Choriocarcinoma and Placental Site Trophoblastic Tumor

The expression and localization of neutral endopeptidase 24.11/CD10 in human gestational trophoblastic diseases

Neutral endopeptidase 24.11 (NEP)/CD10 is a cell-surface peptidase that hydrolyzes various bioactive peptides. NEP is distributed in both normal and neoplastic cells and plays a functional role by modulating cellular responses to peptide substrates. Recently, NEP has been shown to be expressed in normal placental trophoblasts, suggesting its physiological role during pregnancy. In the present study, we investigated the expression of NEP in hyperplastic and anaplastic trophoblasts in gestational trophoblastic diseases (GTDs). Flow cytometric analysis demonstrated that NEP was expressed in all choriocarcinoma cell lines examined. The NEP enzyme activity in these cell lines correlated with cell-surface protein levels and was abolished by the NEP inhibitor phosphoramidon. On immunoblot analysis, NEP protein was detected in both hydatidiform mole and choriocarcinoma tissues as a double band of 95 and 100 kDa similar to that of the normal placental tissues. Immunohistochemical analysis revealed that NEP was present on syncytiotrophoblasts, while no or very faint NEP immunoreactivity was observed on cytotrophoblasts in the normal placenta. Similarly, NEP in hydatidiform mole and invasive mole was localized on the membrane of syncytiotrophoblasts, but not on hyperplastic cytotrophoblasts. In contrast, in choriocarcinoma, NEP was highly expressed not only on syncytiotrophoblastic cells but also on invading anaplastic cytotrophoblasts. In addition, NEP was also expressed on intermediate trophoblasts in placental site trophoblastic tumors. In summary, this is the first study demonstrating the expression of NEP/CD10 in GTDs. The differential localization of NEP among various trophoblastic tumors suggests that NEP may play a functional role in the regulation of trophoblast transformation and human chorionic gonadotropin secretion.

Gestational trophoblastic tumors

Gestational trophoblastic tumor is a term applied to invasive mole, choriocarcinoma, and placental-site trophoblastic tumor. The overall cure rate in the treatment of these gestational trophoblastic tumors now exceeds 90%. This high success rate is the result of (1) inherent sensitivity of trophoblastic tumors to chemotherapy, (2) ability to monitor therapy effectively with the use of human chorionic gonadotropin as a tumor marker, and (3) identification of prognostic factors which allows categorization of patients into high- and low-risk groups for selection of treatment. Virtually all patients with nonmetastatic and low-risk metastatic disease can be cured using single-agent methotrexate or Actinomycin-D chemotherapy. Intensive therapy with combination chemotherapy including etoposide, high-dose methotrexate and Actinomycin D and, where indicated, adjuvant radiotherapy and surgery has resulted in cure rates of 80-90% in patients with high-risk metastatic disease. The factors which are most important in determining response to treatment are: (1) clinicopathologic diagnosis of choriocarcinoma, (2) metastases to sites other than the lung or vagina, (3) number of metastases, (4) previous failed chemotherapy, and (5) WHO score greater than or equal to 8.

The human placental bed: histology, immunohistochemistry and pathology

There has been much interest recently on local intra-uterine materno-fetal interactions particularly in the placental bed where cellular relationships between mother and fetus are at their most intimate. While few histopathologists are expected to interpret formal placental bed biopsy specimens, confrontation with tissue from this site is common following abortion, post-partum haemorrhage or molar gestation. This review gives an account of recent advances in our knowledge of the histology, immunohistochemistry and pathology of the placental bed. It focuses particularly on extravillous trophoblast populations and their relationship to maternal cells and emphasizes the importance of vascular changes.