Medical brain notes 42

  Gestational Trophoblastic Neoplasia Gestational trophoblastic neoplasia  (GTN) is a rare G  variation of pregnancy of unknown etiology and usu-ally presents as a benign disease called  hydatidiformmole  (molar pregnancy).  GTN is a clinical spectrum that  includes all neoplasms that derive from abnormal placental (trophoblastic) proliferation.  There are two varieties ofmolar pregnancies, complete mole (no fetus), and incom-plete mole (fetal parts in addition to molar degeneration.)  Persistent  or  malignant disease  will develop in approxi-mately 20% of patients with molar pregnancy. Persistent or malignant GTN is responsive to chemotherapy.   Key clinical features of GTN include: (1) clinical presentation as pregnancy, (2) reliable means of diagnosis by pathognomonic ultrasound findings, and (3) a specific tumor marker (quantitative serum  human chorionicgonadotropin [hCG]).  Persistent GTN may occur with an...

  EPIDEMIOLOGY The incidence of molar pregnancy varies among different national and ethnic groups. The highest incidence occurs among Asian women living in Asia (1 in 200 pregnancies). The incidence in the United States is approximately 1 in 1500 pregnancies, with a recurrence rate of 1% to 2%. It is more common in older women. It is associated with low dietary carotene consumption and vitamin A deficiency. Partial moles are associated with history of infertility and spontaneous abortion.

  HYDATIDIFORM MOLE   A hydatidiform mole includes abnormal proliferation of the syncytiotrophoblast and replacement of normal pla-cental trophoblastic tissue by  hydropic placental villi.Complete moles  do not have identifiable embryonic orfetal structures.  Partial moles  are characterized by focal trophoblastic proliferation, degeneration of the placenta, and identifiable fetal or embryonic structures.   The genetic constitutions of the two types of molar pregnancy are different  (Table 41.1). Complete moles have chromo-somes entirely of paternal origin as the result of the fer-tilization of a blighted ovum by a haploid sperm that reduplicates, or rarely, fertilization of a blighted ovum with two sperm.  The karyotype of a complete mole is usually 46XX.The fetus of a partial mole is usually a triploid.  This consists ofone haploid set of maternal chromosomes and two haploid sets of paternal chromosomes, the consequence of di-spermic f...

  MALIGNANT GESTATIONAL TROPHOBLASTIC NEOPLASIA   Postmolar or  persistent GTD  is only one of the many forms of malignant GTD. Although invasive moles are his-tologically identical to antecedent molar pregnancies while invading the myometrium,  choriocarcinomas  are a malig-nant transformation of trophoblastic tissue. Instead of hydropic chorionic villi, the tumor has a red granular appearance on cut suction and consists of intermingled syncytiotrophoblastic and cytotrophoblastic elements with many abnormal cellular forms. Clinically, choriocarcino-mas are characterized by rapid myometrial and uterine-vessel invasion and systemic metastases resulting from hematogenous embolization. Lung, vagina, central ner-vous system, kidney, and liver are common metastatic loca-tions. Choriocarcinoma may follow a molar pregnancy, normal-term pregnancy, abortion, or ectopic pregnancy. In the United States, choriocarcinoma is associated with approximately 1 in 150,000 pre...

  PLACENTAL SITE TUMORS   Placental site tumor is a rare form of trophoblastic disease. The tumor is comprised of monomorphic populations of intermediate cytotrophoblastic cells that are locally inva-sive at the site of placental implantation. The tumor only secretes small amounts of hCG, and can be better fol-lowed by human placental lactogen levels. This tumor is rarely metastatic and is much more resistant to standard chemotherapy. Hysterectomy as initial therapy is often curative