MORPHOLOGICAL AND IMMUNOHISTOCHEMICAL EVALUATION OF HYDATIDIFORM MOLE IN A TERTIARY HEALTH INSTITUTION (2008-2014)

Abstract

Background/Introduction: Hydatidiform mole is the commonest Gestational Trophoblastic
Diseases (GTD) worldwide. The different types bear different risk for persistence and
malignant transformation with the Complete Mole variant accounting for about 20-30% risk
while the Partial Hydatidiform Mole (PHM) has a much lower risk of 2.5-7.5%. There are
classical characteristic morphologic features used to distinguish between these two entities
especially during the second trimester. Early presentation however, poses diagnostic
variability using morphologic features alone. This study therefore aimed at assessing the use
of p57 immunohistochemistry as a proven marker to differentiate Complete Hydatidiform
Mole (CHM) from Partial Hydatidiform mole.
Aim and Objectives:
The objective of this study was to classify Gestational trophoblastic diseases received in the
institution as well as evaluate hydatidiform mole morphologically and
immunohistochemically using p57 marker.
Materials and Methods: Formalin fixed paraffin embedded (FFPE) tissue blocks and
corresponding archival routine haematoxylin and eosin (H&E) stained slides of all the cases
of GTD from the products of conception and other histologic diagnosis of GTD within the
study period were retrieved and reclassified according to WHO 2012 classification and Horn
et al criteria. Further immunohistochemical classification using p57 antibodies was applied
on all the Hydatidiform moles. Data was analysed using SPSS 16 to associate p57
expression and the morphologic features of Hydatidiform mole.
Results: Sixty six cases of Gestation Trophoblastic Diseases were studied and it represented
11.4% of all the products of conception recorded during the review period. Complete
Hydatidiform mole, Partial Hydatidiform mole and Gestational Choriocarcinoma accounted
for 80.3%, 3% and 16.7% respectively. The incidence of hydatidiform moles was 4.5/1000
deliveries. The age range for all the molar pregnancies was 15-50 years with majority seen
in the fourth decade of life. The overwhelming majority presented at second trimester
accounting for 72.7%. The use of WHO 2012 and Horn et al morphologic criteria
significantly changed 64.3% of previously diagnosed PHM to CHM. This number was
further increased to 85.7% with application of p57 immunohistochemistry.
Conclusion: Adequate knowledge and reliable use of morphology would help significantly
in the diagnosing and classifying majority of Hydatidiform Mole especially in a low
resourced environment. That notwithstanding, the application of P57 would certainly help
resolve unsure cases of CHM, in particular early CHM.

MORPHOLOGICAL AND IMMUNOHISTOCHEMICAL EVALUATION OF HYDATIDIFORM MOLE IN A TERTIARY HEALTH INSTITUTION (2008-2014)