[Unexpected findings in laparotomy. Clinical and morphological aspects of the malignant hemangiopericytoma (author's transl)].

A case of hemangiopericytoma with a component of fibrosarcoma is reported. The tumour was diagnosed three years prior to the first operation which was done for increasing growth of the tumour. Three years after the first operation and radiotherapy a local recurrence was removed. Histology of the tumour showed a pure fibrosarcoma. The patient remains well for more than one year after the second operation. Because of the prolonged course without general spread is questionable that retroperitoneal tumours show the same biological propensities as other fibrosarcomas.