LETTER TO EDITOR
Year : 2009 | Volume
: 52 | Issue : 4 | Page : 590--591
Partial hydatidiform mole with a full-term infant
Kajal Kiran Dhingra, Parul Gupta, Vijay Saroha, L Akhila, Nita Khurana
Department of Pathology, Maulana Azad Medical College and Lok Nayak Hospital, Bahadur Shah Zafar Marg, New Delhi-110 002, India
Kajal Kiran Dhingra
D-3-3099 Vasant Kunj, New Delhi 110070
|How to cite this article:|
Dhingra KK, Gupta P, Saroha V, Akhila L, Khurana N. Partial hydatidiform mole with a full-term infant.Indian J Pathol Microbiol 2009;52:590-591
|How to cite this URL:|
Dhingra KK, Gupta P, Saroha V, Akhila L, Khurana N. Partial hydatidiform mole with a full-term infant. Indian J Pathol Microbiol [serial online] 2009 [cited 2020 Jul 13 ];52:590-591
Available from: http://www.ijpmonline.org/text.asp?2009/52/4/590/56137
Hydatidiform mole is characterized by abnormal fetoplacental development and trophoblastic hyperplasia, resulting from genetically abnormal conception when there is excessive paternally derived genetic material. It is classified as complete mole or partial mole (PM) on the basis of differing histopathological and genetic features.  Most pregnancies in which molar change has been reported in association with a live fetus represent a dizygotic twin pregnancy with one complete hydatidiform mole and other normal twin with clearly distinguishable molar regions in the placenta.  We present two cases of singleton pregnancy, in which focal placental molar change was detected, however, the pregnancy ended in phenotypically normal term fetus .
A 28-year-old primigravida presented to the gynecological emergency at 38 weeks gestation with vaginal bleeding. Ultrasound examination revealed a singleton pregnancy with no fetal structural abnormalities and fetal biometry consistent with gestation but numerous placental lucent cysts suggestive of diffuse molar change. A phenotypically normal alive and healthy female infant weighing 2100 gms was delivered by caesarean section. The placentas weighed 560 gms and on sectioning revealed widespread, diffuse vesicle formation [Figure 1]. Light microscopic examination revealed normal villi coexisting with villi showing hydropic change and cistern formation and diffuse circumferential trophoblastic hyperplasia consistent with molar change [Figure 2]A, B.
A 22-year-old unbooked primigravida female presented at 34 weeks gestation with labor pains. A caesarian section was done for non-progress of labor. A healthy female fetus weighing 1900 gms was born without any gross congenital anomaly. The placenta on sectioning revealed multiple grape like vesicles with hydropic change [Figure 1]. The microscopic examination revealed areas of morphologically normal third trimester villi with chorangiosis in some and some showing central cistern formation and with stromal karyorrhectic debris and molar fibrosis [Figure 2]. A diagnosis of partial molar pregnancy with normal fetus was made.
Hydatidiform mole is characterized by abnormal fetoplacental development and trophoblastic hyperplasia due to excessive paternally derived genetic material. 
It is classified into complete mole when there is total replacement of normal placenta by grossly dilated and hydropic villi in the absence of fetus and the incomplete or partial mole showing partial replacement with hydropic villi and visible abnormal fetal parts leading to termination of the pregnancy in first trimester.  Fetus in such cases is rarely alive at the time of diagnosis and often shows gross congenital anomalies associated with triploidy and frequently have a grave prognosis and owing to limited functional placenta circulation and severe intrauterine fetal growth retardation. 
Coexisting molar pregnancy with normal live term fetus as seen in our case is extremely rare excluding cases of multiple conceptions. ,,,, Such an association has been divided into three types. The first and most common is a twin pregnancy with one normal fetus having a normal placenta and another complete mole, second type is a twin pregnancy with normal fetus and placenta and another partial mole and the third and most uncommon occurrence is a singleton normal fetus with partial molar placenta.  The third type of molar pregnancy has been reported only seven times in extensively searched medical literature. Such a fetus should have a normal karyotype to survive to term, though placenta may have variation, from diploidy of the amnion to triploidy of the chorionic villi. However placenta in a partial mole with fetus in a singleton pregnancy results from dispermy and has a triploid karyotype in most cases. 
The complications of coexisting fetus with molar pregnancy include bleeding, persistent gestational trophoblastic disease, preterm labor, late abortion, and severe anemia in the fetus.  The first case we presented had antepartum hemorrhage and the second case had preterm labor. Both the neonates were low for gestational age and on hematological investigation revealed anemia.
Several factors influence the outcome of the fetus in partial molar pregnancy most important being karyotype of the fetus. Both our cases were diploid and had no gross congenital anomaly. Other factors include the size of the molar placenta, the speed of molar degeneration and fetal anemia.  The cases we report probably had sufficient placental circulation to sustain through the first and second trimester, however, had neonatal anemia due to limited placental circulation.
Grossly two types of placental pathology has been described, focal and diffuse partial degeneration.  Our case had a focal molar change allowing fetal survival until term. Extensive sampling of the placenta allowed us to visualize the normal villi. The genetic makeup leading to multiple congenital anomalies as well as the compromised blood supply lead to the diminished fetal survival. Normal fetal outcome is therefore barely known in this condition. 
Prenatal diagnosis of diffuse partial mole is possible by ultrasonography finding showing molar invasion of the normal placenta without clear margin. Antenatal detection of molar pregnancy co existing with a viable fetus should warrant genetic analysis and search for gross malformation of the fetus.  Since both our cases were unbooked and the diagnosis was made in the last trimester, termination of pregnancy was done by caesarian section to deliver a healthy female child. Management of the pregnancy in such rare conditions should be determined on one-to-one basis and the possibility of increased complications should be discussed with the family and prognosis explained.
We report two rare cases exhibiting a partial molar pregnancy and a coexisting normal fetus. Such an occurrence is presumably follows mitotic abnormalities in the early post-fertilization period and represents placental mosaicism. Survival of a fetus to term in the presence of partial mole remains an extremely uncommon occurrence and the two cases presented by us represent an extremely rare outcome of molar pregnancy.
To conclude pregnancies with normal live fetus coexistent and partial molar placenta is extremely rare because of numerous maternal and fetal complications including preeclampsia, hyperthyroidism, heavy vaginal bleeding, persistent gestational trophoblastic disease, preterm labor, fetal abortion, and anemia. We report two cases of singleton pregnancy with partial molar change in the placenta representing placental mosaicism. Since the fetus was normal at birth and the child continues to be growing normally, the abnormal cell population appears to be confined to the placenta. Complete evaluation of the placental tissue is important even in cases with normal fetal outcome as molar changes which might be unsuspected antenataly might affect the future obstetrical outcome.
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