The histopathology of trophoblastic tumours

Two important advances in the last 40 years have had a profound effect on the prognosis of patients with trophoblastic tumours. In the first place the application of gonadotrophin assay, initially by biological methods and then by the more accurate radioimmunological methods, to the diagnostic problems of patients with trophoblastic disease has made their management considerably easier. Secondly the discovery that choriocarcinoma, previously among the most rapidly fatal of all tumours, was amenable to treatment with cytotoxic agents has revolutionized therapy, with a reduction in the crude death rate from over 85% to less than 20 %. It has been increasingly suggested that with the growing use of diagnostic aids such as gonadotrophin assay, arteriography and radiography, the usefulness of histological examination has diminished. In some cases this is true; for instance, in the follow up of a patient with hydatidiform mole, when, in the face of a persistently raised gonadotrophin excretion, it may be inadvisable to delay treatment by waiting for histological confirmation of the diagnosis. Nevertheless, curettage is still widely used as the initial diagnostic procedure in the investigation of uterine bleeding, and it is in this situation that the histopathologist will be confronted by the problem of the difficult trophoblastic curetting. Furthermore, the final diagnosis of malignancy, with trophoblastic as with any other tumour, should still ideally be made on histological grounds. Failure to recognize this has resulted in exaggerated claims for cure rates, by including in a malignant category, without histological proof, cases which have pursued an apparently benign course. A major drawback in investigating these tumours fully has been the difficulty in collecting together enough cases for a detailed study. For instance, in Britain most clinicians and pathologists are unlikely to see more than two or three cases of choriocarcinoma in their professional lives. The author was particularly fortunate in being associated with Dr Kenneth Bagshawe's Unit at Charing Cross Hospital, London, for a number of years, with access to the pathological material and case records of over 200 patients with trophoblastic disease. It is on this material that the current review of the pathological aspects of trophoblastic disease is based.