Placental mesenchymal dysplasia

Case contributed by Manisha Langar
Diagnosis possible

Presentation

A primipara woman presented, for a routine ultrasound. No history of hyperemesis gravidarum or bleeding per vagina.

Patient Data

Age: 20 years
Gender: Female
ultrasound

A single viable fetus was seen in cephalic presentation, with average gestational age of 20 weeks and 2 days. No gross congenital anomaly was seen.

A normal placenta was seen along the anterior wall of the uterus, lying in upper segment.

A well defined discoid, echogenic, vesicular lesion, approximately measuring 145 mm x 92 mm,  interspersed with multiple small cysts was seen along the posterior wall of the uterus (hydatidiform mole-like picture). Peripheral vascularity was seen in the lesion, on color Doppler interrogation. However, no internal vascularity was evident. The lesion appeared to be continuous with the normal placenta, posterosuperiorly. Umbilical cord seen inserting into the normal placenta anteriorly.

The myometrium-lesion interface was well defined and no myometrial invasion was seen.

Both ovaries were normal. No significant follicle/cyst was seen in either of the ovaries.

Case Discussion

Placental mesenchymal dysplasia (PMD) is a benign condition that can be confused with a molar pregnancy by ultrasound scanning and gross examination. Unlike molar pregnancy, the incidence of PMD is rare and has a reported incidence of 0.02%.

It is a rare placental anomaly characterized by placentomegaly and grape-like vesicles resembling molar pregnancy. PMD usually features a normal fetus. It is also called pseudo-partial mole. But fetal IUGR and IUD are quite common with PMD. 

Distinguishing PMD from its mimics, especially molar pregnancy is important for preventing unnecessary termination of pregnancy.

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