Nonmolar

Nonmolar is a term used in obstetrics and placental pathology to describe gestational tissue or a pregnancy tissue specimen that does not exhibit features of a hydatidiform mole. It is used to distinguish nonmolar tissue from molar pregnancies, which include complete and partial moles, as well as other gestational trophoblastic diseases.

In practice, nonmolar tissue may be obtained after spontaneous abortion, elective abortion, or delivery and can include normal placental villi or villi with nonmolar histology. When a lesion is evaluated histologically, the absence of hydropic changes and the presence of normal villous architecture support a nonmolar diagnosis, whereas hydropic villi with marked trophoblastic proliferation are more consistent with molar tissue. The presence of fetal tissue may be seen in nonmolar pregnancies and can occur in partial moles as well, though partial moles often show triploidy and abnormal villous development.

Diagnosis commonly relies on histopathology augmented by immunohistochemistry. A commonly used marker is p57, which helps distinguish complete mole (typically p57-negative) from nonmolar tissue and partial mole (both usually p57-positive). Molars generally exhibit hydropic villi with diffuse or focal trophoblastic proliferation, whereas nonmolar tissue shows normal villous architecture without these proliferative changes.

Clinical significance centers on prognosis and follow-up. Nonmolar pregnancies or tissue generally have a favorable prognosis with standard obstetric care and do not require the serial hCG monitoring needed after molar pregnancies. In molar cases, careful follow-up is essential to detect persistent gestational trophoblastic disease.