Malignant trophoblastic neoplasms with different modes of origin

Extrauterine epithelioid trophoblastic tumour and its somatic carcinoma mimics: short tandem repeat genotyping meets the diagnostic challenges

AIMS

While epithelioid trophoblastic tumour (ETT) primarily arises from the uterus, cases have been increasingly documented at extrauterine sites, originating from an ectopic gestation or presenting as a metastatic tumour, leading to the major differential diagnosis of somatic carcinoma with trophoblastic differentiation. The precise separation of a gestational trophoblastic tumour from its somatic carcinoma mimics is highly relevant and crucial for patient management and prognosis.

METHODS AND RESULTS

We summarise the clinicopathological and molecular features of four challenging epithelioid malignancies presenting at extrauterine sites, with ETT as the main differential diagnosis. All four tumours demonstrated histological and immunohistochemical features overlapping between a somatic carcinoma and an ETT, combined with inconclusive clinical and imaging findings. Serum beta-hCG elevation was documented in two cases. Short tandem repeat (STR) genotyping was performed and was informative in all cases. The presence of a unique paternal allelic pattern in the tumour tissue confirmed the diagnosis of ETT in two cases with an initial consideration of either somatic carcinoma or suspicion of a gestational trophoblastic tumour. The presence of matching genetic profile with the patient's paired normal tissue was seen in two other cases (both initially considered as ETT), confirming their somatic origin, including one metastatic triple-negative breast carcinoma and one primary lung carcinoma.

CONCLUSIONS

Diagnostic separation of ETT at an extrauterine site from its somatic carcinoma mimics can be difficult at the histological and immunohistochemical levels. STR genotyping offers a robust ancillary tool that precisely separates ETT from somatic carcinomas with trophoblastic differentiation.

Genotyping diagnosis of gestational trophoblastic disease: frontiers in precision medicine

Investigations in recent decades have exploited tissue DNA genotyping as a powerful ancillary tool for the precision diagnosis and subclassification of gestational trophoblastic disease. As lesions of gestational origin, the inherited paternal genome, with or without copy number alterations, is the fundamental molecular basis for the diagnostic applications of DNA genotyping. Genotyping is now considered the gold standard in the confirmation and subtyping of sporadic hydatidiform moles. Although a precise diagnosis of partial mole requires DNA genotyping, prognostic stratification according to distinct genetic zygosity in complete moles has recently gained significant clinical relevance for patient care. Beyond hydatidiform moles, DNA genotyping has fundamental applications in the diagnosis or prognostic assessment of gestational trophoblastic tumors, in particular gestational choriocarcinoma. DNA genotyping provides a decisive tool in the separation of gestational trophoblastic neoplasia from non-gestational counterparts/mimics of either germ cell or somatic origin. The FIGO/WHO prognostic scoring scheme requires ascertaining the precise index gestational event and the time interval between the tumor and index gestation, where DNA genotyping can provide highly relevant information. With rapid acquisition of molecular diagnostic capabilities in the clinical practice, DNA genotyping has become closely integrated into the routine diagnostic workup of various forms of gestational trophoblastic disease.

Precision genotyping diagnosis of lung tumors with trophoblastic morphology in young women

