[Incidental chorangiocarcinoma : Case report, immunohistochemistry and theories of possible histogenesis].

We describe the third case world-wide of a chorangiocarcinoma, a tumour with an abnormal trophoblast proliferation in combination with a hypervascular chorangiosis of the villous stroma. The lesion was an incidential finding by a healthy 31-year-old woman, gravida 1, para 1 when the pregnancy was terminated at 34 weeks gestation because of fetal distress and intrauterine growth restriction. Hormonal levels were within the normal range. Mother and infant had an uneventful postpartum course. Immunohistochemical studies of the abnormal trophoblasts demonstrated strong immunoreactivity for HCG and in 80% for Ki 67. The semiquantitative expression of angiogenic growth factors (VEGF, bFGF, Ang-1 und Ang-2, PDGF) in the tumour trophoblasts was similar to that seen in the normal villi. The pathogenesis of this tumour with a villous vascular response is curious and unclear. Possibilities include the occurrence of a variant of a chorion carcinoma, the occurrence of a new tumour entity or of two separate lesions, a chorangioma and incidential chorion carcinoma, present together as a "collision" tumour. Another possibility is a composition tumour or a reactive lesion of trophoblasts and the villous vascular tree.