True about complete hydatidiform mole is :
**Core Concept**
A complete hydatidiform mole is a type of gestational trophoblastic disease characterized by the abnormal growth of trophoblasts in the uterus, leading to the formation of a non-viable embryo and a mass of grape-like vesicles. This condition typically occurs when an empty egg is fertilized by a single sperm, resulting in an all-paternal diploid genome.
**Why the Correct Answer is Right**
In a complete hydatidiform mole, the karyotype is usually 46,XX, with the extra chromosomes being paternal in origin. This is due to the fertilization of an empty egg by two or more sperms, or the fertilization of a monospermic zygote by a sperm that has an extra set of chromosomes. The lack of maternal genetic material and the presence of an all-paternal genome are key features of this condition. The trophoblastic cells in a complete hydatidiform mole are hyperplastic and invasive, leading to the characteristic grape-like vesicles and potential complications such as hemorrhage and metastasis.
**Why Each Wrong Option is Incorrect**
**Option A:**
* Not applicable, as the question is about complete hydatidiform mole, not partial mole.
**Option B:**
* Not true, as complete hydatidiform mole is typically diploid, not triploid.
**Option C:**
* Not relevant, as the question is about karyotype and genetics, not clinical presentation.
**Clinical Pearl / High-Yield Fact**
Complete hydatidiform mole is a significant risk factor for gestational trophoblastic neoplasia (GTN), a type of cancer that can arise from the abnormal trophoblastic cells. Patients with a history of complete hydatidiform mole should be closely monitored for signs of GTN, including persistent vaginal bleeding, pelvic pain, and abnormal uterine bleeding.
**Correct Answer: D. The karyotype of a complete hydatidiform mole is usually 46,XX, with the extra chromosomes being paternal in origin.**