Complete hydatidiform mole with retained maternal chromosomes 6 and 11

Area of Science:

• Reproductive Medicine
• Genetics
• Pathology

Background:

• Distinguishing complete hydatidiform mole (CHM) from partial hydatidiform mole (PHM) and nonmolar specimens is vital for clinical management and risk assessment of persistent gestational trophoblastic disease.
• Immunohistochemical analysis of p57 expression and molecular genotyping are key ancillary techniques for accurate diagnosis.

Observation:

• CHMs typically exhibit androgenetic diploidy and lack p57 expression due to the absence of maternal DNA.
• A rare case of morphologically typical androgenetic diploid CHM with aberrant diffuse p57 expression was identified.
• Molecular genotyping confirmed androgenetic diploidy with retained maternal copies of chromosomes 6 and 11, explaining the aberrant p57 expression.

Findings:

• Loss of p57 expression is characteristic of CHM, distinguishing it from PHM and nonmolar specimens.
• The identified case demonstrates that aberrant p57 expression can occur in CHM, necessitating molecular confirmation.
• Combined p57 immunohistochemistry and molecular genotyping are essential for accurate molar specimen diagnosis.

Implications:

• Misclassification of CHM with aberrant p57 expression as PHM can underestimate the risk of persistent gestational trophoblastic disease.
• Routine use of p57 immunohistochemistry and molecular genotyping for suspected hydatidiform mole specimens is recommended.
• Genome-wide analysis may help identify imprinted genes influencing mole phenotype and behavior.