Trophoblastic differentiation has been previously described in somatic carcinomas at different primary sites, including the lung. Lung carcinomas with trophoblastic morphology presenting in women during the reproductive years pose a unique diagnostic challenge due to their overlapping microscopical and immunophenotypical features with metastatic choriocarcinoma of gestational origin. Distinction between the two entities is paramount as they require different chemotherapeutic regimens and have a markedly different prognostic outlook. Here we report a series of three female patients (ages 37-48 years) presenting with lung masses. Two of the three patients were noted to have elevated serum beta-hCG levels at the time of their presentation, while serum beta-hCG was not evaluated preoperatively in the third patient. None of them had a clinical history of molar pregnancy or gestational trophoblastic neoplasia. Core biopsies of the lung masses were performed in two patients and one patient underwent a wedge resection, showing poorly differentiated carcinoma in all cases with scattered multinucleated giant cells, hemorrhage, and necrosis. Beta-hCG immunostain was performed in two cases and showed diffuse immunoreactivity. Clinical history and imaging studies were not conclusive in any of the cases to rule out a gestational origin. Short tandem repeat genotyping analysis was performed to compare the allelic patterns between tumor and normal tissues and revealed identical profiles in one case, consistent with somatic origin, and unique paternal alleles in two cases, confirming metastatic gestational choriocarcinoma. The patient with primary somatic lung carcinoma died of disease within 15 months despite chemotherapy, while both patients with gestational choriocarcinoma responded well to chemotherapy and are alive without evidence of disease. Our cases illustrate the diagnostic pitfalls of lung tumors with trophoblastic differentiation in young women. Genotyping analysis offers precise diagnostic distinction between primary lung carcinoma and gestational choriocarcinoma with major therapeutic and prognostic implications for the patients.

The clinical characteristics and early detection of postpartum choriocarcinoma

OBJECTIVES

This study aimed to identify the clinical and demographic characteristics and prognosis of patients with conditions diagnosed with postpartum choriocarcinoma based on the International Federation of Gynecology and Obstetrics 2000 prognosis scoring system or based on pathologically confirmed choriocarcinoma and to analyze the patients' clinical symptoms for early detection of this disease.

METHODS/MATERIALS

Between January 1983 and August 2013, 24 consecutive women with postpartum choriocarcinoma were treated at 2 hospitals. Data on clinical and demographic characteristics, including initial presenting symptoms, type of antecedent pregnancy, fetal complications, and prognosis of these patients, were analyzed. According to the time interval between the previous delivery and the onset of disease, patients were divided into 2 groups: the short and long interval groups.

RESULTS

The most common symptom among the 24 patients with postpartum choriocarcinoma was irregular vaginal bleeding (14/24); in some cases, bleeding was caused by metastatic foci (7/24). Massive genital bleeding causing emergency hysterectomy and several obstetric complications, such as unknown severe fetal anemia and fetal growth retardation, was only observed in the short interval group. The overall primary remission rate was 91.7%.

CONCLUSIONS

The most common symptom of patients with postpartum choriocarcinoma in the short and long interval groups was genital bleeding, and the overall prognosis may be improved by introduction of an appropriate chemotherapy regimen. Careful pathological examination of the placenta is needed in cases of fetomaternal hemorrhage, unknown fetal anemia, and abnormal obstetric events, including premature delivery, still birth, and infantile growth retardation, for the early detection of intraplacental choriocarcinoma.

Discovery of a cell: reflections on the checkered history of intermediate trophoblast and update on its nature and pathologic manifestations

In 1976, a series of 12 cases describing a lesion that had previously not been well characterized was reported as "trophoblastic pseudotumor of the uterus." Up until that time rare reports of the lesion had classified it most often as an unusual type of sarcoma associated with pregnancy. All patients in that series were alive and well except for one who died from complications of a uterine perforation occurring at the time of a diagnostic curettage. Thus, it appeared to be a benign neoplasm but subsequently it was found that some exhibited malignant behavior and the tumor was renamed "placental site trophoblastic tumor." A variety of observations pointed to an origin in a distinctive cell of the placental site, designated "intermediate trophoblast," which physiologically is seen in the normal implantation site. Subsequently, another subset of intermediate trophoblast cells originating from the chorion laeve have been shown to give rise to the placental site nodule/plaque, a well-circumscribed and usually microscopic incidental finding as well as the epithelioid trophoblastic tumor, its putative malignant counterpart. The initial description of "trophoblastic pseudotumor" opened a new area of research which brought to bear immunohistochemical and molecular genetic analyses that eventually has led to new insights in the diverse morphologic changes occurring in early placentation and also led to the development of a new classification of trophoblastic tumors and tumor-like lesions.

Clinical analysis of 21 cases of nongestational ovarian choriocarcinoma

INTRODUCTION

The objective of the study was to investigate the clinical characters, diagnosis, treatment, and prognosis of nongestational ovarian choriocarcinoma.

