Journal of Postgraduate Medicine Medknow Publications and Staff Society of Seth GS Medical College and KEM Hospital, Mumbai, India ISSN: 0022-3859 EISSN: 0972-2823 Vol. 46, Num. 4, 2000, pp. 291-292

Journal of Postgraduate Medicine, Vol. 46, No. 4, October-December, 2000, pp. 291-292

Images in Radiology

Narlawar RS, Shah J*, Patkar D*

Department Of Radiology, K.E.M. Hospital, Parel, Mumbai and Balabhai Nanavati Hospital*, Vile Parle, Mumbai, India.
Address for Correspondence: Ranjeet S. Narlawar, Department of Radiology, Seth G. S. Medical College and K. E. M. Hospital, Parel, Mumbai - 400 012, India E-mail: drranjeet@hotmail.com

Code Number: jp00097

A 29-year-old primigravida, 22 weeks of gestation, complained of abdominal lump, pain in the abdomen, episodes of vasovagal attacks, headache and intermittent episodes of spotting. On physical examination she was normotensive and fundal height was 20 cm. Two big firm masses were palpable in the lumbar regions bilaterally. The foetal heartbeats were ausculated normally. Antenatal ultrasound examination revealed a live foetus, which had measurements consistent with 22 weeks of gestation. The placenta was anterior in location and showed grade I maturity, without any focal lesion. Another markedly enlarged mass, separate from the anterior normal placenta, with small cystic areas and increased echogenicity was seen along the posterior uterine wall, typically showing "snow storm" appearance. These changes were consistent with hydatidiform molar changes most probably in the second placenta (Figure 1). Two large extrauterine, predominantly cystic masses were also seen in the lumbar regions bilaterally near the fundus of the uterus. They were showing multiple cystic areas within it and measured approximately 15 X 15 cm in size. These were suggestive of theca lutein cysts in both enlarged ovaries in association with the hydatidiform mole (Figure 2). Serum titre of beta-HCG at 22 weeks was 1,20,000 mIU/ml. Chest x-ray, thyroid and liver function tests were normal. Repeat ultrasound at 24 weeks revealed exacerbation of placentomegaly and onset of polyhydramnios. The symptoms continued to increase and the patient underwent spontaneous delivery at 28 weeks of gestation and delivered a baby with weight of 1450 grams. The normal placenta was delivered within 15 minutes after birth and the abnormal posterior placenta was removed subsequently using surgical approach. The histopathology of the abnormal posterior placenta revealed hydatidiform (grapelike, cystic) degeneration of chorionic villi with inadequate vascularisation and abnormal, excessive proliferation of placental trophoblasts. Karyotype of the baby's white cells and mole revealed normal 46-XX chromosomal patterns. Mother's chest radiograph, abdomino-pelvic sonography and serum CA-125 marker study done post partum did not reveal any abnormality. She was not give any chemotherapy.

Discussion

Gestational trophoblastic neoplasia (GTN) represents a spectrum of disorders characterised by abnormal proliferation of pregnancy-related trophoblasts with progressive malignant potential. GTN includes molar pregnancy, invasive mole, choriocarcinoma, and placental site trophoblastic neoplasia with varying degrees of malignant potential. The simultaneous occurrence of GTN and a live foetus is the most common and benign form of GTN, with an estimated incidence of one in 22,000 to one in 1,00,000 pregnancies.¹

Molar pregnancy is broadly of two types, the complete and incomplete (partial). When a hydatidiform mole represents total replacement of normal placenta by grossly dilated, hydropic villi, it is called as "complete mole."² It is usually not associated with foetus or foetal parts, except in the rare event of a coexistent twin pregnancy, as in our case. When an empty ovum is fertilised by single sperm with endoreduplication of the paternal haploid set of chromosomes, 46 XX karyotype is produced (46 YY is lethal).³ "Partial mole" occurs when a normal ovum is fertilised by two haploid sperms with triploid karyotype (69 chromosomes).² In case of partial mole the foetal parts are almost always present but are abnormal and pregnancy does not last usually beyond first trimester. Massive bilateral ovarian enlargement with theca lutein cysts may occur in the presence of mole. This is thought to be reaction to high levels of HCG. Serum HCG levels in molar pregnancy are abnormally elevated, commonly over 1,00,000 mIU/ml.⁴

