[Malignancies in relatives of retinoblastoma patients (author's transl)].

In 14 out of 25 patients with retinoblastoma there was a family history of malignancies. Most of the malignant tumours had been carcinomas. In 2 families relatives died because of leukaemia; in these cases the tumour was a so-called diffuse retinoblastoma occurring in elder children. A third family with a retinoblastoma in one child and leukaemia in another is mentioned. This unusual coincidence of two tumourous conditions of which one might be of viral origin led to detailed electron microscopic examination of the retinoblastoma in one case; but there were no signs of reduplicating viruses.