What defines a Complete Hydatidiform mole?

A Complete Hydatidiform mole is a type of gestational trophoblastic disease that is characterized by the presence of abnormal trophoblastic tissue, typically in the absence of normal embryonic development. The defining feature of a Complete Hydatidiform mole is the parental derivation, which is often noted to be 46 XX, indicating that it is formed from the fertilization of an anucleated egg by a sperm (which duplicates its genetic material, leading to triploid formation) or from two sperm fertilizing an empty egg, resulting in androgenesis.

This feature is critical because it highlights that the tissue is derived completely from paternal genetic material, lacking any contribution from maternal DNA, which typically indicates that no normal pregnancy can occur. There is no viable embryo present in a Complete Hydatidiform mole, which leads to the characteristic findings of a hydropic swelling of the chorionic villi and elevated levels of human chorionic gonadotropin (hCG).

In contrast, other options provided do not define a Complete Hydatidiform mole accurately. The presence of a well-circumscribed breast mass, fertilization by one spermatozoa, and the presence of an embryo do not pertain to the distinct genetic and developmental anomalies seen in a