct gross appearance

Answer 12

Question 13

Ghosts of chronic villi in an infarct histology

Answer 13

Question 14

Gestational trophoblastic disease

Answer 14

• Group of diseases related to normal or abnormal gestation
• Common denominator is the proliferation of the trophoblast
• Disorders differ in appearance and clinical significance:

*complete mole

*partial mole

*invasive mole

*choriocarcinoma

Question 15

Complete mole

Answer 15

• Caused by abnormal gametogenesis and fertilization
• Nuceli contain only paternal chromosomes
• Cytoplasmic DNA is maternally derived
• Most cases have a normal chromosomal number
• Most cases are 46XX, the remainder are 46XY
• Greater incidence in South-east Asia
• Uterus is dispropotionately large for the stage of pregnancy
• Serum hCG levels continue to rise after the 14th week
• Evidence of toxemia is often found such as hypertension, edema, albuminuria
• Hyperthyroidism develops from the thyroid stimulating effects of the molar tissue
• Vaginal bleeding may be present
• Grossly looks like a “bunch of grapes”
• Swollen villi distend the uterus
• Usually see no identifiable embryo, cord or amniotic membranes since the embryo dies so early in development
• Microscopically have trophoblastic hyperplasia and vesicular swelling
• hCG and PLAP present in tissue
• Lack p57 which is a cell cycle inhibitor seen in partial moles
• Expression of myc, ras and sis

Question 16

Complete mole with swollen villi gross appearance

Answer 16

Question 17

Complete mole gross appearance

Answer 17

Question 18

Complete mole-villi in myometrium histology

Answer 18

Question 19

Complete mole with stromal edema and trophoblastic reaction

Answer 19

Question 20

Partial moles

Answer 20

• Accounts for 15-35% of all moles
• Unlike a complete mole this is often assoc. w/ the presence of an embryo
• Volume of placental tissue is relatively normal w/ some vesicular villi
• Many of the villi have an irregular scalloped outline w/ vessels containing mucleated fetal red blood cells
• Fibrosis of the villous stroma is common
• Trophoblastic proliferation is present
• Pos. for p57
• Most are triploid (69XXX or 69XXY)
• Serum hCG levels are elevated but tend to be relatively low
• Risk of development of choriocarcinoma is low

Question 21

Partial mole with fetus gross appearance

Answer 21

Question 22

Partial mole with scalloping of villi histology

Answer 22

Question 23

Invasive mole

Answer 23

• A mole, usually a complete mole, where the villi penetrate deeply into the myometrium and/or its blood vessels
• The penetration may lead to significant hemorrhage
• Uterine perforation may occur
• Vascular invasion may cause trophoblastic nodules to travel outside the uterus to the lungs, brain or spinal cord
• These nodules may in turn hemorrhage
• Differentiated from a usual mole in that it invades the myometrium
• Differentiated from a choriocarcinoma in that it contains villi

Question 24

Choriocarcinoma

Answer 24

• Most aggressive form of gestational trophoblastic disease
• Most cases occur following a complete mole
• Forms soft red, hemorrhagic, round nodular tumor masses
• Clusters of cytotrophoblast separated by masses of syncytiotrophoblast resulting in a dimorphous pattern
• Hemorrhage and necrosis is present
• Villi are absent
• Cells are pos. for hCG and keratin
• If untreated it metastasizes via the hematogenous route to the bowel, lung, brain, liver and kidney
• With appropriate therapy the cure rate is high

Question 25

Choriocarcinoma gross appearance

Answer 25

Question 26

Syncytiotrophoblasts and cytotrophoblasts histology

Answer 26

Question 27

Placental site trophoblastic tumor (PSTT)

Answer 27

• Rare form of trophoblastic disease
• ~75% of cases follow a normal pregnancy
• 5% have had a previous molar pregnancy
• Presents as a myometrial mass which may be well defined or ill defined
• Uterine penetration is deep and perforation can occur
• Contain large trophoblastic cells w/ abundant eosinophilic cytoplasm and nuclear pleomorphism
• Invades the myometrium and blood vessels
• Hysterectomy is usually an adequate treatment but some may be lethal

Question 28

PSTT - cells in myometrium histology

Answer 28

Question 29

PSTT gross appearance

Answer 29