METHODS

A retrospective analysis was done on 21 patients with nongestational ovarian choriocarcinoma treated in Peking Union Medical College Hospital from January 1985 to October 2008. All patients' conditions were diagnosed by histopathologic examination; in 3 of them, the diagnosis was confirmed by DNA polymorphism analysis at 12 short tandem repeat loci.

RESULTS

Correct diagnosis was achieved in only 3 patients before initial treatment. All patients received standard multiple-drug combined chemotherapy and underwent an operation. The mean number of chemotherapy courses for each patient was 10. Of the 21 patients, 16 achieved complete remission, and 4 obtained partial remission; 1 died. In a median follow-up of 71.4 months, the 5-year overall survival rate was 79.4%.

CONCLUSIONS

The early diagnosis of nongestational ovarian choriocarcinoma is expected to be improved. DNA polymorphism analysis is a useful tool in determining the origin of ovarian choriocarcinoma. The prognosis is optimistic if managed with standard multiple-drug chemotherapy combined with surgical treatment.

Pathogenesis of choriocarcinoma: clinical, genetic and stem cell perspectives

Choriocarcinoma is a unique malignant neoplasm composed of mononuclear cytotrophoblasts and multinucleated syncytiotrophoblasts that produce human chorionic gonadotrophin. Choriocarcinoma can occur after a pregnancy, as a component of germ cell tumors, or in association with a poorly differentiated somatic carcinoma, each with distinct clinical features. Cytogenetic and molecular studies, predominantly on gestational choriocarcinoma, revealed the impact of oncogenes, tumor suppressor genes and imprinting genes on its pathogenesis. The role of stem cells in various types of choriocarcinoma has been studied recently. This review will discuss how such knowledge can enhance our understanding of the pathogenesis of choriocarcinoma, enable exploration of novel anti-choriocarcinoma targeted therapy and possibly improve our insight on embryological and placental development.

Gestational trophoblastic neoplasia—pathogenesis and potential therapeutic targets

Gestational trophoblastic neoplasia comprises a unique group of human neoplastic diseases that derive from fetal trophoblastic tissues and represent semiallografts in patients. This group is composed of choriocarcinoma, placental-site trophoblastic tumour, and epithelioid trophoblastic tumour, and many forms are derived from the precursor lesions, hydatidiform moles. Although most patients with gestational trophoblastic neoplasia are cured by chemotherapy and tumour resection, some patients suffer from metastatic diseases that are refractory to conventional chemotherapy. Therefore, new therapeutic regimens are needed to reduce the toxic effects associated with current chemotherapy and to salvage the occasional non-operable patients with recurrent and chemoresistant disease. Until the fundamental biology of gestational trophoblastic neoplasia becomes more clearly understood, development of a new treatment will remain empirical. This review will briefly summarise the recent advances in understanding the molecular aetiology of this group of diseases and highlight the molecules that can be potentially used for therapeutic targets to treat metastatic gestational trophoblastic neoplasia.

A pure nongestational choriocarcinoma of the ovary diagnosed with short tandem repeat analysis: case report and review of the literature

Nongestational pure choriocarcinoma of the ovary is a very rare germ cell tumor. Except in women before menarche, determination of the origin is very difficult without genetic analysis. We present a pure nongestational choriocarcinoma arising in the left ovary of a 19-year-old woman. Following surgery, pathologic findings of the tumor demonstrated pure choriocarcinoma without combination of other germ cell tumor elements. We confirmed its nongestational origin by DNA polymorphism analysis at 15 short tandem repeat loci. Multiple courses of chemotherapy with methotrexate, etoposide, and actinomycin-D were effective for this case. DNA polymorphism analysis is useful to determine genetic origin in pure choriocarcinoma of the ovary

Intraplacental choriocarcinoma in a term placenta with both maternal and infantile metastases: a case report and review of the literature

BACKGROUND

Intraplacental choriocarcinoma is rare, and usually results in maternal metastasis at the time of diagnosis. Intraplacental choriocarcinoma involves both mother and infant is extremely rare. There was only one case report of intraplacental choriocarcinoma with confirmed metastases involving both the mother and the infant.

