Immunocytochemical localization of chorionic gonadotropin, placental lactogen, and placental alkaline phosphatase in the diagnosis of complete and partial hydatidiform moles.

Complete hydatidiform moles (CHMs) and partial hydatidiform moles (PHMs) represent different clinicopathologic entities with characteristic morphologic and cytogenetic findings. In the absence of cytogenetic data, the histologic distinction between these lesions and abortuses showing hydropic swelling (AHS) may be difficult. An immunocytochemical study analyzing the distribution of human chorionic gonadotropin (hCG), human placental lactogen (hPL), and placental alkaline phosphatase (PlAP) in CHMs, PHMs, and AHS was undertaken to determine whether the expression of these trophoblastic proteins might assist in the differential diagnosis. A total of 24 CHMs, 22 PHMs, and 13 AHS were selected on the basis of established morphologic criteria. Thirty-four specimens of abortuses without hydropic swelling and normal placentas, ranging from 6 to 24 weeks gestational age, were similarly analyzed. The immunocytochemical localization of the three trophoblastic proteins, predominantly in syncytiotrophoblast (ST), was scored using a semiquantitative scoring system. In CHMs hCG is widely distributed and PlAP is patchily distributed in ST regardless of the gestational age, whereas hPL tends to increase with increasing gestational age. In contrast, in PHMs hPL is more widely distributed in ST compared with CHMs regardless of gestational age, while PlAP increases with increasing gestational age; in PHMs the distribution of hCG is markedly less than in CHMs except early in the first trimester when the staining patterns are similar. The different patterns of distribution of hCG, hPL, and PlAP may reflect differences in the pathobiology of trophoblast in CHMs and PHMs and appear to be useful in the differential diagnosis of these conditions.

Intermediate trophoblast: a distinctive form of trophoblast with specific morphological, biochemical and functional features.

Morphological and immunohistochemical analysis of placental tissue from 12 days to term using antibodies directed against the unique carboxyl terminal peptide of human chorionic gonadotrophin beta subunit, human placental lactogen (hPL) and pregnancy-specific beta I-glycoprotein reveals that an intermediate form of trophoblast with distinctive features exists. This cell has a diverse morphological expression and is located overlying chorionic villi, in the trophoblastic columns, basal plate and the trophoblastic shell. Although all three placental proteins are localized in this cell the predominant hormone is hPL, which can serve as an immunocytochemical marker. One of the primary functions of this cell is in implantation and in the establishment of the uteroplacental circulation since it extensively invades the spiral arteries at the placental site. It is proposed that this distinctive form of trophoblast be termed 'intermediate trophoblast'.

Immunocytochemical localization of placental lactogen and chorionic gonadotropin in the normal placenta and trophoblastic tumors, with emphasis on intermediate trophoblast and the placental site trophoblastic tumor.

This report presents preliminary observations on the immunocytochemical localization of human chorionic gonadotropin (hCG) and human placental lactogen (hPL) in placental site trophoblastic tumors, hydatidiform moles, and choriocarcinomas and compares the findings with those of a similar immunocytochemical analysis of the placenta at various stages of development. In addition to cytotrophoblast (CT) and syncytiotrophoblast (ST), a third form of trophoblast designated "intermediate trophoblast" (IT) is present during normal pregnancy and in trophoblastic disease. Intermediate trophoblastic cells are mononucleate, larger than CT, and contain more abundant eosinophilic cytoplasm, resulting in a partial resemblance to ST. Intermediate trophoblast has distinctive immunocytochemical features that distinguish it from CT and ST. The localization of hPL and hCG in both IT and ST varies with the age of the placenta, with the type of trophoblastic neoplasm, and from one specimen to another within each category of tumor. Syncytiotrophoblast may contain both hormones in large amounts, whereas IT contains hPL predominantly and hCG focally. Cytotrophoblast is devoid of hCG and hPL except in choriocarcinoma, which may show focal weak staining for hCG. Immunocytochemical identification of hCG and hPL has proved helpful in clarifying the histogenesis of trophoblastic neoplasms and may also be of value in establishing their diagnosis and in determining their prognosis.