Hydatidiform mole coexistent with a twin live fetus: a national collaborative study in Japan

A national collaborative study was conducted in Japan to evaluate the clini cal course and the sequelae of patients with hydatidiform mole coexistent w ith twin live fetus (HMTF). Seventy-two cases of HMTF were diagnosed based on gross appearance and histopathological criteria. In 18 cases, the molar parts were cytogenetically confirmed to be of androgenetic origin (complete mole). The overall incidence of persistent trophoblastic tumour (PTT) in p atients with HMTF was 30.6%, and it increased to 50.0% in the 18 patients w ith proven androgenetic complete mole coexistent with twin live fetus (CHMT F). Among these patients, the mean gestational age at termination of pregna ncy or delivery in those who developed PTT (n 9) and those who did not(n = 9) were 20.6 and 19.4 weeks respectively. The incidence of severe maternal complications was significantly higher in patients who subsequently develop ed PTT (P < 0.05), The rate of subsequent development of PTT in patients wi th CHMTF was found to be considerably higher than in a previous study of pa tients with single complete mole (50 and 12.5% respectively). However, sinc e the risk of malignancy is unchanged with advancement of gestational age, continued pregnancy may be allowed in patients with HMTF provided that seve re maternal complications are controlled and fetal karyotype and developmen t are normal.