CASE

We describe a second case of intraplacental choriocarcinoma in a term placenta with both maternal and infantile metastases. Grossly, the primary lesion of the placenta resembled an old infarct. Microscopically, clusters of malignant trophoblasts arose from residual normal chorionic villi and infiltrated into the intervillous spaces. Both the mother and the infant received chemotherapy and were alive without disease after one year's follow-up.

CONCLUSION

The optimal treatment for intraplacental choriocarcinoma is controversial. However, aggressive chemotherapy is suggested for patients with metastatic disease.

Placental site trophoblastic tumor: A study of 55 cases and review of the literature emphasizing factors of prognostic significance

OBJECTIVE

The placental site trophoblastic tumor is a rare form of gestational trophoblastic disease. Fifteen percent of reported cases have been fatal, but predicting behavior in individual patients has been challenging.

METHODS

The clinical, gross and histopathological features of 55 cases and 180 cases in the literature were analyzed for their effect on survival and in relation to tumor stage.

RESULTS

The 55 patients in our series were 20 to 62 (average 32) years of age. The tumors occurred on an average of 34 months after the last known gestation. 84% were stage I, 2% stage II, 5% stage III, and 9% stage IV. Serum levels of human chorionic gonadotropin (hCG) were elevated (average 691 mIU/ml) in 77% of the cases. The tumors were on average 5 cm in greatest dimension and were composed microscopically of infiltrative sheets of intermediate (extravillous) trophoblastic cells. The mitotic rate ranged from 0 to 20 (average 5.0) per 10 high power fields. The follow-up interval averaged 4.6 years. Eight patients (15%) died from metastatic tumor, and nine additional patients had metastases or a recurrence but were alive at last contact. The most common metastatic sites were the lungs, liver, and vagina.

CONCLUSIONS

Significant factors associated with adverse survival in the present series were age over 35 years (P = 0.025), interval since the last pregnancy of over 2 years (P = 0.014), deep myometrial invasion (P = 0.006), stage III or IV (P < 0.0005), maximum hCG level > 1000 mIU/ml (P = 0.034), extensive coagulative necrosis (P = 0.024), high mitotic rate (P = 0.005), and the presence of cells with clear cytoplasm (P < 0.0005). Only stage and clear cytoplasm were independent predictors of overall survival, while stage and age were the only independent predictors of time to recurrence or disease-free survival. In the literature, factors associated with survival were stage (P < 0.005), interval from preceding pregnancy of over 2 years (P = 0.029), previous term pregnancy (P = 0.046), high mitotic rate (P < 0.0005), and high hCG level (P = 0.037).

Primary omental gestational choriocarcinoma ascertained by deoxyribonucleic acid polymorphism analysis

BACKGROUND

Abdominal choriocarcinoma is extremely rare. It is important to examine whether the disease is primary or metastatic and gestational or non-gestational.

CASE

A 26-year-old nulli-gravid woman underwent laparoscopy for presumed ectopic pregnancy. The uterus, ovaries and fallopian tubes surrounded by hemoperitoneum were unremarkable. A hemorrhagic 7-cm-sized tumor was identified on the greater omentum and excised. Histology was consistent with choriocarcinoma. Analysis of human leucocyte antigen (HLA) gene polymorphism on deoxyribonucleic acid (DNA) demonstrated that tumor DNA contained both HLA locus antigens of patient and of her husband. Clinical remission was achieved with six courses of chemotherapy.

CONCLUSION

To our knowledge, this is the first reported case of choriocarcinoma that occurred primarily on the omentum ascertained to be of gestational origin by DNA polymorphism analysis.

