SA Pathology - Women’s and Children’s Hospital, ADELAIDE, AUSTRALIA

Presentation Abstract

MOLAR PREGNANCY: The legend of the 365 children

Molar pregnancy is an abnormal pregnancy which carries an increased risk of gestational trophoblastic disease, including choriocarcinoma. Correct diagnosis of complete mole (CM) is required so that complete evacuation of the uterus follow-up beta-HCG levels and if required, further treatment can be undertaken. Reliance on an H&E diagnosis alone can be problematic as not all cases display typical histology, and other conditions that do not carry the same level of risk such as partial mole (PM) and other chromosomal abnormalities may present with very similar histological appearances. Diagnosis of CM is facilitated by the use of p57 immunostaining and in many cases no further investigation is required. In conjunction with histology, routine cytogenetics or FISH on paraffin sections can diagnose triploidy which is consistent with PM.

The genetic cause of molar pregnancy is the over-representation of paternal genetic material. Both chromosome sets are paternal in CM with no maternal component, while there are two paternal sets and one maternal set in PM. Genetic studies using microsatellite markers are capable of determining the parental origin of the genetic material, distinguishing between CM, PM and non-molar pregnancies. In conjunction with histology and p57 staining, microsatellite testing was used for complex cases which include discordant histology and p57 results, patchy p57 immunochemistry staining, and confirmation of partial mole or non-molar pregnancies.

In less than 1% of the molar cases, a gene mutation altering genome methylation pattern is the cause (an autosomal recessive disorder). It presents as a CM clinically and histologically. However, it is p57 positive and has both paternal and maternal chromosomes. This type of mole can be recurrent (in the same woman) or familial (in the sisters of the woman). DNA sequencing is the method of choice to make a diagnosis and guide clinical management.

Given genetic testing is an important part of diagnosis of molar pregnancy, fresh tissues should be kept in case genetic testing is required.



A/Prof Lynette Moore Biography

A/Prof Lynette Moore graduated from Flinders University and trained in Histopathology at the Adelaide Children’s Hospital and the IMVS. After her training, she moved to the UK and was appointed Consultant Paediatric Pathologist at St Mary’s Hospital and Pendlebury Children’s Hospital in Manchester. She returned to Adelaide and to the Women’s and Children’s Hospital as Senior Consultant Pathologist and was Head of Department at SA Pathology (WCH) from 2007-2015. Her interests are in placental pathology, fetal dysmorphology, paediatric renal pathology and paediatric tumours.

Dr Sui Yu Biography

I am a genetic pathologist of SA Pathology based at the Women’s and Children’s Hospital in Adelaide. I supervise a cytogenetic laboratory and a molecular genetics laboratory focusing on paediatric genetic disorders and reproductive related genetic disorders including molar pregnancies. The challenge over the last few years has been to work with other subspecialties and to apply the appropriate genetic tools to address the complex clinical questions. It has been a pleasure to work closely with Surgical Pathology at WCH on the molar pregnancy project.

Shanna Suwalski Biography

Shanna is a senior medical scientist with SA Pathology and attained a Science degree with honours in Genetics from the University of Adelaide. Beginning her career in the field of pre-implantation genetic diagnosis, she has been working in the Cytogenetics Laboratory at the Women’s and Children’s Hospital here in Adelaide for the last 14 years, and is a Member of the Human Genetics Society of Australasia. She is passionate about the application of both conventional and molecular cytogenetics to improve patient clinical outcomes.