Placenta-associated plasma protein-A (PAPP-A, SP4) in trophoblastic tumours

The immunoperoxidase technique was used to study the occurrence of placenta-associated plasma protein A (PAPP-A, SP4) in formalin-fixed paraffin-embedded tissue specimens from 15 hydatidiform moles, 6 invasive moles and 7 choriocarcinomas. PAPP-A was found in the syncytiotrophoblast of all hydatidiform moles, in 5 of the 6 invasive moles and in 6 of the 7 choriocarcinomata. No clinical difference was observed between PAPP-A positive and negative cases of invasive disease.