Placental site trophoblastic tumor of the uterine cervix occurring from undetermined antecedent pregnancy

A cervical polyp complicated by severe hemorrhage was removed from a 43-year-old Japanese woman (gravida 0), who had undergone tubectomy on the right side 10 years previously. The polyp was diagnosed by immunohistochemical studies as placental site trophoblastic tumor of the cervix, but no metastatic foci were found in any other uterine site. The tumor was further demonstrated by PCR polymorphisms to possess two genomic DNA of the patient and her husband. Serum beta-hCG and urinary hCG titers were both low, which rapidly fell to 0.8 mIU/mL after a total hysterectomy and remained 0.2 mIU/mL after dismission. She has been uneventful for 3 years.

Genetics and molecular markers in gestational trophoblastic disease with special reference to their clinical application

Gestational trophoblastic disease (GTD) encompasses a diverse group of lesions with specific cytogenetic and molecular pathogenesis. Although cytogenetic studies have been extensively reported, the molecular pathogenesis is poorly understood. We will summarize some of the recent molecular observations and correlate them with the pathology of GTD. Complete mole is androgenetic in origin. Thus, if a monoallelic contribution can be shown in complete mole, this would render the gene susceptible to functional inactivation by 'one-hit' kinetics. Alternatively, uniparental transmission of genes that are subject to parental imprinting in humans would impair their regulation. Loss of NECC1 expression, biallelic deletions at the critical (7p12-7q11.23) region and enhanced H19 expression in choriocarcinoma would reflect the genetic features exhibited by the putative forerunner, complete mole. In addition to the unique genetic features shown in GTD, alterations in gene expression profiles accompanied by malignant conversion of trophoblasts would facilitate the development of choriocarcinogenesis from complete mole. With recent advances in molecular techniques, further work is still necessary to provide a better understanding and useful markers for persistent trophoblastic disease. These may provide useful prognostic indications that may guide the different diagnosis of GTD.

Placental site trophoblastic tumor arising from antecedent molar pregnancy

OBJECTIVE

Placental site trophoblastic tumor (PSTT) is a rare form of gestational trophoblastic disease. Little is known about its pathogenesis and natural history.

METHODS

This report describes two cases that arose in patients with documented complete hydatidiform moles and summarizes the antecedent prenatal histories of PSTTs based on a detailed Medline literature analysis.

CASES

A 28-year-old, G(2)P(2) female had a live, 12-week gestation fetus and a coexisting molar pregnancy. Her hCG levels dropped promptly from 1.5 million to 23,273 IU/ml after termination, but rose shortly thereafter together with the onset of recurrent vaginal bleeding. Curettage revealed persistent mole. Persistently elevated hCG led to hysterectomy disclosing a fundal PSTT. The second case was that of a 48-year-old, G(2) woman who presented with symptoms of preeclampsia, hyperthyroidism, and elevated hCG. Curettage yielded a complete hydatidiform mole. Although the hCG level decreased for a short period, it soon increased despite treatment with methotrexate. A second curettage revealed a PSTT.

DISCUSSION

A Medline literature analysis of PSTT, which consists almost entirely of individual cases and several small series, disclosed that PSTT is preceded in 61% of cases by normal term pregnancy, 12% molar pregnancy, 9% spontaneous abortion, 8% therapeutic abortion, and 3% with ectopic pregnancy, stillbirths or preterm delivery. No information is known in 7%. This report describes two additional cases of PSTT preceded by complete molar pregnancy.

CONCLUSIONS

PSTT is a well recognized, but uncommon form of gestational trophoblastic disease. Although little is known about its pathogenesis, it is preceded not uncommonly by an abnormal pregnancy, including a molar pregnancy.

