Placenta

Question 1

Benign mimics of malignancy

Answer 1

Placental site nodule Exaggerated placental site

Question 2

Nearly normal placenta

Answer 2

Amnion nodosum Meconium exposure Chorioamnionitis Maternal vasculopathy Fetal thrombotic vasculopathy Placenta accreta Infections Normal POC!

Question 3

Transplacental infections

Answer 3

Viral/protozoa: ToRCH - toxo, rubella, CMV, HSV Bacterial: Listeria (necrosis, microabscesses), syphilis

Question 4

Ascending infection (chorioamnionitis)

Answer 4

Group B Strep Fusobacterium (filamentous bacteria on amnion - Warthin-Starry) Candida

Question 5

Critical values (report to clinician)

Answer 5

Specific infections (eg CMV/HSV, Listeria, Candida) Genetic disorders: mesenchymal dysplasia, inborn error of metabolism Malignancies Severe fetal thrombotic vasculopathy

Question 6

Trophoblastic tumours

Answer 6

Choriocarcinoma: bHCG+ syncytiotrophoblast

Implantation site IT (hPL+)

• exaggerated placental site: ki67<1%
• placental site trophoblastic tumour: ki67>10% (+mitoses, sheetlike, fibrin)

Chorionic IT (p63+, hPL +/-)

• placental site nodule: cyclin E-
• epithelioid trophoblastic tumour: cyclin E+ (+large, cellular, necrosis)

Question 7

Hydropic abortus vs partial mole (morphology)

Answer 7

Partial mole: Dual population of villi Central cisterns Irregular outlines Trophoblast inclusions Fetal parts (incl fetal RBCs)

Question 8

Partial mole vs complete mole (morphology)

Answer 8

Complete mole: Single population of villi Prominent trophoblast hyperplasia Hypercellular blue myxoid stroma Stromal karyorrhexis No fetal parts

Question 9

Ihc and ploidy for moles

Answer 9

Non-molar: biparental diploidy, p57+

Partial mole: diandric triploidy, p57+

Complete mole: androgenetic diploidy, p57- (look at villous trophoblast and stroma only!)

Question 10

Maternal (decidual) vasculopathy

Answer 10

Atherosis: fibrinoid necrosis, lipid macrophages, chronic inflammation, thrombi Absence of physiologic conversion: muscular arteries in decidua Both are markers of pre-eclampsia (+/- HELLP, fatty liver)

Question 11

Fetal thrombotic vasculopathy

Answer 11

Early: karyorrhexis Later: fibrotic avascular villi NB: needs to be diffuse to be clinically significant (2 foci 15 villi, or 45 villi total) May indicate cord obstructions, or fetal thrombophilia.

Question 12

Fetal thrombotic vasculopathy DDX

Answer 12

Intrauterine fetal demise Inflammatory response to amniotic fluid infection Chronic villitis