Molar gestations and hydropic abortions differentiated by p57 immunostaining

Classification of molar gestations into complete and partial and their differentiation from hydropic abortions traditionally are accomplished by morphology alone. The process sometimes may be inaccurate or inconclusive. With the availability of p57 immunostaining it may be possible to objectively classify these lesions. We used p57 for the differential diagnosis of hydropic abortions and molar gestations and correlated the findings with the clinical outcome of patients in each category. First, 86 cases were originally classified by histomorphology into hydropic abortion (42) and molar gestations (23 complete and 21partial). Based on the pattern of p57 staining the cases were reclassified into 45 hydropic abortions, 15 partial moles and 26 complete moles (3 cases with previous diagnosis of complete mole based on morphology were reclassified as hydropic abortion). Clinical follow-ups ranged from 6-24 months and showed persistent trophoblastic disease in 8 cases (31%) of complete moles and 3 cases (20%) of partial moles (p = 0.47). No hydropic abortion cases demonstrated persistent trophoblastic disease. One patient with partial mole developed choriocarcinoma. This study confirms that p57 objectively distinguishes hydropic abortions from molar gestations (partial and complete moles). This differentiation is clinically relevant since patients with hydropic abortions do not need to be followed while patients with molar gestations do.