Reappraisal and refined diagnosis of ultrasonography and histological findings for hydatidiform moles: a multicentre retrospective study of 821 patients

Aims Specific identification of a hydatidiform mole (HM) and subclassification of a complete hydatidiform mole (CHM) or partial hydatidiform mole (PHM) are critical. This study aimed to reappraise the diagnostic performance of ultrasonography and histology with a refined diagnosis. Methods This was a retrospective, multicentre cohort study of 821 patients with histologically suspected HM specimens. Refined diagnostic algorithms with p57 immunohistochemistry and short tandem repeat (STR) genotyping were performed and used as the true standard for assessing the diagnostic performance of the original ultrasonography and morphology methods. The diagnostic performance was calculated using accuracy, agreement rate, sensitivity and the positive predictive value (PPV) compared with refined diagnostic results. Results Of the 821 histologically suspected HM cases included, 788 (95.98%) were successfully reclassified into 448 CHMs, 213 PHMs and 127 non-molar (NM) abortuses. Ultrasonography showed an overall accuracy of 44.38%, with a sensitivity of 44.33% for CHM and 37.5% for PHM. The overall classification accuracy of the original morphological diagnosis was 65.97%. After exclusion of the initially untyped HMs, the overall agreement rate was 59.11% (kappa=0.364, p<0.0001) between the original and refined diagnoses, with a sensitivity of 40.09% and PPV of 96.05% for diagnosing CHMs and a sensitivity of 84.98% and a PPV of 45.59% for diagnosing PHMs. The interinstitutional variability of morphology in diagnosing HMs was significant among the 15 centres (range, 8.33%-100.00%, p<0.0001). Conclusion The current diagnosis of HM based solely on ultrasound or morphology remains problematic, and ancillary techniques, particularly p57 immunohistochemistry and DNA genotyping, should be integrated into routine practice as much as possible.