Immunohistochemistry in the diagnosis of the gestational trophoblastic disease.

The gestational trophoblastic disease summarizes all types of hydatidiform moles, placental site trophoblastic tumor and choriocarcinoma. It is of clinical relevance to distinguish between complete hydatidiform mole and partial hydatidiform mole to predict prognosis of recurrency of molar pregnancy and the risk of the development of malign and metastatic gestational trophoblastic disease. Differential diagnosis of choriocarcinoma versus placental site trophoblastic tumor, carcinoma or sarcoma with low differentiation can cause problems in borderline-cases. The present study investigates the value of immunohistochemistry in the diagnosis of gestational trophoblastic disease. Nine cases of patients with complete hydatidiform mole, 20 cases of partial hydatidiform mole and seven cases of choriocarcinoma were analyzed for the immunohistochemical reaction with antibodies against human choriogonadotropin (hCG), human placental lactogen (hPL). placental alkaline phosphatase (PLAP), cytokeratine and vimentin. Complete hydatidiform mole shows strong expression of hCG and weak expression of PLAP. Weak hCG and strong PLAP expression is found in partial hydatidiform mole. Choriocarcinoma presents strong expression of hCG and weak expression of hPL and PLAP. All tissues show positive reaction with anticytokeratine and negative reaction with anti-vimentin. Our study proves immunohistochemistry as useful tool for differential diagnosis in borderline cases of gestational trophoblastic disease.