Diagnosis of hydatidiform moles using p57 immunohistochemistry and chromogenic insitu hybridization: A retrospective study.

Background: Chromogenic in situ hybridization(CISH) and immunohistochemistry analysis for p57 are ancillary studies discriminating partial hydatidiform mole (PHM), complete hydatidiform mole (CHM), and non-molar hydropic abortion (HA).

Objective: It aimed to study CISH with a probe to chromosome 17(CISH17) and chromosome 2(CISH2) discriminating chromosomal ploidy of PHM, CHM, and HA; in addition, their surrogacy value in the evaluation of triploid and diploid in product of conception specimens (POCs) was evaluated.

Materials and methods: 44 statistically significant POCs were selected retrospectively. The Kappa agreement coefficients, sensitivity, specificity, and accuracy with 95% confidence interval (95% CI) were reported.

Results: PHM, CHM, and HA were diagnosed to be 23, 17, and 3 cases based on both CISH2 and CISH17 resulting in their complete discrimination between PHM and HA (23 vs. 3). The Kappa agreement coefficient was 95.4% (p $<$ 0.001) when diagnosing the PHM (23), CHM (20), and HA (1). In addition, the accuracy, sensitivity, and specificity were 95.26% (95% CI: 84.25-99.38), 100% (95% CI: 85.18-100), and 95% (95% CI: 76.18-99.88), respectively. The power analysis on CISH2 and CISH17 tests discriminating between triploid and diploid in POCs was estimated to be 100%.

Conclusion: Based on the current finding, CISH2 and CISH17 enjoyed perfect agreement in diagnosing chromosomal ploidy; in addition, their absolute power discriminating between triploid and diploid revealed that they could be used as surrogate markers for ploidy. Prospective studies on fresh specimens are suggested comparing the CISH method's accuracy with flow cytometry karyotyping and fluorescence in situ hybridization.