Lack of genetic association between exaggerated placental site reaction and placental site trophoblastic tumor.

Exaggerated placental site (EPS) reaction is a reactive or an exuberant physiologic process involving intermediate trophoblasts infiltrating the underlying endomyometrium at the implantation site. Sharing similar cytological and immunohistochemical features with the tumor cells of placental site trophoblastic tumor, a biological link between the 2 lesions can be speculated. Because placental site trophoblastic tumor has a unique sex chromosomal requirement in its genome that requires a paternal X chromosome (i.e. a female antecedent gestation), we investigated whether EPS carries the similar genetic profile by DNA genotypic analysis. Twenty cases of EPS were reviewed and analyzed by AmpFlSTR Identifiler polymerase chain reaction amplification system (Applied Biosystems, Inc., Foster City, CA). The genetic profile of all cases demonstrated unique paternal alleles to that of the paired maternal tissue, confirming the trophoblastic origin of EPS. The presence of an XY genome (male) was identified in 11 cases (55%), and an XX genome (female) was seen in the rest of 9 cases (45%). Therefore, EPS is a trophoblastic lesion that can arise from either male or female gestations. The assignment of sex chromosomes in our study (XY, 55% and XX, 45%) does not support a neoplastic association between placental site trophoblastic tumor and EPS.