Complete hydatidiform mole and normal live birth: a novel case of confined placental mosaicism: Case report

Abstract

Hydatidiform molar change, characterized by abnormal fetoplacental development and placental villous trophoblast hyperplasia, results from genetically abnormal conception, in which there is an excess of paternally derived genetic material. The majority of pregnancies in which molar change has been reported in association with a live fetus represent dizygotic twin pregnancies in which one fertilization results in a complete hydatidiform mole (CM) and the other a normal co-twin. In such cases, there is usually a clear distinction, both sonographically and pathologically, between the molar and non-molar regions of the placenta. We present a singleton pregnancy, with diffuse placental molar change detected prenatally, which resulted in a chromosomally and phenotypically normal female infant at term. Pathological examination revealed the presence of intermixed populations of morphologically normal chorionic villi and villi with the characteristics of CM. Studies of genetic polymorphisms demonstrated that the CM, normal villi and fetus were all derived from the same sperm; the fetus was diploid and biparental whereas the areas of pathological CM were androgenetic and monospermic. We believe this represents the first well-documented case of apparent confined placental mosaicism involving CM and a coexisting normal fetus, which has presumably arisen following mitotic abnormalities in the early post-fertilization period.

Mosaics and moles

“…12 Accordingly, we observed a low frequency of androgenetic cells among single cells from mosaic HMs, suggesting that these cells were most frequent in the syncytiotrophoblastic layer. However, like others, 14 we identified androgenetic markers, only, in DNA isolated from some chorionic villi of a conceptus with both an androgenetic and a biparental cell population, indicating that the androgenetic cells were present both in the trophoblastic layer and in the stroma. In addition, androgenetic cells have been found in amniotic tissue of molar conceptuses.…”

“…Indications of mosaicism/ chimerism with an androgenetic and a biparental cell population have been observed both in HMs, [12][13][14][15][16], present study in placentas displaying PMD, 18,[23][24][25] and in fetuses/children with malformations or growth abnormalities mimicking (part of) the Beckwith-Wiedemann phenotype. [25][26][27][28][29][30] The phenotype seems to correlate with the localization of the androgenetic cells.…”

“…In a pregnancy with an unremarkable fetus and intermixed populations of morphologically normal chorionic villi and villi with molar morphology, an androgenetic cell population would have been overlooked if only normally appearing villi had been analyzed. 14 However, in an abnormal conceptus, it is unlikely that the abnormal tissue would not be examined. Furthermore, in our three moles with balanced biparental alleles, we also observed the balanced biparental alleles when we repeated the analysis in DNA from vesicular villi, only.…”

“…[8][9][10][11] Another possible explanation is the coexistence of two diploid cell populations, one androgenetic and the other biparental. [12][13][14][15][16] In The Danish Mole Project, we have consecutively been collecting samples from HMs since 1986. In the present study, we have subjected 11 diploid HMs showing signs of having biparental genomes to detailed genetic analyses, and found indications that only a minority of these have 'true' biparental genomes, whereas most are mosaics.…”

Rectal hemangioma mimicking uterosacral endometriosis on transvaginal ultrasound examination

“…It often culminates in early spontaneous miscarriage but occasionally results in the birth of an abnormal neonate 1,2 . Triploidy may be the result of either digyny (an extra haploid set from the mother) or diandry (an extra haploid set from the father) 3 .…”