NECC1, a candidate choriocarcinoma suppressor gene that encodes a homeodomain consensus motif

We isolated a candidate choriocarcinoma suppressor gene from a PCR-based subtracted fragmentary cDNA library between normal placental villi and the choriocarcinoma cell line CC1. This gene comprises an open reading frame of 219 nt encoding 73 amino acids and contains a homeodomain as a consensus motif. This gene, designated NECC1 (not expressed in choriocarcinoma clone 1), is located on human chromosome 4q11-q12. NECC1 expression is ubiquitous in the brain, placenta, lung, smooth muscle, uterus, bladder, kidney, and spleen. Normal placental villi expressed NECC1, but all choriocarcinoma cell lines examined and most of the surgically removed choriocarcinoma tissue samples failed to express it. We transfected this gene into choriocarcinoma cell lines and observed remarkable alterations in cell morphology and suppression of in vivo tumorigenesis. Induction of CSH1 (chorionic somatomammotropin hormone 1) by NECC1 expression suggested differentiation of choriocarcinoma cells to syncytiotrophoblasts. Our results suggest that loss of NECC1 expression is involved in malignant conversion of placental trophoblasts.

Molecular genetic analysis of placental site trophoblastic tumors and epithelioid trophoblastic tumors confirms their trophoblastic origin

Trophoblastic tumors represent a unique group of human neoplasms because they are derived from fetal tissue. Except for choriocarcinoma, the neoplasms that develop from human trophoblast are poorly characterized. Placental site trophoblastic tumors and epithelioid trophoblastic tumors are thought to arise from intermediate (extravillous) trophoblasts based on histopathological studies, but direct molecular evidence of a trophoblastic origin has not been established. In this study, we performed molecular analysis in an attempt to confirm their presumable trophoblastic origin. We demonstrated that such tumors contain a Y-chromosomal locus and/or new (paternal) alleles not present in adjacent normal uterine tissue in all 31 informative cases. Loss of heterozygosity was found in 60% of tumors and all 42 tumors assessed contained wild-type K-ras. All of the trophoblastic tumors were heterozygous in at least 1 of 10 single-nucleotide polymorphism markers studied in contrast to homozygosity in all 10 single-nucleotide polymorphism markers in most complete hydatidiform moles indicating that these tumors are not related to complete hydatidiform moles. This study provides the first molecular evidence that placental site trophoblastic tumors and epithelioid trophoblastic tumors are of fetal (trophoblastic) origin.

Genetic origin of malignant trophoblastic neoplasms analyzed by sequence tag site polymorphic markers

OBJECTIVE

To study the causative conception of malignant gestational trophoblastic neoplasms (GTNs), we analyzed malignant GTNs by microsatellite PCR markers.

METHOD

DNAs extracted from 12 malignant GTNs were subjected to PCR for five different chromosomal locations.

RESULT

Of the 7 cases after a complete mole (CM), 5 were derived from androgenesis, but the remaining 2 were from normal fertilization. Of the 5 cases after nonmolar pregnancies, 2 placental site trophoblastic tumors had alleles from both parents. Of the other 3 choriocarcinomas, 1 was from normal fertilization after spontaneous abortion but 2 originated from androgenesis, suggesting that 1 was from a CM prior to the antecedent abortion, transforming after a long interval.

CONCLUSION

By combining the previous cases with these, our analysis of 39 cases demonstrated that trophoblastic neoplasms can arise from at least three different modes of origin (androgenesis, normal fertilization, and parthenogenesis), and antecedent pregnancy is not always identical to the causative conception. Placental site trophoblastic tumors might have different machinery for carcinogenesis because of the predominance of paternal and maternal contributions. In addition, a long dormancy of trophoblasts before malignant transformation, especially for those originating from normal fertilization, was also suggested.

Twin pregnancy consisting of 46, XY heterozygous complete mole coexisting with a live fetus

Complete hydatidiform mole and coexistent fetus (CMCF) is a rare occurrence and is associated with an increased risk of persistent gestational trophoblastic diseases. The aim of this study was to reveal a potential risk factor and to determine optimum management of CMCF cases. Molar tissues are cytogenetically divided into two types, homozygous and heterozygous. The molar tissue of our case showed a 46, XY heterozygous complete mole. Genomic DNA was analyzed by the polymerase chain reaction using sets of unlabelled forward and Cy-5-labelled reverse primers for DNA marker loci. The patient developed persistent trophoblastic disease (PTD) with lung metastasis. Since 1980 there have been 13 reports (including our case) that cytogenetically revealed CMCF and clarified the clinical outcome. Nine of the 16 CMCF cases before 21 weeks of gestation and seven of the 12 CMCF cases after 22 weeks of gestation developed PTD. The incidence of PTD from CMCF was not related to the gestational age at termination or delivery. There were 10 case reports that analyzed the zygosity of a mole, heterozygous or homozygous. Two of six homozygous and three of four heterozygous moles in CMCF cases developed PTD. A heterozygous mole is thought to be a high risk factor for the incidence of PTD. Cytogenetic study is clinically useful for the optimum management of CMCF cases.

