PARTIAL HYDATIDIFORM MOLE - A COMMON BUT UNDERDIAGNOSED CONDITION - A3-YEAR RETROSPECTIVE CLINICOPATHOLOGICAL AND DNA FLOW CYTOMETRIC ANALYSIS

This retrospective study reports the incidence of hydatidiform mole in a population of 19,457 pregnancies over a 3-year period. During the s tudy period all ''products of conception'' from first and second trime ster abortions were referred for pathological examination. Coded histo logic sections were reviewed using the published histologic criteria f or hydatidiform mole. Ploidy was estimated by DNA flow cytometry. Clin ical data were retrieved from maternal case notes. Thirty-eight cases were confirmed as hydatidiform mole, 10 (26%) as complete mole, and 28 (74%) as partial mole. Twenty-three cases of partial mole (88%) were triploid, and nine of 10 complete moles were diploid. The incidence of hydatidiform mole was 1:512 pregnancies, (complete mole, 1:1,945; par tial mole, 1:695). Only one case (3.5%) of partial mole was suspected clinically. One case of persistent gestational trophoblastic disease o ccurred following a complete mole. No sequelae were encountered follow ing partial mole. We conclude that hydatidiform mole is a common condi tion and the majority of cases are partial moles. Quantitatively impre cise morphologic criteria contribute to the inaccuracy in reporting of partial mole; analysis of ploidy is useful in the evaluation of. prob lem cases. Follow-up of partial mole is warranted because its true bio logical potential is as yet unclear.