Patients with molar pregnancy most commonly present in the first or second trimester with vaginal bleeding, rapid uterine enlargement, excessive uterine size for dates, hyperemesis gravidarum or preclampsia before 24 weeks. When a foetus is identified in this syndrome it is rarely alive at the time of diagnosis, and generally manifest a constellation of congenital anomalies associated with triploidy.¹ In the twin gestational syndrome, as in our case, the foetus will have normal diploid chromosomal karyotype.

Ultrasonography plays most important role in this condition. The classic sonographic features of complete molar pregnancy are well known and includes an enlarged uterus containing echogenic tissue that expands the endometrial canal. Hydropic villi within the molar tissue appear as innumerable, diffusely and uniformly distributed cystic spaces ranging in size from few millimeters to 2 to 3 cm.⁵ Sonographic features of partial molar pregnancy are less frequently described and they overlap with other conditions. In partial molar pregnancy, the placenta is excessive in size and contains numerous cystic spaces distributed in a non-uniform manner. A gestational sac is present and frequently is deformed in shape.⁶ A growth retarded foetus is present and show anomalies of triploidy.⁶ Ultrasonography plays an important role in these patients to know the number of foetuses, placentae, sites of placental implantation, changes of molar pregnancy, viability of the foetus, foetal anomalies and associated theca lutein cystic changes in the ovaries. It is important to look for foetal anomalies and placentae carefully since the type of syndrome associated can be predicted and it also helps us to determine the prognosis and treatment options, in such cases.

The literature contains sporadic reports of hydatidiform mole with a coexistent live foetus diagnosed antenatally by ultrasound examination. The majority of these pregnancies appear to fall in one of two distinct syndromes: 1) a "twin gestation", in which it is theorised that one gestation develops normally with normal karyotype while the second undergoes complete molar degeneration (i.e. with 46-XX karyotype) or 2) a "partial mole", described as conceptus with an abnormal foetus with triploid chromosomal karyotype and a single placenta with diffuse hydatidiform changes.⁷

At present there are limited data to guide the antenatal management of twin pregnancy consisting of hydatidiform mole and a coexisting foetus. If severe toxaemia or other medical complication arises, prompt termination of pregnancy may be necessary. Patients who desire to continue pregnancy after such a diagnosis must be cautioned about the potential for severe medical complication. Patients should also be advised that they are at the high risk for developing gestational trophoblastic neoplasia.

References

1. Steller MA, Genest DR, Bernstein MR, Lage JM, Goldstein DP, Berkowitz RS. Natural history of twin pregnancy with complete hydatidiform mole and coexisting fetus. Obstet Gynaecol 1994;83:35-42.
2. Crum CP. Female genital tract. In: Robbins Pathologic Basis of Disease. 5^th ed. Philadelphia: WB Saunders Co; 1994. pp1081-1086.
3. Feinberg RF, Lockwood CJ, Salafia C, Hobbins JC. Sonographic diagnosis of a pregnancy with a diffuse hydatidiform mole and coexistent 46, XX foetus: A case report. Obstet Gynecol 1988;72 (3 Pt 2):485-488.
4. O'Quinn AG, Barnard DE. Gestational trophoblastic disease. In: Current Obstetric and Gynacologic Diagnosis and Treatment. 8^th ed. East Norwalk: Appleton & Lange; 1994. 967-976.
5. Reid MH, McGahan JP, Oi R. Sonographic evaluation of hydatidiform mole and it's look-alike. AJR Am J Roentgenol 1983;140:307-311.
6. Berkowitz RS, Goldstein DP, Bernstein MR. Evolving concepts of molar pregnancy. J Reprod Med 1991;36:40-41.
7. Szulman AE, Surti U. The syndromes of hydatidiform mole. A cytogenetic and morphologic correlations. Am J Obstet Gynecol 1978;131:665-669.

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