Pathogenesis of placental site trophoblastic tumor may require the presence of a paternally derived X chromosome

Placental site trophoblastic tumor (PSTT) is a neoplastic proliferation of intermediate trophoblasts that invades the myometrium at the placental site after a pregnancy. Less than 100 cases have been reported. Information of the sex assignment of the antecedent gestation is available in 21 cases: 18 of these were female. To explore this interesting phenomenon, we have determined the sex chromosome composition of the tumor tissue preserved in paraffin blocks for five new cases of this condition. The last documented gestational event included a normal vaginal delivery of female infants in three cases, normal vaginal delivery of an infant of unknown sex in one case and a molar gestation in one case. Using the X-linked human androgen receptor (AR) gene as a polymorphic marker, we showed that in all five cases the tumor had a likely XX chromosomal composition; and in four cases it was possible to determine that one of the X chromosomes was of paternal origin. In one case, the paternal X chromosome showed no polymorphism to either maternal X chromosomes. In addition, sensitive semi-nested PCR failed to show a human Y chromosome element in any of the five cases of PSTT. Overall, of 21 cases from the literature and 5 cases of ours, 89% (23 of 26) showed an XX genomic composition in PSTT, either by history or genetic analysis. These results suggest that most PSTT were derived from the antecedent female conceptus and were likely to have possessed a functional paternal X chromosome. Methylation status analysis at the AR locus was performed in the three PSTT in which the paternal X chromosome was identifiable. In two cases, the paternal AR locus was hypomethylated while the corresponding maternal locus was hypermethylated. The methylation status of other loci was not investigated. Collectively, sex chromosome analysis of five cases of PSTT with literature support suggests a unique genetic basis for the development of PSTT that involves the paternal X chromosome. Although largely speculative, an active paternal X chromosome may be of importance in the pathogenesis of PSTT.

Isochromosome 1q as the sole chromosomal abnormality in two fetal teratomas. Possible trisomic or tetrasomic zygote rescue in fetal teratoma with an additional isochromosome 1q

An isochromosome of the long arm of chromosome 1 leading to tetrasomy 1q was detected as the sole chromosomal aberration in two cases of fetal teratoma arising from the oral cavity. This type of teratoma is extremely rare and has seldom been investigated cytogenetically. Studies of DNA markers in the tumor, normal fetal skin, and parental cells demonstrated that in both cases the additional 1q material was of maternal origin. In one of the patients, the teratoma had maternal 1q marker alleles that were not found in the fetal body cells. This implies that the tumor was not derived in a direct way from the fetal body tissue; instead, the chromosomally-normal fetus might be the result of some trisomic or tetrasomic zygote rescue mechanism.

Gestational choriocarcinoma whose responsible pregnancy was a complete hydatidiform mole identified by PCR analysis with new sequence tagged site primers

We report a case where the pregnancy responsible for a gestational choriocarcinoma was not the antecedent pregnancy or the second normal term delivery, but a complete hydatidiform mole that had advanced to clinically invasive mole. This responsible pregnancy was identified by polymerase chain reaction analysis (PCR). PCR analysis was performed by using five new sets of sequence-tagged site (STS) primers on four chromosomes (chr. 1, D1S225; chr. 3, D3S1744; chr. 12, D12S1090; chr. 18, D18S849 and D18S877). The constitution of alleles of choriocarcinoma was shown to be almost identical with that of the husband on every marker. The allele patterns of choriocarcinoma on D3S1744 and D12S1090 were not observed with DNA from the patient. The band pattern originating from molar DNA was also identical with those of the husband and choriocarcinomas on D18S849 and D1S225.

