Recent Advances in the Pathology and Classification of Ovarian Germ Cell Tumors

In recent years, our knowledge of ovarian germ cell tumors has increased, and their classification has evolved. The introduction of cisplatin-based chemotherapy and the discovery of tumor markers, including alpha-fetoprotein and human chorionic gonadotropin, have dramatically changed the clinical outlook for most of these patients. In this review, recent advances in the classification and pathology of ovarian germ cell tumors are discussed. Where appropriate, comparisons are made with testicular germ cell tumors. The last section of the article discusses the pathogenesis of germ cell tumors. This review will emphasize the articles written in the last 10 years and those that have significantly advanced our knowledge of germ cell tumors in past decades.

[Malignant trophoblastic tumors (MTT) treated in the years 1955-2004 in trophoblastic disease center in the Czech Republic (TDC-CZ): clinical-pathological features, curability, typing, pathogenesis]

OBJECTIVE

Clinical- pathological features, typing, curability and pathogenesis of malignant tumors of trophoblast (MTT).

DESIGN

A retrospective analysis.

SETTING

Trophoblastic Disease Center in the Czech Republic (TDC-CZ), Mother and Child Care Institute, 3rd Medical Faculty, Charles University, Prague.

METHODS

Revision of 379 MITT cases treated at TDC-CZ and comparison of their histological picture with developmental stages of orthologic trophoblast from the standpoint of MTT typing and pathogenesis. The determination of curability of different histological types and risk stages (RS) used in TDC-CZ and a comparison with RS axccording to FIGO, WHO and NIH. Differentiation of undifferentiated choriocarcinoma (CH-Und) alias Epitheloid Trophoblastic Tumor (ETT) from the given cohort of MIT and establishment of its clinical and biological properties, curability and formal pathogenesis.

RESULTS

Three hundred and seventy nine MTT cases were classified into 5 histological types onthe basis of analogy with developmental stages of 7 to 14 days old trophoblast. 1: typical "classical" choriocarcinoma - No Special Type (CH-NST), which forms more than 80% of MTT. Moreover, the degree of differentiation of tumorous trophoblast and its prevailing (cytological) type made it possible to define other 4 types, i.e.: 2: CH-syncytio-trophoblastic (CH-Syn), representing 3.8%; 3: CH-cytotrophoblastic CH-Cyt with 3.3%; 4: CH-dissociated (CH-Dis), representing 6%; 5: CH-undifferentiated (CH-Und) with 6.8%. Mortality due to MIT of all mentioned types reached 94% until 1963, decreased to 43% until 1980 and has been 5.8% in the period of 1981-2004. In the latter period of time (1981-2004), mortality due to CH-Cyt proved to be 40%, that due to CH-Dis being 11%, and CH-Und 18%, though. Mortality of s.c. Placental Site Trophoblastic Tumor, which includes our CH-Cyt and CH-Dis therefore forms 21.4%. We have been using four RS in TDC-CZ. The following outline includes only the main features: 1st RT includes CH-NST < 30mm limited to uterus in connection with mole. 2nd RS includes CH-NST > 30mm after birth. 3rd RS includes CH-NST with multiple metastases outside GIT and CNS and MTT with the CH-Cyt, Dis, Und component < 75%. 4th RS includes CH-NST with metastases in CNS or GIT. MTT with CH-Cyt Dis, Ned component < 75% with metasteses and MTT with the same components > 75% In the last 23 years 1st RS and 2nd RS includes 85 % of all MTT in the TDC-CZ and curability is 100%. In the 3rd RS curability decreases to 64.3% and decreases to 55.6% in the 4th RS. According to FIGO classification the 1st RS forms 48%, 2nd RT represents 17% and 100% curability applies for both of them. 3rd a RS includes 20% of 100% curability, 3rd bc RS forms 10% with 67% curability and 4th abc RS includes 5 % with 50% curability. In using the WHO classification with four RS, their percentage representation is similar to our classification with similar curability; nevertheless the 1st RS and 2nd RS did not detect almost 8% of MTT, which ended with exitus. 3rd RS according to FIGO is overestimated in view of 100% curability and the abc degree in 1st and 2nd RS are only of theoretical significance and irrelevant for the choice of treatment. The closest results comparable with our classification were those of NIH. A very careful clinical-pathological analysis of 25 CH-Und-ETT, detected among 379 MTT revealed that CH-Und-ETT is anaggressive malignant form of CH, which is best derived from undifferentiated 7-8 days old trophoblast. It is insidious for its seemingly primary extragenital symptomatology in seven out of 25 cases, low hCG values and poor sensitivity to chemotherapy.

