Partial molar appearance of the placenta in trisomy 13.

Although molecular studies have shown that more than 90% of partial moles are secondary to diandric triploidy, there are some rare cases with tetraploidy or unspecified aneuploidies. We diagnosed 3 cases of partial mole presentation during the 2nd trimester of pregnancy with multiple fetal abnormalities. In all 3 cases, cytogenetic studies showed trisomy 13. We present the cases and discuss the clinical and pathological aspects of the conditions presented as partial moles.