Recent advances in gestational trophoblastic disease

Advances in the last 20 years have led to a better understanding of the process of gestational trophoblastic disease (GTD), and consequently, to improved diagnosis, management, and prognosis. Patients with GTD should be registered at a trophoblastic disease center for follow-up, and those with persistent disease should receive chemotherapy, methotrexate, and folinic acid for low-risk disease, and EMACO (etoposide, actinomycin-D, methotrexate, vincristine, and cyclophosphamide) for high-risk disease, without loss of fertility. Most patients with relapsing or resistant disease can be treated effectively with surgery and/or cisplatin in EP/EMA (etoposide, platinum-etoposide, methotrexate, actinomycin-D) combination.

Intraplacental choriocarcinoma associated with viable pregnancy: pathologic features and implications for the mother and infant

Choriocarcinoma arising in the placenta, or intraplacental choriocarcinoma, has seldom been reported, particularly in the absence of maternal metastases. Reluctance to diagnose choriocarcinoma in the presence of chorionic villi can delay diagnosis; however, timely diagnosis of choriocarcinoma is prognostically important, both for the mother and infant. We report the clinicopathologic findings in five mothers and infants in whom choriocarcinoma was identified in the placenta. None of the mothers had a history of gestational trophoblastic disease in previous pregnancies. Three placentas were similar with a single small lesion grossly suggesting a small infarct; microscopically these consisted of infarcted areas surrounded by choriocarcinoma. These three mothers were unusual in that none had metastatic choriocarcinoma; two were treated with chemotherapy and remained disease-free; the third was lost to follow-up shortly following delivery. The remaining two mothers had known pulmonary metastases at time of delivery. One of these latter two placentas contained a large marginal lesion microscopically identified as choriocarcinoma. The fifth placenta had rare microscopic foci of choriocarcinoma, and sheets of necrotic choriocarcinoma were identified in "blood clot" submitted with the placenta. In four of the five cases the choriocarcinoma appeared to be arising from otherwise normal chorionic villi, and in no case was there invasion of the villous stroma. All of the infants survived, and none had evidence of choriocarcinoma. These cases support the concept that choriocarcinoma associated with otherwise normal pregnancy arises in the placenta and may be more common than reported.

Genetic differentiation of complete hydatidiform moles coexisting with normal fetuses by short tandem repeat-derived deoxyribonucleic acid polymorphism analysis

OBJECTIVE

We applied deoxyribonucleic acid polymorphism analysis on the basis of differences in the number of short tandem repeat sequences to genetically differentiate dizygotic twins with complete hydatidiform moles and normal fetuses from partial moles presenting a similar appearance.

STUDY DESIGN

Six pregnant women exhibiting apparent moles and coexisting fetuses were the subjects of this study. Eight polymorphic loci including short tandem repeat sequences were amplified by polymerase chain reaction from deoxyribonucleic acid of peripheral leukocytes of parents, umbilical cord, grossly normal placenta-villi, and molar tissue. The segregation of alleles among samples were determined by comparing band patterns on polyacrylamide gels.

RESULTS

In all 6 cases amplifications of polymorphic loci provided sufficient information to determine the parental origin. At informative loci the alleles of cord and placenta-villi were transmitted from both patients and husbands whereas molar tissue had only paternal alleles. These allele segregations indicated 2 different genetic origins, namely, normal parental for a fetus and androgenetic for molar tissue, and thus the diagnosis of dizygotic twins with a complete hydatidiform mole and a normal fetus was made. Additionally, the molar component was defined as a heterozygous mole in 2 cases.

CONCLUSION

Short tandem repeat-derived deoxyribonucleic acid polymorphism analysis was demonstrated to be a useful and precise procedure for the differential diagnosis of a complete hydatidiform coexisting with a normal fetus and the determination of its zygosity as well.