CONCLUSION

1) The comparison of histological pictures of 379 MTT with developmental stages of orthologic trophoblast of 7-14 days old embryo was the basis for classification of 5 types of choriocarcinoma (CH): 1. Differentiated CH "No Special Type" (CH-NST), 2. Syncytiotrophoblastic CH (CH-Syn), 3. Cytotrophoblastic CH (CH-Cyt), 4. Dissociated CH (CH-Dis), and 5. Non-differentiated CH (CH-Und); 2) We have determined their percentual (and absolute) occurrence in the group of 379 MTT treated in CTN in the years 1955-2004. 3) We have described biological properties of individual types of CH and established the way they influence curability. 4) Four degrees of risk (RS) were specified in relation to 7 types of risk factors observed (1. size of tumor, 2. type of preceding pregnancy, 3. interval from pregnancy to the diagnosis, 4. histological type of CH, 5. number of metastases, 6. localization of metastases, 7. values of hCG). It has become obvious how RS influenced curability of CH (1st and 2nd RS forms 85% of all CH's and their curability is 100% (!), 3rd and 4th RS are represented in 15% and their curability is 64% in the 3rd RS and 55% in the 4th RS. 6) The curability reached in CTN was compared with that determined according to FIGO, WHO and NIH, respectively. The results proved to be similar, but in case of FIGO the 3rd degree was overestimated and the degrees abc in the 1st and 2nd RS were of theoretical importance only, therefore being of no values for the choice of treatment. Low and medium score according to WHO did not detect 8% of women who had died. The CH curability according to RS, having been recommended by NIH and used in the American Centers was virtually the same as our results. 7) It has been proved that the histological type of CH significantly influenced the determination of RS in the given patient. 8) CH-Und-ETT represents the least differentiated form of MTT, in other words choriocarcinoma. This is associated with a low production of HCG, mostly between 10(1) and 10(3) mIU/ml. 9) Pathogenesis of CH-Und ETT-ETT we derive from the earliest, undifferentiated stage of orthological trophoblast. The origin from the differentiated intermediate trophoblast chorion leeve we considerei improbable. 10) There are continuous transitions from CH-Und-ETT and PSTT to CH-NST, representing an analogy to grading in other malignant epithelial tumors.

The Japanese trophoblastic disease classification

OBJECTIVE

To evaluate the clinical usefulness of the "diagnostic score"for the detection of choriocarcinoma in persistent gestational trophoblastic disease without histologic findings.

STUDY DESIGN

We reviewed the clinical records of and histologic reports on all 809 patients with persistent gestational trophoblastic disease treated with surgery and chemotherapy in Japan. There were 347 cases of choriocarcinoma and 462 cases of invasive mole with histologic confirmation. We retrospectively applied the diagnostic score to all the patients.

RESULTS

The sensitivity of the score for choriocarcinoma (the true positive rate of the score for histologic diagnosis of choriocarcinoma) was 91.4%. The specificity of the score (the true positive rate of the score for the histologic diagnosis of invasive mole) was 94.1%. The accuracy of the score was 92.8%.

CONCLUSION

The diagnostic score is a unique scoring system for differentiating choriocarcinoma clinically from persistent gestational trophoblastic disease without histologic findings and for selecting the most appropriate chemotherapy. Proper management in the early stages strongly influences the outcome of these diseases. The scoring system should be very useful for comparing the nearly true incidence and treatment results with choriocarcinoma between nations.

A patient with primary gastric choriocarcinoma who received a correct preoperative diagnosis and achieved prolonged survival

Primary choriocarcinoma of the stomach is an extremely rare and highly malignant tumor. A 68-year-old Japanese man was admitted to our department with symptoms of epigastric pain, abdominal fullness, and dizziness. Primary gastric choriocarcinoma with regional lymph node metastases was diagnosed preoperatively by the detection of elevated serum levels of a tumor marker, radiography, and immunohistochemical staining of biopsy specimens. The patient underwent total gastrectomy and jejunal reconstruction (Roux-en-Y method), followed by chemotherapy. Histological examination of the resected stomach revealed typical choriocarcinoma accompanied by common adenocarcinomatous elements. After postoperative chemotherapy the patient survived for 4 years and 6 months, and died with no evidence of recurrence of carcinoma. This is the first known patient with primary gastric choriocarcinoma to have survived for such a long period without recurrent elevation of the serum level of human chorionic gonadotropin (HCG), which was a useful marker when reevaluating the patient.

Sad fetus syndrome--gestational trophoblastic disease concurrent with a living fetus or fetuses

The term gestational trophoblastic disease is used to indicate a group of both benign and malignant trophoblast, including molar degeneration of villi, hydatid mole, invasive mole and choriocarcinoma. This study shows a new classification of trophoblastic disease existing with a living fetus or fetuses. Benign hydatid mole is the initial stage of the disease continuum, whereas highly malignant choriocarcinoma is the final stage of this spectrum.

The nature of gestational choriocarcinoma latent over two years

In cases of gestational choriocarcinoma, the period from antecedent pregnancy to the onset of the disease (latent period) is watched as a risk factor. When this period was calculated in about 106 cases collected, a period of more than 2 years was found in 8 cases. Therefore, concerning these 8 cases, investigation was made into the chief complaint, the kind of antecedent pregnancy, clinical stage classification, hCG value on diagnosis, histological classification and prognosis. As to the kind of antecedent pregnancy, 7 cases out of 8 were hydatidiform moles (87.5%). However, in 98 cases with a latent period within 2 years, the number of cases of mole antecedent was 54 (55.1%). With the lengthening of the latent period the incidence of antecedent hydatidiform mole tended to increase. Moreover, in the histological classification, particularly in our CPV classification, 7 cases were seen to be P type or V type. In the long-term cases over 2 years a high degree of histological malignancy was observed compared with those of latent periods of less than 2 years.

