[Epidemiologic and clinicopathologic studies of partial hydatidiform mole].

To determine the epidemiological and clinicopathological characteristics of partial hydatidiform mole (PHM), a comparative study of PHM and complete hydatidiform mole (CHM) was performed in molar patients who were entered in the regional registry of Niigata Prefecture and/or who were admitted for treatment at Niigata University Hospital. The results obtained are as follows. 1. From 1971 to 1988, 2,290 hydatidiform moles (HMs) were documented in the registry. The incidence of HM was annually decreasing with an almost constant ratio to the total number of pregnancies. Since 1986, the number of PHM was rising with an inverse decrease in CHM. One hundred fifty one of 1,923 CHM (7.9%) had persistent trophoblastic disease (PTD), but on the other hand only 6 of 367 cases PHM (1.6%) had. 2. In 275 patients treated in our hospital from 1971 to 1990, 134 of 240 with CHM (55.8%) and 6 of 35 with PHM (17.1%) experienced PTD. Of 6 PTD patients following PHM, 3 had invasive mole, 1 metastatic mole and 2 post molar persistent hCG, but no choriocarcinoma. 3. The recent study of DNA analysis in molar tissue revealed that one case, which had been diagnosed as PHM, coexisted with CHM and non-molar pregnancy.