Histopathologic classification of uterine choriocarcinoma

Histopathologic features of uterine choriocarcinoma were studied to establish new criteria for grading malignancy of the disease. Thirteen items of histopathologic findings concerning the degree of differentiation and the forms of masses of trophoblasts (Trs), the manner of Tr invasion, and host response of surrounding tissues were studied with relationship to prognosis in 70 patients with uterine lesions (alive, 49; dead, 21). Chi-square test results were examined for each item in relation to prognosis of the patients. Four items were thought to have significance and were selected as criteria: (1) island formation; (2) massive proliferation of intermediate-type Trs; (3) rectangular infiltration of Trs to surrounding muscle fibers; and (4) atypia of Trs at the end-point of tumor invasion. A discriminant analysis was carried out (under the standardization of tumor extension and the historical staging of treatment). From the results obtained in discriminant analysis, scores were given to the four items that existed in the specimen. New criteria for grading malignancy are proposed based on scoring these four items. The algebraic sum of the scores had a possible range of +4 to -16. Patients with scores of -9 and above had a low-grade malignancy with a mortality rate of 7%. Patients with scores of -10 and lower had a mortality of 69% and were classified as having tumors of high-grade malignancy.

Placental-site chorioma. The neoplasm of the implantation-site trophoblast

The unusual lesion of gestational trophoblast, variously termed "placental site tumor" and "placental site trophoblastic tumor," may complicate or follow seemingly normal pregnancy, abortion or hydatidiform mole. Posing indeterminate risks of malignant behavior, those lesions must be differentiated from the banal processes of implantation-site reaction, on the one hand, and from choriocarcinoma and other poorly differentiated uterine neoplasms, on the other. A history of antecedent pregnancy, serum assay of chorionic gonadotropin and human placental lactogen, and immunohistochemical studies of tumor tissue lead to a correct diagnosis. Assessment of the degree of malignancy may be problematic in individual cases, and treatment is not always successful. With an origin in the chorionic epithelium at the implantation site, this condition may be termed "placental-site chorioma." Refined diagnostic criteria may then provide a basis for designating some lesions benign chorioma and others malignant--i.e., placental-site choriocarcinoma.

Further observations on the sonographic spectrum of gestational trophoblastic disease

Sonograms of 27 patients with gestational trophoblastic disease were evaluated and categorized to newer concepts regarding the pathology and pathogenesis of this disorder. The patients were assigned to the following subgroups: 1) classical or complete mole; 2) partial or incomplete mole; 3) coexistent mole and fetus; 4) hydropic degeneration of the placenta; 5) locally invasive mole; and 6) metastatic trophoblastic disease, including choriocarcinoma. The utility of this categorization and of ultrasound in the diagnosis and subsequent management of these patients is presented.

Testicular germ cell tumours: should current classification be revised?

The potential inadequacies of current classifications of germ cell tumours are examined in the light of recent evidence high-lighting their high incidence of HCG and AFP production together with the responsible cell types.

[Germinal testicular tumors]

Characteristic for the germinal cell tumors of the testis is their great variety. Collins and Pugh gave a classification of testis tumors under consideration of the genesis of the tumor and the clinical progressing. The staging should be done according to the TNM-system which is based on the UICC recommendations of 1973. If a tumor is suspected an exploration of the testis must be performed. After definitive histological diagnosis via immediate section for microscopic examination during surgery an enlarged orchiectomy and local lymph node dissection has to be performed. In cases of seminoma a 5-year-survival-rate of 90 to 97 per cent can be achieved by radiation of two fields (4 fields in case metastases are suspected). Because of the radio resistance of the teratoid tumors a retroperitoneal lymph node dissection has to follow the enlarged orchiectomy. With a subtile operating technique all the lymph nodes between diaphragm and aortic bifuraction can be removed in case of operability. Postoperative radiation therapy is only recommended in case of excessive lymph node metastases. By an adjuvant chemotherapy following retroperitoneal lymph node dissection a 5-year-survival-rate of more than 80 per cent can be obtained in cases of teratoid tumors.

Gestational trophoblastic neoplasms

A review of the classification, biological behavior, clinical diagnosis, and treatment of gestational trophoblastic neoplasms is presented. The events which followed the utilization of chemotherapy as a successful means of therapy are included. Especially important has been the recent recognition that high risk patients, i.e., patients with HCG titers greater than 100,000 IU/24 hr, duration of symptoms greater than four months, and metastasis to the brain and/or liver, with metastatic trophoblastic disease can be managed successfully if treated initially with combination chemotherapy and adjuvant measures including radiation and infusional therapy. Detectable levels of human chorionic gonadotropin are necessary for diagnosis and management of patients with this disease. The lack of sensitivity of commercially available pregnancy tests and the recent ability to determine HCG by means of an antigenically different beta-subunit are discussed.